Implement auto mode for automatic flight

Use arm/disarm gestures
Add arm/disarm commands
Add ratesExtra variable for 
Rename interpretRC to interpretControls
Rename controlRate to controlRates
Remove USER mode
Add invalidate methods for vector and quaternion
Add valid/invalid method for vector and quaternion
Add valid/invalid function
Print armed in rc command
Pass auto mode to heartbeat
Use actuator_control_target for motors

.github/workflows/build.yml

@@ -23,10 +23,8 @@ jobs:
       with:
         name: firmware-binary
         path: flix/build
-    - name: Build firmware for ESP32-C3
+    - name: Build firmware without Wi-Fi
-      run: make BOARD=esp32:esp32:esp32c3
+      run: sed -i 's/^#define WIFI_ENABLED 1$/#define WIFI_ENABLED 0/' flix/flix.ino && make
-    - name: Build firmware for ESP32-S3
-      run: make BOARD=esp32:esp32:esp32s3
     - name: Check c_cpp_properties.json
       run: tools/check_c_cpp_properties.py
 
@@ -55,25 +53,15 @@ jobs:
       run: python3 tools/check_c_cpp_properties.py
 
   build_simulator:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
-    container:
-      image: ubuntu:20.04
     steps:
-    - name: Install dependencies
-      run: |
-        apt-get update
-        DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget build-essential cmake g++ pkg-config gnupg2 lsb-release sudo
     - name: Install Arduino CLI
       uses: arduino/setup-arduino-cli@v1.1.1
     - uses: actions/checkout@v4
     - name: Install Gazebo
-      run: |
+      run: curl -sSL http://get.gazebosim.org | sh
-        sudo sh -c 'echo "deb http://packages.osrfoundation.org/gazebo/ubuntu-stable `lsb_release -cs` main" > /etc/apt/sources.list.d/gazebo-stable.list'
-        wget https://packages.osrfoundation.org/gazebo.key -O - | sudo apt-key add -
-        sudo apt-get update
-        sudo apt-get install -y gazebo11 libgazebo11-dev
     - name: Install SDL2
-      run: sudo apt-get install -y libsdl2-dev
+      run: sudo apt-get install libsdl2-dev
     - name: Build simulator
       run: make build_simulator
     - uses: actions/upload-artifact@v4

.gitignore

@@ -4,10 +4,9 @@ build/
 tools/log/
 tools/dist/
 *.egg-info/
-.core
+.dependencies
-.libs
 .vscode/*
-!.vscode/settings.default.json
+!.vscode/settings.json
 !.vscode/c_cpp_properties.json
 !.vscode/tasks.json
 !.vscode/launch.json

.markdownlint.json

@@ -7,8 +7,6 @@
 	"MD024": false,
 	"MD033": false,
 	"MD034": false,
-	"MD040": false,
-	"MD059": false,
 	"MD044": {
 		"html_elements": false,
 		"code_blocks": false,
@@ -66,6 +64,5 @@
 			"PX4"
 		]
 	},
-	"MD045": false,
+	"MD045": false
-	"MD060": false
 }

.vscode/c_cpp_properties.json

@@ -5,19 +5,18 @@
 			"includePath": [
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
-				"${workspaceFolder}/tools/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
-				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Arduino/libraries/**",
-				"/usr/include/gazebo-11/",
+				"/usr/include/**"
-				"/usr/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -30,10 +29,9 @@
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
-				"${workspaceFolder}/flix/parameters.ino",
+				"${workspaceFolder}/flix/parameters.ino"
-				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -53,18 +51,19 @@
 			"name": "Mac",
 			"includePath": [
 				"${workspaceFolder}/flix",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
+				// "${workspaceFolder}/gazebo",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/include/**",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**",
-				"/opt/homebrew/include/gazebo-11/",
+				"/opt/homebrew/include/**"
-				"/opt/homebrew/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/flix.ino",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
@@ -77,10 +76,9 @@
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
-				"${workspaceFolder}/flix/parameters.ino",
+				"${workspaceFolder}/flix/parameters.ino"
-				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -102,17 +100,17 @@
 			"includePath": [
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
-				"${workspaceFolder}/tools/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -125,10 +123,9 @@
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
-				"${workspaceFolder}/flix/parameters.ino",
+				"${workspaceFolder}/flix/parameters.ino"
-				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++.exe",
+			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++.exe",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [

.vscode/extensions.json

@@ -1,7 +1,6 @@
 {
 	// See https://go.microsoft.com/fwlink/?LinkId=827846 to learn about workspace recommendations.
 	"recommendations": [
-		"dangmai.workspace-default-settings",
 		"ms-vscode.cpptools",
 		"ms-vscode.cmake-tools",
 		"ms-python.python"

.vscode/settings.json

@@ -1,6 +1,5 @@
 {
 	"C_Cpp.intelliSenseEngineFallback": "enabled",
-	"C_Cpp.errorSquiggles": "disabled",
 	"files.associations": {
 		"*.sdf": "xml",
 		"*.ino": "cpp",

Makefile

@@ -1,40 +1,29 @@
-BOARD = esp32:esp32:d1_mini32:DebugLevel=error
+BOARD = esp32:esp32:d1_mini32
-PORT := $(strip $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-* /dev/cu.usbmodem*))
+PORT := $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-*)
+PORT := $(strip $(PORT))
 
-export ARDUINO_NETWORK_CONNECTION_TIMEOUT := 1h
+build: .dependencies
-
-build: .core .libs
 	arduino-cli compile --fqbn $(BOARD) flix
 
 upload: build
 	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" flix
 
-erase:
-	arduino-cli burn-bootloader --fqbn $(BOARD) -p "$(PORT)" -P esptool
-
 monitor:
 	arduino-cli monitor -p "$(PORT)" -c baudrate=115200
 
-core .core:
+dependencies .dependencies:
-	arduino-cli core update-index --additional-urls https://espressif.github.io/arduino-esp32/package_esp32_index.json
+	arduino-cli core update-index --config-file arduino-cli.yaml
-	arduino-cli core install esp32:esp32@3.3.10 --additional-urls https://espressif.github.io/arduino-esp32/package_esp32_index.json
+	arduino-cli core install esp32:esp32@3.2.0 --config-file arduino-cli.yaml
-	touch .core
-
-libs .libs:
 	arduino-cli lib update-index
 	arduino-cli lib install "FlixPeriph"
-	arduino-cli lib install "MAVLink"@2.0.25
+	arduino-cli lib install "MAVLink"@2.0.16
-	touch .libs
+	touch .dependencies
-
-upload_proxy: .core .libs
-	arduino-cli compile --fqbn $(BOARD) tools/espnow-proxy
-	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" tools/espnow-proxy
 
 gazebo/build cmake: gazebo/CMakeLists.txt
 	mkdir -p gazebo/build
 	cd gazebo/build && cmake ..
 
-build_simulator: .libs gazebo/build
+build_simulator: .dependencies gazebo/build
 	make -C gazebo/build
 
 simulator: build_simulator
@@ -43,12 +32,12 @@ simulator: build_simulator
 	gazebo --verbose ${CURDIR}/gazebo/flix.world
 
 log:
-	tools/log.py
+	PORT=$(PORT) tools/grab_log.py
 
 plot:
 	plotjuggler -d $(shell ls -t tools/log/*.csv | head -n1)
 
 clean:
-	rm -rf gazebo/build flix/build flix/cache .core .libs
+	rm -rf gazebo/build flix/build flix/cache .dependencies
 
-.PHONY: build upload monitor core libs cmake build_simulator simulator log clean
+.PHONY: build upload monitor dependencies cmake build_simulator simulator log clean

README.md

@@ -1,9 +1,6 @@
-<!-- markdownlint-disable MD041 -->
+# Flix
 
-<p align="center">
+**Flix** (*flight + X*) — making an open source ESP32-based quadcopter from scratch.
-  <img src="docs/img/flix.svg" width=180 alt="Flix logo"><br>
-  <b>Flix</b> (<i>flight + X</i>) — open source ESP32-based quadcopter made from scratch.
-</p>
 
 <table>
   <tr>
@@ -20,14 +17,16 @@
 
 * Dedicated for education and research.
 * Made from general-purpose components.
-* Simple and clean source code in Arduino (<2k lines firmware).
+* Simple and clean source code in Arduino.
-* Communication using MAVLink protocol over Wi-Fi or ESP-NOW.
+* Control using remote control or smartphone.
-* Control with USB gamepad, remote control or smartphone.
-* Wireless command line interface and analyzing.
 * Precise simulation with Gazebo.
-* Python library for scripting and automatic flights.
+* Wi-Fi and MAVLink support.
+* Wireless command line interface and analyzing.
+* Python library.
 * Textbook on flight control theory and practice ([in development](https://quadcopter.dev)).
-* *Position control (planned)*.
+* *Position control (using external camera) and autonomous flights¹*.
+
+*¹ — planned.*
 
 ## It actually flies
 
@@ -39,69 +38,55 @@ Version 0 demo video: https://youtu.be/8GzzIQ3C6DQ.
 
 <a href="https://youtu.be/8GzzIQ3C6DQ"><img width=500 src="https://i3.ytimg.com/vi/8GzzIQ3C6DQ/maxresdefault.jpg"></a>
 
-Usage in education (RoboCamp): https://youtu.be/Wd3yaorjTx0.
+See the [user builds gallery](docs/user.md).
-
-<a href="https://youtu.be/Wd3yaorjTx0"><img width=500 src="https://i3.ytimg.com/vi/Wd3yaorjTx0/sddefault.jpg"></a>
-
-See the [user builds gallery](docs/user.md):
 
 <a href="docs/user.md"><img src="docs/img/user/user.jpg" width=500></a>
 
-### PCB
-
-The official PCB *(Flix2)* is in development now. Follow the [project's channel](https://t.me/opensourcequadcopter) to track the progress.
-
-Outdoor flights demo video of the current prototype:
-
-<a href="https://youtu.be/KXlNmvUTi4g"><img width=300 src="https://i3.ytimg.com/vi/KXlNmvUTi4g/maxresdefault.jpg"></a>
-
 ## Simulation
 
 The simulator is implemented using Gazebo and runs the original Arduino code:
 
 <img src="docs/img/simulator1.png" width=500 alt="Flix simulator">
 
-## Documentation articles
+## Articles
 
-1. [Assembly instructions](docs/assembly.md).
+* [Assembly instructions](docs/assembly.md).
-2. [Usage: build, setup and flight](docs/usage.md).
+* [Building and running the code](docs/build.md).
-3. [Simulation](gazebo/README.md).
-4. [Python library](tools/pyflix/README.md).
-
-Additional articles:
-
-* [User builds gallery](docs/user.md).
-* [Firmware architectural overview](docs/firmware.md).
 * [Troubleshooting](docs/troubleshooting.md).
+* [Firmware architecture overview](docs/firmware.md).
+* [Python library tutorial](tools/pyflix/README.md).
 * [Log analysis](docs/log.md).
+* [User builds gallery](docs/user.md).
 
 ## Components
 
 |Type|Part|Image|Quantity|
 |-|-|:-:|:-:|
-|Microcontroller board|ESP32 Mini.<br>ESP32-S3/ESP32-C3 boards are also supported.|<img src="docs/img/esp32.jpg" width=100>|1|
+|Microcontroller board|ESP32 Mini|<img src="docs/img/esp32.jpg" width=100>|1|
-|IMU (and barometer¹) board|GY‑91, MPU-9265 (or other MPU‑9250/MPU‑6500 board)<br>ICM20948V2 (ICM‑20948)<br>GY-521 (MPU-6050)|<img src="docs/img/gy-91.jpg" width=90 align=center><br><img src="docs/img/icm-20948.jpg" width=100><br><img src="docs/img/gy-521.jpg" width=100>|1|
+|IMU (and barometer²) board|GY‑91, MPU-9265 (or other MPU‑9250/MPU‑6500 board)<br>ICM‑20948³<br>GY-521 (MPU-6050)³⁻¹|<img src="docs/img/gy-91.jpg" width=90 align=center><br><img src="docs/img/icm-20948.jpg" width=100><br><img src="docs/img/gy-521.jpg" width=100>|1|
-|*Boost converter (optional, for more stable power supply)*|*5V output*|<img src="docs/img/buck-boost.jpg" width=100>|1|
+|<span style="background:yellow">(Recommended) Buck-boost converter</span>|To be determined, output 5V or 3.3V, see [user-contributed schematics](https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612179508274&cot=14)|<img src="docs/img/buck-boost.jpg" width=100>|1|
-|Motor|8520 3.7V brushed motor.<br>Motor with exact 3.7V voltage is needed, not ranged working voltage (3.7V — 6V).<br>Make sure the motor shaft diameter and propeller hole diameter match!|<img src="docs/img/motor.jpeg" width=100>|4|
+|Motor|8520 3.7V brushed motor (shaft 0.8mm).<br>Motor with exact 3.7V voltage is needed, not ranged working voltage (3.7V — 6V).|<img src="docs/img/motor.jpeg" width=100>|4|
-|Propeller|55 mm or 65 mm|<img src="docs/img/prop.jpg" width=100>|4|
+|Propeller|Hubsan 55 mm|<img src="docs/img/prop.jpg" width=100>|4|
 |MOSFET (transistor)|100N03A or [analog](https://t.me/opensourcequadcopter/33)|<img src="docs/img/100n03a.jpg" width=100>|4|
-|Pull-down resistor<br>Voltage measurement resistor|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|6|
+|Pull-down resistor|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|4|
-|3.7V Li-Po battery|LW 952540 (or any compatible by the size).<br>Make sure the battery has enough discharge rate — 25C or more!|<img src="docs/img/battery.jpg" width=100>|1|
+|3.7V Li-Po battery|LW 952540 (or any compatible by the size)|<img src="docs/img/battery.jpg" width=100>|1|
 |Battery connector cable|MX2.0 2P female|<img src="docs/img/mx.png" width=100>|1|
 |Li-Po Battery charger|Any|<img src="docs/img/charger.jpg" width=100>|1|
 |Screws for IMU board mounting|M3x5|<img src="docs/img/screw-m3.jpg" width=100>|2|
 |Screws for frame assembly|M1.4x5|<img src="docs/img/screw-m1.4.jpg" height=30 align=center>|4|
-|Frame main part|3D printed²: [`stl`](docs/assets/flix-frame-1.1.stl) [`step`](docs/assets/flix-frame-1.1.step)<br>Recommended settings: layer 0.2 mm, line 0.4 mm, infill 100%.|<img src="docs/img/frame1.jpg" width=100>|1|
+|Frame main part|3D printed⁴:<br>[`flix-frame-1.1.stl`](docs/assets/flix-frame-1.1.stl) [`flix-frame-1.1.step`](docs/assets/flix-frame-1.1.step)<br>Recommended settings: layer 0.2 mm, line 0.4 mm, infill 100%.|<img src="docs/img/frame1.jpg" width=100>|1|
-|Frame top part|3D printed: [`stl`](docs/assets/esp32-holder.stl) [`step`](docs/assets/esp32-holder.step)|<img src="docs/img/esp32-holder.jpg" width=100>|1|
+|Frame top part|3D printed:<br>[`esp32-holder.stl`](docs/assets/esp32-holder.stl) [`esp32-holder.step`](docs/assets/esp32-holder.step)|<img src="docs/img/esp32-holder.jpg" width=100>|1|
-|Washer for IMU board mounting|3D printed: [`stl`](docs/assets/washer-m3.stl) [`step`](docs/assets/washer-m3.step)|<img src="docs/img/washer-m3.jpg" width=100>|2|
+|Washer for IMU board mounting|3D printed:<br>[`washer-m3.stl`](docs/assets/washer-m3.stl) [`washer-m3.step`](docs/assets/washer-m3.step)|<img src="docs/img/washer-m3.jpg" width=100>|2|
-|Controller (recommended)|CC2500 transmitter, like BetaFPV LiteRadio CC2500 (RC receiver/Wi-Fi).<br>Two-sticks gamepad (Wi-Fi only) — see [recommended gamepads](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/setup_view/joystick.html#supported-joysticks).<br>Other⁵|<img src="docs/img/betafpv.jpg" width=100><img src="docs/img/logitech.jpg" width=80>|1|
+|*RC transmitter (optional)*|*KINGKONG TINY X8 (warning: lacks USB support) or other⁵*|<img src="docs/img/tx.jpg" width=100>|1|
-|*RC receiver (optional)*|*DF500 or other³*|<img src="docs/img/rx.jpg" width=100>|1|
+|*RC receiver (optional)*|*DF500 or other⁵*|<img src="docs/img/rx.jpg" width=100>|1|
 |Wires|28 AWG recommended|<img src="docs/img/wire-28awg.jpg" width=100>||
 |Tape, double-sided tape||||
 
-*¹ — barometer is not used for now.*<br>
+*² — barometer is not used for now.*<br>
-*² — this frame is optimized for GY-91 board, if using other, the board mount holes positions should be modified.*<br>
+*³ — change `MPU9250` to `ICM20948` in `imu.ino` file if using ICM-20948 board.*<br>
-*³ — you also may use any transmitter-receiver pair with SBUS interface.*
+*³⁻¹ — MPU-6050 supports I²C interface only (not recommended). To use it change IMU declaration to `MPU6050 IMU(Wire)`.*<br>
+*⁴ — this frame is optimized for GY-91 board, if using other, the board mount holes positions should be modified.*<br>
+*⁵ — you may use any transmitter-receiver pair with SBUS interface.*
 
 Tools required for assembly:
 
@@ -111,15 +96,13 @@ Tools required for assembly:
 * Screwdrivers.
 * Multimeter.
 
-Feel free to modify the design and or code, and create your own improved versions. Send your results to the [official Telegram chat](https://t.me/opensourcequadcopterchat), or directly to the author ([E-mail](mailto:okalachev@gmail.com), [Telegram](https://t.me/okalachev)).
+Feel free to modify the design and or code, and create your own improved versions of Flix! Send your results to the [official Telegram chat](https://t.me/opensourcequadcopterchat), or directly to the author ([E-mail](mailto:okalachev@gmail.com), [Telegram](https://t.me/okalachev)).
 
 ## Schematics
 
 ### Simplified connection diagram
 
-<img src="docs/img/schematics1.svg" width=700 alt="Flix version 1 schematics">
+<img src="docs/img/schematics1.svg" width=800 alt="Flix version 1 schematics">
-
-*(Dashed elements are optional).*
 
 Motor connection scheme:
 
@@ -127,6 +110,8 @@ Motor connection scheme:
 
 You can see a user-contributed [variant of complete circuit diagram](https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612338222067&cot=14) of the drone.
 
+See [assembly guide](docs/assembly.md) for instructions on assembling the drone.
+
 ### Notes
 
 * Power ESP32 Mini with Li-Po battery using VCC (+) and GND (-) pins.
@@ -144,15 +129,14 @@ You can see a user-contributed [variant of complete circuit diagram](https://mir
 * Solder pull-down resistors to the MOSFETs.
 * Connect the motors to the ESP32 Mini using MOSFETs, by following scheme:
 
-  |Motor|Position|Direction|Prop type|Motor wires|GPIO|
+  |Motor|Position|Direction|Wires|GPIO|
-  |-|-|-|-|-|-|
+  |-|-|-|-|-|
-  |Motor 0|Rear left|Counter-clockwise|B|Black & White|GPIO12 *(TDI)*|
+  |Motor 0|Rear left|Counter-clockwise|Black & White|GPIO12 (*TDI*)|
-  |Motor 1|Rear right|Clockwise|A|Blue & Red|GPIO13 *(TCK)*|
+  |Motor 1|Rear right|Clockwise|Blue & Red|GPIO13 (*TCK*)|
-  |Motor 2|Front right|Counter-clockwise|B|Black & White|GPIO14 *(TMS)*|
+  |Motor 2|Front right|Counter-clockwise|Black & White|GPIO14 (*TMS*)|
-  |Motor 3|Front left|Clockwise|A|Blue & Red|GPIO15 *(TD0)*|
+  |Motor 3|Front left|Clockwise|Blue & Red|GPIO15 (*TD0*)|
 
-  Clockwise motors have blue & red wires and correspond to propeller type A (marked on the propeller).
+  Counter-clockwise motors have black and white wires and clockwise motors have blue and red wires.
-  Counter-clockwise motors have black & white wires correspond to propeller type B.
 
 * Optionally connect the RC receiver to the ESP32's UART2:
 
@@ -160,20 +144,32 @@ You can see a user-contributed [variant of complete circuit diagram](https://mir
   |-|-|
   |GND|GND|
   |VIN|VCC (or 3.3V depending on the receiver)|
-  |Signal (TX)|GPIO4|
+  |Signal (TX)|GPIO4⁶|
 
-* Optionally connect the battery voltage divider for voltage monitoring to any ADC1 pin (e. g. *GPIO32* on ESP32, *GPIO3* on ESP32-S3).
+*⁶ — UART2 RX pin was [changed](https://docs.espressif.com/projects/arduino-esp32/en/latest/migration_guides/2.x_to_3.0.html#id14) to GPIO4 in Arduino ESP32 core 3.0.*
 
-  ESP32 and ESP32-S3 [can measure](https://docs.espressif.com/projects/arduino-esp32/en/latest/api/adc.html#analogsetattenuation) up to 3.1 V and ESP32-S3/ESP32-C3 can measure up to 2.5 V, so choose the voltage divider resistors accordingly.
+### IMU placement
 
-## Resources
+Default IMU orientation in the code is **LFD** (Left-Forward-Down):
 
-* Telegram channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
+<img src="docs/img/gy91-lfd.svg" width=400 alt="GY-91 axes">
-* Official Telegram chat: https://t.me/opensourcequadcopterchat (English / Russian).
+
-* Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.
+In case of using other IMU orientation, modify the `rotateIMU` function in the `imu.ino` file.
+
+See [FlixPeriph documentation](https://github.com/okalachev/flixperiph?tab=readme-ov-file#imu-axes-orientation) to learn axis orientation of other IMU boards.
+
+## Materials
+
+Subscribe to the Telegram channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
+
+Join the official Telegram chat: https://t.me/opensourcequadcopterchat.
+
+Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.
+
+See the information on the obsolete version 0 in the [corresponding article](docs/version0.md).
 
 ## Disclaimer
 
-This is a DIY project, and I hope you find it interesting and useful. However, it's not easy to assemble and set up, and it's provided "as is" without any warranties. There's no guarantee that it will work perfectly, or even work at all.
+This is a fun DIY project, and I hope you find it interesting and useful. However, it's not easy to assemble and set up, and it's provided "as is" without any warranties. There’s no guarantee that it will work perfectly — or even work at all.
 
 ⚠️ The author is not responsible for any damage, injury, or loss resulting from the use of this project. Use at your own risk!

arduino-cli.yaml

@@ -0,0 +1,5 @@
+board_manager:
+  additional_urls:
+    - https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
+network:
+  connection_timeout: 1h

docs/assembly.md

@@ -27,29 +27,3 @@ Soldered components ([schematics variant](https://miro.com/app/board/uXjVN-dTjoo
 <br>Assembled drone:
 
 <img src="img/assembly/7.jpg" width=600>
-
-See an alternative assembly process photos here: https://drive.google.com/drive/folders/1FG5BH9RCzdf1XmJcC70PymiRMXcz6Fx7?usp=sharing.
-
-## Motor directions
-
-> [!WARNING]
-> The drone above is an early build, and it has **inversed** motor directions scheme. The photos only illustrate the assembly process in general.
-
-Use standard motor directions scheme:
-
-<img src="img/motors.svg" width=200>
-
-Motors connection table:
-
-|Motor|Position|Direction|Prop type|Motor wires|GPIO|
-|-|-|-|-|-|-|
-|Motor 0|Rear left|Counter-clockwise|B|Black & White|GPIO12 *(TDI)*|
-|Motor 1|Rear right|Clockwise|A|Blue & Red|GPIO13 *(TCK)*|
-|Motor 2|Front right|Counter-clockwise|B|Black & White|GPIO14 *(TMS)*|
-|Motor 3|Front left|Clockwise|A|Blue & Red|GPIO15 *(TD0)*|
-
-## Motors tightening
-
-Motors should be installed very tightly — any vibration may lead to bad attitude estimation and unstable flight. If motors are loose, use tiny tape pieces to fix them tightly as shown below:
-
-<img src="img/motor-tape.jpg" width=600>

docs/book/firmware.md

@@ -1,10 +1,8 @@
 # Архитектура прошивки
 
-Прошивка Flix это обычный скетч Arduino, реализованный в однопоточном стиле. Код инициализации находится в функции `setup()`, а главный цикл — в функции `loop()`. Скетч состоит из нескольких файлов, каждый из которых отвечает за определенную подсистему.
+<img src="img/dataflow.svg" width=800 alt="Firmware dataflow diagram">
 
-<img src="img/dataflow.svg" width=600 alt="Firmware dataflow diagram">
+Главный цикл работает на частоте 1000 Гц. Передача данных между подсистемами происходит через глобальные переменные:
-
-Главный цикл `loop()` работает на частоте 1000 Гц. Передача данных между подсистемами происходит через глобальные переменные:
 
 * `t` *(float)* — текущее время шага, *с*.
 * `dt` *(float)* — дельта времени между текущим и предыдущим шагами, *с*.
@@ -12,39 +10,23 @@
 * `acc` *(Vector)* — данные с акселерометра, *м/с<sup>2</sup>*.
 * `rates` *(Vector)* — отфильтрованные угловые скорости, *рад/с*.
 * `attitude` *(Quaternion)* — оценка ориентации (положения) дрона.
-* `controlRoll`, `controlPitch`, `controlYaw`, `controlThrottle`, `controlMode` *(float)* — команды управления от пилота, в диапазоне [-1, 1].
+* `controlRoll`, `controlPitch`, ... *(float[])* — команды управления от пилота, в диапазоне [-1, 1].
-* `motors` *(float[4])* — выходные сигналы на моторы, в диапазоне [0, 1].
+* `motors` *(float[])* — выходные сигналы на моторы, в диапазоне [0, 1].
 
 ## Исходные файлы
 
-Исходные файлы прошивки находятся в директории `flix`. Основные файлы:
+Исходные файлы прошивки находятся в директории `flix`. Ключевые файлы:
 
-* [`flix.ino`](https://github.com/okalachev/flix/blob/master/flix/flix.ino) — основной файл Arduino-скетча. Определяет некоторые глобальные переменные и главный цикл.
+* [`flix.ino`](https://github.com/okalachev/flix/blob/canonical/flix/flix.ino) — основной входной файл, скетч Arduino. Включает определение глобальных переменных и главный цикл.
-* [`imu.ino`](https://github.com/okalachev/flix/blob/master/flix/imu.ino) — чтение данных с датчика IMU (гироскоп и акселерометр), калибровка IMU.
+* [`imu.ino`](https://github.com/okalachev/flix/blob/canonical/flix/imu.ino) — чтение данных с датчика IMU (гироскоп и акселерометр), калибровка IMU.
-* [`rc.ino`](https://github.com/okalachev/flix/blob/master/flix/rc.ino) — чтение данных с RC-приемника, калибровка RC.
+* [`rc.ino`](https://github.com/okalachev/flix/blob/canonical/flix/rc.ino) — чтение данных с RC-приемника, калибровка RC.
-* [`estimate.ino`](https://github.com/okalachev/flix/blob/master/flix/estimate.ino) — оценка ориентации дрона, комплементарный фильтр.
+* [`mavlink.ino`](https://github.com/okalachev/flix/blob/canonical/flix/mavlink.ino) — взаимодействие с QGroundControl через MAVLink.
-* [`control.ino`](https://github.com/okalachev/flix/blob/master/flix/control.ino) — подсистема управления, трехмерный двухуровневый каскадный ПИД-регулятор.
+* [`estimate.ino`](https://github.com/okalachev/flix/blob/canonical/flix/estimate.ino) — оценка ориентации дрона, комплементарный фильтр.
-* [`motors.ino`](https://github.com/okalachev/flix/blob/master/flix/motors.ino) — выход PWM на моторы.
+* [`control.ino`](https://github.com/okalachev/flix/blob/canonical/flix/control.ino) — управление ориентацией и угловыми скоростями дрона, трехмерный двухуровневый каскадный PID-регулятор.
-* [`mavlink.ino`](https://github.com/okalachev/flix/blob/master/flix/mavlink.ino) — взаимодействие с QGroundControl или [pyflix](https://github.com/okalachev/flix/tree/master/tools/pyflix) через протокол MAVLink.
+* [`motors.ino`](https://github.com/okalachev/flix/blob/canonical/flix/motors.ino) — управление выходными сигналами на моторы через ШИМ.
 
-Вспомогательные файлы:
+Вспомогательные файлы включают:
 
-* [`vector.h`](https://github.com/okalachev/flix/blob/master/flix/vector.h), [`quaternion.h`](https://github.com/okalachev/flix/blob/master/flix/quaternion.h) — библиотеки векторов и кватернионов.
+* [`vector.h`](https://github.com/okalachev/flix/blob/canonical/flix/vector.h), [`quaternion.h`](https://github.com/okalachev/flix/blob/canonical/flix/quaternion.h) — реализация библиотек векторов и кватернионов проекта.
-* [`pid.h`](https://github.com/okalachev/flix/blob/master/flix/pid.h) — ПИД-регулятор.
+* [`pid.h`](https://github.com/okalachev/flix/blob/canonical/flix/pid.h) — реализация общего ПИД-регулятора.
-* [`lpf.h`](https://github.com/okalachev/flix/blob/master/flix/lpf.h) — фильтр нижних частот.
+* [`lpf.h`](https://github.com/okalachev/flix/blob/canonical/flix/lpf.h) — реализация общего фильтра нижних частот.
-
-### Подсистема управления
-
-Состояние органов управления обрабатывается в функции `interpretControls()` и преобразуется в **команду управления**, которая включает следующее:
-
-* `attitudeTarget` *(Quaternion)* — целевая ориентация дрона.
-* `ratesTarget` *(Vector)* — целевые угловые скорости, *рад/с*.
-* `ratesExtra` *(Vector)* — дополнительные (feed-forward) угловые скорости, для управления рысканием в режиме STAB, *рад/с*.
-* `torqueTarget` *(Vector)* — целевой крутящий момент, диапазон [-1, 1].
-* `thrustTarget` *(float)* — целевая общая тяга, диапазон [0, 1].
-
-Команда управления обрабатывается в функциях `controlAttitude()`, `controlRates()`, `controlTorque()`. Если значение одной из переменных установлено в `NAN`, то соответствующая функция пропускается.
-
-<img src="img/control.svg" width=300 alt="Control subsystem diagram">
-
-Состояние *armed* хранится в переменной `armed`, а текущий режим — в переменной `mode`.

docs/book/geometry.md

@@ -110,7 +110,7 @@ float angle = Vector::angleBetween(a, b); // 1.57 (90 градусов)
 
 #### Скалярное произведение
 
-Скалярное произведение векторов *(dot product)* — это произведение длин двух векторов на косинус угла между ними. В математике оно обозначается знаком `·` или слитным написанием векторов. Интуитивно, результат скалярного произведения показывает, насколько два вектора *сонаправлены*.
+Скалярное произведение векторов (*dot product*) — это произведение длин двух векторов на косинус угла между ними. В математике оно обозначается знаком `·` или слитным написанием векторов. Интуитивно, результат скалярного произведения показывает, насколько два вектора *сонаправлены*.
 
 В Flix используется статический метод `Vector::dot()`:
 
@@ -124,7 +124,7 @@ float dotProduct = Vector::dot(a, b); // 32
 
 #### Векторное произведение
 
-Векторное произведение *(cross product)* позволяет найти вектор, перпендикулярный двум другим векторам. В математике оно обозначается знаком `×`, а в прошивке используется статический метод `Vector::cross()`:
+Векторное произведение (*cross product*) позволяет найти вектор, перпендикулярный двум другим векторам. В математике оно обозначается знаком `×`, а в прошивке используется статический метод `Vector::cross()`:
 
 ```cpp
 Vector a(1, 2, 3);
@@ -144,9 +144,9 @@ Vector crossProduct = Vector::cross(a, b); // -3, 6, -3
 
 В прошивке углы Эйлера сохраняются в обычный объект `Vector` (хоть и, строго говоря, не являются вектором):
 
-* Угол по крену *(roll)* — `vector.x`.
+* Угол по крену (*roll*) — `vector.x`.
-* Угол по тангажу *(pitch)* — `vector.y`.
+* Угол по тангажу (*pitch*) — `vector.y`.
-* Угол по рысканию *(yaw)* — `vector.z`.
+* Угол по рысканию (*yaw*) — `vector.z`.
 
 Особенности углов Эйлера:
 
@@ -162,8 +162,8 @@ Vector crossProduct = Vector::cross(a, b); // -3, 6, -3
 
 Помимо углов Эйлера, любую ориентацию в трехмерном пространстве можно представить в виде вращения вокруг некоторой оси на некоторый угол. В геометрии это доказывается, как **теорема вращения Эйлера**. В таком представлении ориентация задается двумя величинами:
 
-* **Ось вращения** *(axis)* — единичный вектор, определяющий ось вращения.
+* **Ось вращения** (*axis*) — единичный вектор, определяющий ось вращения.
-* **Угол поворота** *(angle* или *θ)* — угол, на который нужно повернуть объект вокруг этой оси.
+* **Угол поворота** (*angle* или *θ*) — угол, на который нужно повернуть объект вокруг этой оси.
 
 В Flix ось вращения задается объектом `Vector`, а угол поворота — числом типа `float` в радианах:
 
@@ -177,7 +177,7 @@ float angle = radians(45);
 
 ### Вектор вращения
 
-Если умножить вектор *axis* на угол поворота *θ*, то получится **вектор вращения** *(rotation vector)*. Этот вектор играет важную роль в алгоритмах управления ориентацией летательного аппарата.
+Если умножить вектор *axis* на угол поворота *θ*, то получится **вектор вращения** (*rotation vector*). Этот вектор играет важную роль в алгоритмах управления ориентацией летательного аппарата.
 
 Вектор вращения обладает замечательным свойством: если угловые скорости объекта (в собственной системе координат) в каждый момент времени совпадают с компонентами этого вектора, то за единичное время объект придет к заданной этим вектором ориентации. Это свойство позволяет использовать вектор вращения для управления ориентацией объекта посредством управления угловыми скоростями.
 
@@ -198,7 +198,7 @@ Vector rotation = radians(45) * Vector(1, 2, 3);
 	<a href="https://github.com/okalachev/flix/blob/master/flix/quaternion.h"><code>quaternion.h</code></a>.<br>
 </div>
 
-Вектор вращения удобен, но еще удобнее использовать **кватернион**. В Flix кватернионы задаются объектами `Quaternion` из библиотеки `quaternion.h`. Кватернион состоит из четырех значений: *w*, *x*, *y*, *z* и рассчитывается из вектора оси вращения *(axis)* и угла поворота *(θ)* по формуле:
+Вектор вращения удобен, но еще удобнее использовать **кватернион**. В Flix кватернионы задаются объектами `Quaternion` из библиотеки `quaternion.h`. Кватернион состоит из четырех значений: *w*, *x*, *y*, *z* и рассчитывается из вектора оси вращения (*axis*) и угла поворота (*θ*) по формуле:
 
 \\[ q = \left( \begin{array}{c} w \\\\ x \\\\ y \\\\ z \end{array} \right) = \left( \begin{array}{c} \cos\left(\frac{\theta}{2}\right) \\\\ axis\_x \cdot \sin\left(\frac{\theta}{2}\right) \\\\ axis\_y \cdot \sin\left(\frac{\theta}{2}\right) \\\\ axis\_z \cdot \sin\left(\frac{\theta}{2}\right) \end{array} \right) \\]
 

docs/book/gyro.md

@@ -87,13 +87,13 @@ Flix поддерживает следующие модели IMU:
 #include <FlixPeriph.h>
 #include <SPI.h>
 
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
 
 void setup() {
 	Serial.begin(115200);
-	bool success = imu.begin();
+	bool success = IMU.begin();
 	if (!success) {
-		Serial.println("Failed to initialize the IMU");
+		Serial.println("Failed to initialize IMU");
 	}
 }
 ```
@@ -108,21 +108,21 @@ void setup() {
 #include <FlixPeriph.h>
 #include <SPI.h>
 
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
 
 void setup() {
 	Serial.begin(115200);
-	bool success = imu.begin();
+	bool success = IMU.begin();
 	if (!success) {
-		Serial.println("Failed to initialize the IMU");
+		Serial.println("Failed to initialize IMU");
 	}
 }
 
 void loop() {
-	imu.waitForData();
+	IMU.waitForData();
 
 	float gx, gy, gz;
-	imu.getGyro(gx, gy, gz);
+	IMU.getGyro(gx, gy, gz);
 
 	Serial.printf("gx:%f gy:%f gz:%f\n", gx, gy, gz);
 	delay(50); // замедление вывода
@@ -135,36 +135,36 @@ void loop() {
 
 ## Конфигурация гироскопа
 
-В коде Flix настройка IMU происходит в функции `configureIMU`. В этой функции настраиваются три основных параметра гироскопа: диапазон измерений, частота сэмплирования и частота LPF-фильтра.
+В коде Flix настройка IMU происходит в функции `configureIMU`. В этой функции настраиваются три основных параметра гироскопа: диапазон измерений, частота сэмплов и частота LPF-фильтра.
 
-### Частота сэмплирования
+### Частота сэмплов
 
-Большинство IMU могут обновлять данные с разной частотой. В полетных контроллерах обычно используется частота обновления от 500 Гц до 8 кГц. Чем выше частота, тем выше точность управления полетом, но и тем больше нагрузка на микроконтроллер.
+Большинство IMU могут обновлять данные с разной частотой. В полетных контроллерах обычно используется частота обновления от 500 Гц до 8 кГц. Чем выше частота сэмплов, тем выше точность управления полетом, но и больше нагрузка на микроконтроллер.
 
-Частота сэмплирования устанавливается методом `setSampleRate()`. В Flix используется частота 1 кГц:
+Частота сэмплов устанавливается методом `setSampleRate()`. В Flix используется частота 1 кГц:
 
 ```cpp
 IMU.setRate(IMU.RATE_1KHZ_APPROX);
 ```
 
-Поскольку не все поддерживаемые IMU могут работать строго на частоте 1 кГц, в библиотеке FlixPeriph существует возможность приближенной настройки частоты сэмплирования. Например, у IMU ICM-20948 при такой настройке реальная частота сэмплирования будет равна 1125 Гц.
+Поскольку не все поддерживаемые IMU могут работать строго на частоте 1 кГц, в библиотеке FlixPeriph существует возможность приближенной настройки частоты сэмплов. Например, у IMU ICM-20948 при такой настройке реальная частота сэмплирования будет равна 1125 Гц.
 
 Другие доступные для установки в библиотеке FlixPeriph частоты сэмплирования:
 
-* `RATE_MIN` — минимальная частота для конкретного IMU.
+* `RATE_MIN` — минимальная частота сэмплов для конкретного IMU.
 * `RATE_50HZ_APPROX` — значение, близкое к 50 Гц.
 * `RATE_1KHZ_APPROX` — значение, близкое к 1 кГц.
 * `RATE_8KHZ_APPROX` — значение, близкое к 8 кГц.
-* `RATE_MAX` — максимальная частота для конкретного IMU.
+* `RATE_MAX` — максимальная частота сэмплов для конкретного IMU.
 
 #### Диапазон измерений
 
-Большинство MEMS-гироскопов поддерживают несколько диапазонов измерений угловой скорости. Главное преимущество выбора меньшего диапазона — бо́льшая чувствительность. В полетных контроллерах обычно выбирается максимальный диапазон измерений от –2000 до 2000 градусов в секунду, чтобы обеспечить возможность быстрых маневров.
+Большинство MEMS-гироскопов поддерживают несколько диапазонов измерений угловой скорости. Главное преимущество выбора меньшего диапазона — бо́льшая чувствительность. В полетных контроллерах обычно выбирается максимальный диапазон измерений от –2000 до 2000 градусов в секунду, чтобы обеспечить возможность динамичных маневров.
 
 В библиотеке FlixPeriph диапазон измерений гироскопа устанавливается методом `setGyroRange()`:
 
 ```cpp
-imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
+IMU.setGyroRange(IMU.GYRO_RANGE_2000DPS);
 ```
 
 ### LPF-фильтр
@@ -172,16 +172,16 @@ imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
 IMU InvenSense могут фильтровать измерения на аппаратном уровне при помощи фильтра нижних частот (LPF). Flix реализует собственный фильтр для гироскопа, чтобы иметь больше гибкости при поддержке разных IMU. Поэтому для встроенного LPF устанавливается максимальная частота среза:
 
 ```cpp
-imu.setDLPF(imu.DLPF_MAX);
+IMU.setDLPF(IMU.DLPF_MAX);
 ```
 
 ## Калибровка гироскопа
 
-Как и любое измерительное устройство, гироскоп вносит искажения в измерения. Наиболее простая модель этих искажений делит их на статические смещения *(bias)* и случайный шум *(noise)*:
+Как и любое измерительное устройство, гироскоп вносит искажения в измерения. Наиболее простая модель этих искажений делит их на статические смещения (*bias*) и случайный шум (*noise*):
 
 \\[ gyro_{xyz}=rates_{xyz}+bias_{xyz}+noise \\]
 
-Для точной работы подсистемы оценки ориентации и управления дроном необходимо оценить *bias* гироскопа и учесть его в вычислениях. Для этого при запуске программы производится калибровка гироскопа, которая реализована в функции `calibrateGyro()`. Эта функция считывает данные с гироскопа в состоянии покоя 1000 раз и усредняет их. Полученные значения считаются *bias* гироскопа и в дальнейшем вычитаются из измерений.
+Для качественной работы подсистемы оценки ориентации и управления дроном необходимо оценить *bias* гироскопа и учесть его в вычислениях. Для этого при запуске программы производится калибровка гироскопа, которая реализована в функции `calibrateGyro()`. Эта функция считывает данные с гироскопа в состоянии покоя 1000 раз и усредняет их. Полученные значения считаются *bias* гироскопа и в дальнейшем вычитаются из измерений.
 
 Программа для вывода данных с гироскопа с калибровкой:
 
@@ -189,23 +189,23 @@ imu.setDLPF(imu.DLPF_MAX);
 #include <FlixPeriph.h>
 #include <SPI.h>
 
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
 
 float gyroBiasX, gyroBiasY, gyroBiasZ; // bias гироскопа
 
 void setup() {
 	Serial.begin(115200);
-	bool success = imu.begin();
+	bool success = IMU.begin();
 	if (!success) {
-		Serial.println("Failed to initialize the IMU");
+		Serial.println("Failed to initialize IMU");
 	}
 	calibrateGyro();
 }
 
 void loop() {
 	float gx, gy, gz;
-	imu.waitForData();
+	IMU.waitForData();
-	imu.getGyro(gx, gy, gz);
+	IMU.getGyro(gx, gy, gz);
 
 	// Устранение bias гироскопа
 	gx -= gyroBiasX;
@@ -226,9 +226,9 @@ void calibrateGyro() {
 
 	// Получение 1000 измерений гироскопа
 	for (int i = 0; i < samples; i++) {
-		imu.waitForData();
+		IMU.waitForData();
 		float gx, gy, gz;
-		imu.getGyro(gx, gy, gz);
+		IMU.getGyro(gx, gy, gz);
 		gyroBiasX += gx;
 		gyroBiasY += gy;
 		gyroBiasZ += gz;

docs/build.md

@@ -1,2 +1,205 @@
-<!-- markdownlint-disable MD041 -->
+# Building and running
-Build instructions are moved to [usage article](usage.md).
+
+To build the firmware or the simulator, you need to clone the repository using git:
+
+```bash
+git clone https://github.com/okalachev/flix.git
+cd flix
+```
+
+## Simulation
+
+### Ubuntu
+
+The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you have a newer version, consider using a virtual machine.
+
+1. Install Arduino CLI:
+
+   ```bash
+   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
+   ```
+
+2. Install Gazebo 11:
+
+   ```bash
+   curl -sSL http://get.gazebosim.org | sh
+   ```
+
+   Set up your Gazebo environment variables:
+
+   ```bash
+   echo "source /usr/share/gazebo/setup.sh" >> ~/.bashrc
+   source ~/.bashrc
+   ```
+
+3. Install SDL2 and other dependencies:
+
+   ```bash
+   sudo apt-get update && sudo apt-get install build-essential libsdl2-dev
+   ```
+
+4. Add your user to the `input` group to enable joystick support (you need to re-login after this command):
+
+   ```bash
+   sudo usermod -a -G input $USER
+   ```
+
+5. Run the simulation:
+
+   ```bash
+   make simulator
+   ```
+
+### macOS
+
+1. Install Homebrew package manager, if you don't have it installed:
+
+   ```bash
+   /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
+   ```
+
+2. Install Arduino CLI, Gazebo 11 and SDL2:
+
+   ```bash
+   brew tap osrf/simulation
+   brew install arduino-cli
+   brew install gazebo11
+   brew install sdl2
+   ```
+
+   Set up your Gazebo environment variables:
+
+   ```bash
+   echo "source /opt/homebrew/share/gazebo/setup.sh" >> ~/.zshrc
+   source ~/.zshrc
+   ```
+
+3. Run the simulation:
+
+   ```bash
+   make simulator
+   ```
+
+### Setup and flight
+
+#### Control with smartphone
+
+1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone. For **iOS**, use [QGroundControl build from TAJISOFT](https://apps.apple.com/ru/app/qgc-from-tajisoft/id1618653051).
+2. Connect your smartphone to the same Wi-Fi network as the machine running the simulator.
+3. If you're using a virtual machine, make sure that its network is set to the **bridged** mode with Wi-Fi adapter selected.
+4. Run the simulation.
+5. Open QGroundControl app. It should connect and begin showing the virtual drone's telemetry automatically.
+6. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
+7. Use the virtual joystick to fly the drone!
+
+#### Control with USB remote control
+
+1. Connect your USB remote control to the machine running the simulator.
+2. Run the simulation.
+3. Calibrate the RC using `cr` command in the command line interface.
+4. Run the simulation again.
+5. Use the USB remote control to fly the drone!
+
+## Firmware
+
+### Arduino IDE (Windows, Linux, macOS)
+
+1. Install [Arduino IDE](https://www.arduino.cc/en/software) (version 2 is recommended).
+2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
+3. Install ESP32 core, version 3.2.0. See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
+4. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
+   * `FlixPeriph`, the latest version.
+   * `MAVLink`, version 2.0.16.
+5. Clone the project using git or [download the source code as a ZIP archive](https://codeload.github.com/okalachev/flix/zip/refs/heads/master).
+6. Open the downloaded Arduino sketch `flix/flix.ino` in Arduino IDE.
+7. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
+8. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
+
+### Command line (Windows, Linux, macOS)
+
+1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
+
+   On Linux, use:
+
+   ```bash
+   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
+   ```
+
+2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
+3. Compile the firmware using `make`. Arduino dependencies will be installed automatically:
+
+   ```bash
+   make
+   ```
+
+   You can flash the firmware to the board using command:
+
+   ```bash
+   make upload
+   ```
+
+   You can also compile the firmware, upload it and start serial port monitoring using command:
+
+   ```bash
+   make upload monitor
+   ```
+
+See other available Make commands in the [Makefile](../Makefile).
+
+> [!TIP]
+> You can test the firmware on a bare ESP32 board without connecting IMU and other peripherals. The Wi-Fi network `flix` should appear and all the basic functionality including CLI and QGroundControl connection should work.
+
+### Setup and flight
+
+Before flight you need to calibrate the accelerometer:
+
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
+2. Type `ca` command there and follow the instructions.
+
+#### Control with smartphone
+
+1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone.
+2. Power the drone using the battery.
+3. Connect your smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
+4. Open QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
+5. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
+6. Use the virtual joystick to fly the drone!
+
+#### Control with remote control
+
+Before flight using remote control, you need to calibrate it:
+
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
+2. Type `cr` command there and follow the instructions.
+3. Use the remote control to fly the drone!
+
+#### Control with USB remote control
+
+If your drone doesn't have RC receiver installed, you can use USB remote control and QGroundControl app to fly it.
+
+1. Install [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html) app on your computer.
+2. Connect your USB remote control to the computer.
+3. Power up the drone.
+4. Connect your computer to the appeared `flix` Wi-Fi network (password: `flixwifi`).
+5. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
+6. Go the the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate you USB remote control there.
+7. Use the USB remote control to fly the drone!
+
+#### Adjusting parameters
+
+You can adjust some of the drone's parameters (include PID coefficients) in QGroundControl app. In order to do that, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Parameters*.
+
+<img src="img/parameters.png" width="400">
+
+#### CLI access
+
+In addition to accessing the drone's command line interface (CLI) using the serial port, you can also access it with QGroundControl using Wi-Fi connection. To do that, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
+
+<img src="img/cli.png" width="400">
+
+> [!NOTE]
+> If something goes wrong, go to the [Troubleshooting](troubleshooting.md) article.
+
+### Firmware code structure
+
+See [firmware overview](firmware.md) for more details.

docs/firmware.md

@@ -1,104 +1,39 @@
 # Firmware overview
 
-The firmware is a regular Arduino sketch, and it follows the classic Arduino one-threaded design. The initialization code is in the `setup()` function, and the main loop is in the `loop()` function. The sketch includes several files, each responsible for a specific subsystem.
+The firmware is a regular Arduino sketch, and follows the classic Arduino one-threaded design. The initialization code is in the `setup()` function, and the main loop is in the `loop()` function. The sketch includes multiple files, each responsible for a specific part of the system.
 
 ## Dataflow
 
-<img src="img/dataflow.svg" width=600 alt="Firmware dataflow diagram">
+<img src="img/dataflow.svg" width=800 alt="Firmware dataflow diagram">
 
-The main loop is running at 1000 Hz. The dataflow goes through global variables, including:
+The main loop is running at 1000 Hz. All the dataflow is happening through global variables (for simplicity):
 
-* `t` *(float)* — current step time, *s*.
+* `t` *(double)* — current step time, *s*.
 * `dt` *(float)* — time delta between the current and previous steps, *s*.
 * `gyro` *(Vector)* — data from the gyroscope, *rad/s*.
 * `acc` *(Vector)* — acceleration data from the accelerometer, *m/s<sup>2</sup>*.
 * `rates` *(Vector)* — filtered angular rates, *rad/s*.
 * `attitude` *(Quaternion)* — estimated attitude (orientation) of drone.
-* `controlRoll`, `controlPitch`, `controlYaw`, `controlThrottle`, `controlMode` *(float)* — pilot control inputs, range [-1, 1].
+* `controlRoll`, `controlPitch`, ... *(float[])* — pilot's control inputs, range [-1, 1].
-* `motors` *(float[4])* — motor outputs, range [0, 1].
+* `motors` *(float[])* — motor outputs, range [0, 1].
 
 ## Source files
 
-Firmware source files are located in `flix` directory.
+Firmware source files are located in `flix` directory. The key files are:
 
-* [`flix.ino`](../flix/flix.ino) — Arduino sketch main file, entry point.Includes some global variable definitions and the main loop.
+* [`flix.ino`](../flix/flix.ino) — main entry point, Arduino sketch. Includes global variables definition and the main loop.
 * [`imu.ino`](../flix/imu.ino) — reading data from the IMU sensor (gyroscope and accelerometer), IMU calibration.
 * [`rc.ino`](../flix/rc.ino) — reading data from the RC receiver, RC calibration.
-* [`estimate.ino`](../flix/estimate.ino) — attitude estimation, complementary filter.
+* [`estimate.ino`](../flix/estimate.ino) — drone's attitude estimation, complementary filter.
-* [`control.ino`](../flix/control.ino) — control subsystem, three-dimensional two-level cascade PID controller.
+* [`control.ino`](../flix/control.ino) — drone's attitude and rates control, three-dimensional two-level cascade PID controller.
-* [`motors.ino`](../flix/motors.ino) — PWM motor output control.
+* [`motors.ino`](../flix/motors.ino) — PWM motor outputs control.
-* [`mavlink.ino`](../flix/mavlink.ino) — interaction with QGroundControl or [pyflix](../tools/pyflix) via MAVLink protocol.
-* [`cli.ino`](../flix/cli.ino) — serial and MAVLink console.
 
-Utility files:
+Utility files include:
 
-* [`vector.h`](../flix/vector.h), [`quaternion.h`](../flix/quaternion.h) — vector and quaternion libraries.
+* [`vector.h`](../flix/vector.h), [`quaternion.h`](../flix/quaternion.h) — project's vector and quaternion libraries implementation.
-* [`pid.h`](../flix/pid.h) — generic PID controller.
+* [`pid.h`](../flix/pid.h) — generic PID controller implementation.
-* [`lpf.h`](../flix/lpf.h) — generic low-pass filter.
+* [`lpf.h`](../flix/lpf.h) — generic low-pass filter implementation.
 
-### Control subsystem
+## Building
 
-Pilot inputs are interpreted in `interpretControls()`, and then converted to the **control command**, which consists of the following:
+See build instructions in [build.md](build.md).
-
-* `attitudeTarget` *(Quaternion)* — target attitude of the drone.
-* `ratesTarget` *(Vector)* — target angular rates, *rad/s*.
-* `ratesExtra` *(Vector)* — additional (feed-forward) angular rates, used for yaw rate control in STAB mode, *rad/s*.
-* `torqueTarget` *(Vector)* — target torque, range [-1, 1].
-* `thrustTarget` *(float)* — collective motor thrust target, range [0, 1].
-
-Control command is handled in `controlAttitude()`, `controlRates()`, `controlTorque()` functions. Each function may be skipped if the corresponding control target is set to `NAN`.
-
-<img src="img/control.svg" width=300 alt="Control subsystem diagram">
-
-Armed state is stored in `armed` variable, and current mode is stored in `mode` variable.
-
-### Console
-
-To write into the console, `print()` function is used. This function sends data both to the Serial console and to the MAVLink console (which can be accessed wirelessly in QGroundControl). The function supports formatting:
-
-```cpp
-print("Test value: %.2f\n", testValue);
-```
-
-In order to add a console command, modify the `doCommand()` function in `cli.ino` file.
-
-> [!IMPORTANT]
-> Avoid using delays in in-flight commands, it will **crash** the drone! (The design is one-threaded.)
->
-> For on-the-ground commands, use `pause()` function, instead of `delay()`. This function allows to pause in a way that MAVLink connection will continue working.
-
-### Parameter subsystem
-
-Parameters subsystem (`parameters.ino`) uses standard [Preferences.h](https://docs.espressif.com/projects/arduino-esp32/en/latest/tutorials/preferences.html) ESP32 library to store parameters in non-volatile memory. Each parameter is a regular global variable, which is registered in the `parameters` array.
-
-To add a new parameter:
-
-1. Define a global variable for the parameter, two types are supported: `float` and `int`.
-2. Add an entry to the `parameters` array, with the parameter name, a pointer to the variable, and optionally a callback function to call when the parameter is changed.
-3. Everything else will be handled automatically.
-
-See examples of adding new parameters in commits: [c434107](https://github.com/okalachev/flix/commit/c434107), [a687303](https://github.com/okalachev/flix/commit/a687303).
-
-> [!NOTE]
-> Since all the parameters are internally stored and passed as floats, the safe range for `int` parameters is -16777216 to 16777215.
-
-## Adding a subsystem
-
-To add a new subsystem:
-
-1. Create a new `*.ino` file for your subsystem.
-2. Define setup and loop functions for the subsystem, for example `setupMySubsystem()` and `loopMySubsystem()`.
-3. Use `Rate` class if you need to limit the loop frequency, for example:
-
-    ```cpp
-    Rate mySubsystemRate(100); // 100 Hz
-
-    void loopMySubsystem() {
-    	if (!mySubsystemRate) return;
-    	// Do something...
-    }
-4. Add setup and loop calls in to `setup()` and `loop()` functions in `flix.ino`.
-
-## Building the firmware
-
-See build instructions in [usage.md](usage.md).

docs/img/arming.svg

@@ -1,22 +0,0 @@
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-  <defs>
-    <style>
-      .a {
-        fill: #d5d5d5;
-      }
-
-      .b {
-        fill: #fff;
-      }
-
-      .c {
-        fill: #636363;
-      }
-    </style>
-  </defs>
-  <path class="a" d="M340,159.31c-4.74-86-35.9-128.7-35.9-128.7C288.3,9.53,269.17,2.91,251.87.39s-22.31,7.87-22.31,7.87C201.7,4,170.11,4.19,170.11,4.19S138.51,4,110.65,8.26c0,0-5-10.38-22.3-7.87S51.91,9.53,36.14,30.61c0,0-31.16,42.67-35.9,128.7-2.82,51.08,19.68,55.36,38.43,50.4a60.08,60.08,0,0,0,30.55-19.66c7.51-9,19.64-25.32,34-28,17.28-3.26,33.14-4.77,45.09-4.78l21.82,0,21.81,0c12,0,27.82,1.52,45.09,4.78,14.34,2.71,26.47,19,34,28a60.06,60.06,0,0,0,30.56,19.66C320.29,214.67,342.79,210.39,340,159.31Z"/>
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docs/log.md

@@ -2,7 +2,11 @@
 
 Flix quadcopter uses RAM to store flight log data. The default log capacity is 10 seconds at 100 Hz. This configuration can be adjusted in the `log.ino` file.
 
-To perform log analysis, you need to download the flight log. To to that, ensure you're connected to the drone using Wi-Fi and run the following command:
+To perform log analysis, you need to download the log right after the flight without powering off the drone. Then you can use several tools to analyze the log data.
+
+## Log download
+
+To download the log, connect the ESP32 using USB right after the flight and run the following command:
 
 ```bash
 make log

docs/troubleshooting.md

@@ -4,44 +4,34 @@
 
 Do the following:
 
-* **Check ESP32 core is installed**. Check if the version matches the one used in the [tutorial](usage.md#building-the-firmware).
+* **Check ESP32 core is installed**. Check if the version matches the one used in the [tutorial](build.md#firmware).
-* **Check libraries**. Install all the required libraries from the tutorial. Make sure there are no MPU-9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
+* **Check libraries**. Install all the required libraries from the tutorial. Make sure there are no MPU9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
-* **Check the chosen board**. The correct board to choose in Arduino IDE for ESP32 Mini is *WEMOS D1 MINI ESP32*.
 
 ## The drone doesn't fly
 
 Do the following:
 
-* **Check the battery voltage**. Use a multimeter to measure the battery voltage. The fully charged battery should have about 4.2V.
+* **Check the battery voltage**. Use a multimeter to measure the battery voltage. It should be in range of 3.7-4.2 V.
-* **Check the battery you use has enough discharge current**. The battery should be able to provide 15A of current. So the C-rating for a 1000 mAh battery should be at least 15C (higher is better).
+* **Check if there are some startup errors**. Connect the ESP32 to the computer and check the Serial Monitor output. Use the Reset button to make sure you see the whole ESP32 output.
-* **Check if there are some startup errors**. Connect the ESP32 to the computer and check the Serial Monitor output. Use the Reset button or `reboot` command to see the whole startup output.
 * **Check the baudrate is correct**. If you see garbage characters in the Serial Monitor, make sure the baudrate is set to 115200.
-* **Check if the console is working**. Perform `help` command in Serial Monitor. You should see the list of available commands. You can also access the console using QGroundControl *(Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console)*.
+* **Make sure correct IMU model is chosen**. If using ICM-20948 board, change `MPU9250` to `ICM20948` everywhere in the `imu.ino` file.
+* **Check if the CLI is working**. Perform `help` command in Serial Monitor. You should see the list of available commands. You can also access the CLI using QGroundControl (*Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*).
 * **Configure QGroundControl correctly before connecting to the drone** if you use it to control the drone. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
 * **If QGroundControl doesn't connect**, you might need to disable the firewall and/or VPN on your computer.
-* **Make sure correct IMU model is chosen**. If using ICM-20948/MPU-6050 board, change `MPU9250` to `ICM20948`/`MPU6050` in the `imu.ino` file.
 * **Check the IMU is working**. Perform `imu` command and check its output:
   * The `status` field should be `OK`.
   * The `rate` field should be about 1000 (Hz).
   * The `accel` and `gyro` fields should change as you move the drone.
-* **Check the IMU orientation is set correctly**. If the attitude estimation is rotated, set the correct IMU orientation as described in the [tutorial](usage.md#define-imu-orientation).
 * **Calibrate the accelerometer.** if is wasn't done before. Type `ca` command in Serial Monitor and follow the instructions.
-* **Check the attitude estimation**. Connect to the drone using QGroundControl. Rotate the drone in different orientations and check if the attitude estimation is shown exactly as on the video below:
+* **Check the attitude estimation**. Connect to the drone using QGroundControl. Rotate the drone in different orientations and check if the attitude estimation shown in QGroundControl is correct.
-
+* **Check the IMU orientation is set correctly**. If the attitude estimation is rotated, make sure `rotateIMU` function is defined correctly in `imu.ino` file.
-  <a href="https://youtu.be/yVRN23-GISU"><img width=200 src="https://i3.ytimg.com/vi/yVRN23-GISU/maxresdefault.jpg"></a>
-
-* **Check the IMU output**. Connect to the drone using QGroundControl on your computer. Go to the *Analyze* tab, *MAVLINK Inspector*. Plot the data from the `SCALED_IMU` message. The gyroscope and accelerometer data should change according to the drone movement.
 * **Check the motors type**. Motors with exact 3.7V voltage are needed, not ranged working voltage (3.7V — 6V).
 * **Check the motors**. Perform the following commands using Serial Monitor:
   * `mfr` — should rotate front right motor (counter-clockwise).
   * `mfl` — should rotate front left motor (clockwise).
   * `mrl` — should rotate rear left motor (counter-clockwise).
   * `mrr` — should rotate rear right motor (clockwise).
-* **Check the propeller directions are correct**. Make sure your propeller types (A or B) are installed as on the picture:
+* **Calibrate the RC** if you use it. Type `cr` command in Serial Monitor and follow the instructions.
-
+* **Check the RC data** if you use it. Use `rc` command, `Control` should show correct values between -1 and 1, and between 0 and 1 for the throttle.
-  <img src="img/user/peter_ukhov-2/1.jpg" width="200">
+* **Check the IMU output using QGroundControl**. Connect to the drone using QGroundControl on your computer. Go to the *Analyze* tab, *MAVLINK Inspector*. Plot the data from the `SCALED_IMU` message. The gyroscope and accelerometer data should change according to the drone movement.
-
+* **Check the gyroscope only attitude estimation**. Comment out `applyAcc();` line in `estimate.ino` and check if the attitude estimation in QGroundControl. It should be stable, but only drift very slowly.
-* **If using an SBUS receiver**:
-  * **Define the used GPIO pin** in `RC_RX_PIN` parameter.
-  * **Calibrate the RC** using `cr` command in the console.
-  * **Check the controls** using `rc` command. All the controls should change between -1 and 1, and the throttle between 0 and 1.

docs/usage.md

@@ -1,365 +0,0 @@
-# Usage: build, setup and flight
-
-To fly Flix quadcopter, you need to build the firmware, upload it to the ESP32 board, and set up the drone for flight.
-
-To get the firmware sources, clone the repository using git:
-
-```bash
-git clone https://github.com/okalachev/flix.git && cd flix
-```
-
-Beginners can [download the source code as a ZIP archive](https://github.com/okalachev/flix/archive/refs/heads/master.zip).
-
-## Building the firmware
-
-You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
-
-### Arduino IDE (Windows, Linux, macOS)
-
-<img src="img/arduino-ide.png" width="400" alt="Flix firmware open in Arduino IDE">
-
-1. Install [Arduino IDE](https://www.arduino.cc/en/software) (version 2 is recommended).
-2. *Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).*
-3. Install ESP32 core, version 3.3.10. See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
-4. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
-   * `FlixPeriph`, the latest version.
-   * `MAVLink`, version 2.0.25.
-5. Open the `flix/flix.ino` sketch from downloaded firmware sources in Arduino IDE.
-6. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
-7. Set *Tools* ⇒ *Core Debug Level* to *Error* to see the errors in the serial console. Set *Tools* ⇒ *USB CDC on Boot* to *Enabled* for ESP32-S3/ESP32-C3 boards.
-8. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
-
-### Command line (Windows, Linux, macOS)
-
-1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
-
-   On Linux, install it like this:
-
-   ```bash
-   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
-   ```
-
-2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
-3. Compile the firmware using `make`. Arduino dependencies will be installed automatically:
-
-   ```bash
-   make
-   ```
-
-   You can flash the firmware to the board using command:
-
-   ```bash
-   make upload
-   ```
-
-   You can also compile the firmware, upload it and start serial port monitoring using command:
-
-   ```bash
-   make upload monitor
-   ```
-
-   For ESP32-S3/ESP32-C3 boards, set the appropriate [FQBN](https://docs.arduino.cc/arduino-cli/FAQ/#whats-the-fqbn-string) using `BOARD` parameter:
-
-   ```bash
-   make BOARD=esp32:esp32:esp32s3:DebugLevel=error,FlashSize=4M,CDCOnBoot=cdc upload
-   ```
-
-See other available Make commands in [Makefile](../Makefile).
-
-> [!TIP]
-> You can test the firmware on a bare ESP32 board without connecting IMU and other peripherals. The Wi-Fi network `flix` should appear and all the basic functionality including console and QGroundControl connection should work.
-
-## Before first flight
-
-### Choose the IMU model
-
-In case if using different IMU model than MPU9250, change `imu` variable declaration in the `imu.ino`:
-
-```cpp
-ICM20948 imu(SPI);  // For ICM-20948
-MPU6050 imu(Wire);  // For MPU-6050
-```
-
-### Connect using QGroundControl
-
-QGroundControl is a ground control station software that can be used to monitor and control the drone.
-
-1. Install mobile or desktop version of [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html).
-2. Power up the drone.
-3. Connect your computer or smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
-4. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
-
-> [!TIP]
-> If QGroundControl doesn't connect, try to disable the firewall and/or VPN on your computer, as they may block the connection.
-
-### Access console
-
-The console is a command line interface (CLI) that allows to interact with the drone, change parameters, and perform various actions. There are two ways of accessing the console: using **serial port** or using **QGroundControl (wirelessly)**.
-
-To access the console using serial port:
-
-1. Connect the ESP32 board to the computer using USB cable.
-2. Open Serial Monitor in Arduino IDE (or use `make monitor` in the command line).
-3. In Arduino IDE, make sure the baudrate is set to 115200.
-
-To access the console using QGroundControl:
-
-1. Connect to the drone using QGroundControl app.
-2. Go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
-
-<img src="img/cli.png" width="400">
-
-> [!TIP]
-> Use `help` command to see the list of available commands.
-
-### Access parameters
-
-The drone is configured using parameters. To access and modify them, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Parameters*:
-
-<img src="img/parameters.png" width="400">
-
-You can also work with parameters using `p` command in the console. Parameter names are case-insensitive.
-
-### Define IMU orientation
-
-The IMU orientation (relative to the drone's axes) is defined using the parameters: `IMU_ROT_ROLL`, `IMU_ROT_PITCH`, and `IMU_ROT_YAW`.
-
-The drone has *X* axis pointing forward, *Y* axis pointing left, and *Z* axis pointing up, and the supported IMU boards have *X* axis pointing to the mounting holes side and *Z* axis pointing up from the component side:
-
-<img src="img/imu-axes.png" width="200">
-
-Use the following table to set the parameters for common IMU orientations:
-
-|Orientation|Parameters|Orientation|Parameters|
-|:-:|-|-|-|
-|<img src="img/imu-rot-3.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0    |<img src="img/imu-rot-7.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0|
-|<img src="img/imu-rot-2.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|<img src="img/imu-rot-6.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|
-|<img src="img/imu-rot-1.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|<img src="img/imu-rot-5.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|
-|<img src="img/imu-rot-4.png" width="180"><br>☑️ **Default**|<br>`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|<img src="img/imu-rot-8.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|
-
-### Calibrate accelerometer
-
-Before flight you need to calibrate the accelerometer:
-
-1. Access the console using QGroundControl (recommended) or Serial Monitor.
-2. Type `ca` command there and follow the instructions.
-
-### Setup motors
-
-If using non-default motor pins, set the pin numbers using the parameters: `MOTOR_PIN_FL`, `MOTOR_PIN_FR`, `MOTOR_PIN_RL`, `MOTOR_PIN_RR` (front-left, front-right, rear-left, rear-right respectively).
-
-Certain ESP32 models (such as ESP32-S3 and ESP32-C3) support a lower maximum PWM frequency; on these boards the parameter `MOT_PWM_FREQ` should be set to 38000 Hz.
-
-If using brushless motors and ESCs:
-
-1. Set the appropriate PWM using the parameters: `MOT_PWM_STOP`, `MOT_PWM_MIN`, and `MOT_PWM_MAX` (1000, 1000, and 2000 is typical).
-2. Decrease the PWM frequency using the `MOT_PWM_FREQ` parameter (400 is typical).
-
-> [!CAUTION]
-> **Remove the props when configuring the motors!** If improperly configured, you may not be able to stop them.
-
-### Battery voltage monitoring
-
-ESP32 ADC can measure only up to 3.3 V, so you need to use a voltage divider to monitor the battery voltage. To enable voltage measurement, set the following parameters:
-
-1. `PWR_VOLT_PIN` — GPIO pin number where the voltage divider is connected (*-1* to disable).
-2. `PWR_VOLT_SCALE` — voltage divider coefficient (*2* for two equal resistors).
-
-After this setup, you should see the battery voltage in QGroundControl top panel or using `pw` command in the console.
-
-### Important: check everything works
-
-1. Check the IMU is working: perform `imu` command in the console and check the output:
-
-   * The `status` field should be `OK`.
-   * The `rate` field should be about 1000 (Hz).
-   * The `accel` and `gyro` fields should change as you move the drone.
-   * The `accel bias` and `accel scale` fields should contain calibration parameters (not zeros and ones).
-   * The `gyro bias` field should contain estimated gyro bias (not zeros).
-   * The `landed` field should be `1` when the drone is still on the ground and `0` when you lift it up.
-
-2. Check the attitude estimation: connect to the drone using QGroundControl, rotate the drone in different orientations and check if the attitude estimation shown in QGroundControl is correct. Compare your attitude indicator (in the *large vertical* mode) to the video:
-
-   <a href="https://youtu.be/yVRN23-GISU"><img width=300 src="https://i3.ytimg.com/vi/yVRN23-GISU/maxresdefault.jpg"></a>
-
-3. Perform motor tests. Use the following commands **— remove the propellers before running the tests!**
-
-   * `mfr` — rotate front right motor (counter-clockwise).
-   * `mfl` — rotate front left motor (clockwise).
-   * `mrl` — rotate rear left motor (counter-clockwise).
-   * `mrr` — rotate rear right motor (clockwise).
-
-   Make sure rotation directions and propeller types match the following diagram:
-
-   <img src="img/motors.svg" width=200>
-
-> [!WARNING]
-> Never run the motors when powering the drone from USB, always use the battery for that.
-
-## Setup remote control
-
-There are several ways to control the drone's flight: using **smartphone** (Wi-Fi), using **SBUS remote control**, or using **USB remote control** (Wi-Fi).
-
-### Control with a smartphone
-
-#### Using Mavlink Joystick app (Android)
-
-<img src="https://github.com/goldarte/mavlink-joystick/blob/master/app_screen.png?raw=true" width="400">
-
-1. Download and install [Mavlink Joystick app](https://github.com/goldarte/mavlink-joystick/releases/latest).
-2. Power the drone using the battery.
-3. Connect your smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
-4. Open Mavlink Joystick app. It should connect and begin showing the drone's telemetry automatically.
-5. Use the virtual joystick to fly the drone!
-
-#### Using QGroundControl app
-
-1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone.
-2. Power the drone using the battery.
-3. Connect your smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
-4. Open QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
-5. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
-6. Use the virtual joystick to fly the drone!
-
-> [!TIP]
-> Decrease `CTL_TILT_MAX` parameter when flying using the smartphone to make the controls less sensitive.
-
-### Control with a remote control
-
-If using SBUS-connected remote control you need to enable SBUS and calibrate it:
-
-1. Connect to the drone using QGroundControl.
-2. In parameters, set the `RC_RX_PIN` parameter to the GPIO pin number where the SBUS signal is connected, for example: 4. Negative value disables SBUS.
-3. Check if the receiver is working using `rc` command in the console.
-4. Open the console, type `cr` command and follow the instructions to calibrate the remote control.
-5. Use the remote control to fly the drone!
-
-### Control with a USB remote control
-
-If your drone doesn't have RC receiver installed, you can use USB remote control and QGroundControl app to fly it.
-
-1. Install [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html) app on your computer.
-2. Connect your USB remote control to the computer.
-3. Power up the drone.
-4. Connect your computer to the appeared `flix` Wi-Fi network (password: `flixwifi`).
-5. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
-6. Go the the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate you USB remote control there.
-7. Use the USB remote control to fly the drone!
-
-## Flight
-
-For both virtual sticks and a physical joystick, the default control scheme is left stick for throttle and yaw and right stick for pitch and roll:
-
-<img src="img/controls.svg" width="300">
-
-### Arming and disarming
-
-To start the motors, you should **arm** the drone. To do that, move the left stick to the bottom right corner:
-
-<img src="img/arming.svg" width="150">
-
-After that, the motors **will start spinning** at low speed, indicating that the drone is armed and ready to fly.
-
-When finished flying, **disarm** the drone, moving the left stick to the bottom left corner:
-
-<img src="img/disarming.svg" width="150">
-
-> [!NOTE]
-> If something goes wrong, go to the [Troubleshooting](troubleshooting.md) article.
-
-### Flight modes
-
-Flight mode is changed using mode switch on the remote control (if configured) or using the console commands. The main flight mode is *STAB*. In order to change modes using SBUS remote control, set the parameters: `CTL_FLT_MODE_0`, `CTL_FLT_MODE_1`, and `CTL_FLT_MODE_2` to required mode numbers (0 for *RAW*, 1 for *ACRO*, 2 for *STAB*, 3 for *AUTO*).
-
-#### STAB
-
-In this mode, the drone stabilizes its attitude (orientation). The left stick controls throttle and yaw rate, the right stick controls pitch and roll angles.
-
-> [!IMPORTANT]
-> The drone doesn't stabilize its position, so slight drift is possible. The pilot should compensate it manually.
-
-#### ACRO
-
-In this mode, the pilot controls the angular rates. This control method is difficult to fly and mostly used in FPV racing.
-
-#### RAW
-
-*RAW* mode disables all the stabilization, and the pilot inputs are mixed directly to the motors. The IMU sensor is not involved. This mode is intended for testing and demonstration purposes only, and basically the drone **cannot fly in this mode**.
-
-#### AUTO
-
-In this mode, the pilot inputs are ignored (except the mode switch). The drone can be controlled using [pyflix](../tools/pyflix/) Python library, or by modifying the firmware to implement the needed behavior.
-
-If the pilot moves the control sticks and mode switch is not configured, the drone will switch back to *STAB* mode.
-
-## Wi-Fi configuration
-
-You can configure the Wi-Fi using parameters and console commands.
-
-The Wi-Fi mode is chosen using `WIFI_MODE` parameter in QGroundControl or in the console:
-
-* `0` — Wi-Fi is disabled.
-* `1` — Access Point mode *(AP)* — the drone creates a Wi-Fi network.
-* `2` — Client mode *(STA)* — the drone connects to an existing Wi-Fi network (may cause additional delays, so generally not recommended).
-* `3` — ESP-NOW mode — the drone uses ESP-NOW protocol for communication.
-
-The SSID and password are configured using the `ap` and `sta` console commands:
-
-```
-ap <ssid> <password>
-sta <ssid> <password>
-```
-
-Example of configuring the Access Point mode:
-
-```
-ap my-flix-ssid mypassword123
-p WIFI_MODE 1
-```
-
-Disabling Wi-Fi:
-
-```
-p WIFI_MODE 0
-```
-
-### Using ESP-NOW
-
-[ESP-NOW](https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/network/esp_now.html) is a low level wireless communication protocol. It can provide lower latency, better reliability, and longer range than Wi-Fi. However, it requires a second ESP32 board to be used as a proxy for the computer.
-
-<img src="img/espnow-connection.jpg" width="600">
-
-To setup ESP-NOW communication:
-
-1. Flash the second ESP32 board with ESP-NOW proxy sketch: [`tools/espnow-proxy/espnow-proxy.ino`](../tools/espnow-proxy/espnow-proxy.ino). Use Arduino IDE or command line: `make upload_proxy`.
-
-2. Open Serial Monitor or use `make monitor` command. The ESP32 will print its MAC address and generated encryption key, for example:
-
-   ```
-   espnow 7a:c8:e3:eb:bf:e9 &PiuSysxP9+$L&5E
-   ```
-
-   Run this line as a console command on each drone you want to bind to this proxy board. [The maximum number](https://github.com/espressif/esp-idf/blob/e95cab4be8fd293e3f3323181e7a2280874da6f7/components/esp_wifi/include/esp_now.h#L32-L33) of simultaneously connected drones is 20 (unencrypted) io 6 (encrypted).
-
-3. Set the `WIFI_MODE` parameter to `3` on the drone:
-
-   ```
-   p WIFI_MODE 3
-   ```
-
-4. Go to the QGroundControl menu ⇒ *Application Settings* ⇒ *Comm Links*, add new link with the following settings:
-   * Name: ESP32.
-   * Type: Serial.
-   * Serial Port: choose the port of the proxy ESP32 board, e. g. `/dev/cu.usbserial-0001`.
-   * Baud Rate: 115200.
-5. Click *Save*. QGroundControl should connect to the drone using ESP-NOW and begin showing the telemetry.
-
-## Flight log
-
-After the flight, you can download the flight log for analysis wirelessly. Use the following command on your computer for that:
-
-```bash
-make log
-```
-
-See more details about log analysis in the [log analysis](log.md) article.

docs/user.md

@@ -4,164 +4,6 @@ This page contains user-built drones based on the Flix project. Publish your pro
 
 ---
 
-Author: [Неруш Михаил](https://t.me/NerushMV).<br>
-Description: custom frame made of 4 mm plywood, 8520 brushed motors, 75 mm propellers, MPU-6500. FlySky FS-i6X with ESP32-based adapter for ESP-NOW communication (using PPM output).
-
-<img src="img/user/nerush/1.jpg" height=200> <img src="img/user/nerush/2.jpg" height=200>
-
-[Flight video](https://drive.google.com/file/d/1jRXeGx34lJpUfw0GKLQeIzkWZvooQJSE/view?usp=sharing).
-
----
-
-Author: [Konstantinos Paraskevas](https://github.com/Frapais).<br>
-Description: drone with a custom single-boarded airframe, extending the [Sprig-C3 module](https://github.com/Frapais/Sprig-C3).
-ESP32-C3 microcontroller, ICM-20948 IMU, on-board fuel-gauge, status LED indicator.<br>
-Repository with all the code and PCB sources: https://github.com/Frapais/Sprig-Drone.
-
-<img src="img/user/kostas/1.jpg" height=150> <img src="img/user/kostas/2.jpg" height=150>
-
-Detailed video about making the drone:
-
-<a href="https://youtu.be/82Q-uBq6s48"><img width=400 src="https://i3.ytimg.com/vi/82Q-uBq6s48/maxresdefault.jpg"></a>
-
----
-
-Author: [Awab Anas](http://t.me/AW_VENOM).<br>
-Description: ESP32 D1 Mini, MPU-6050, 8520 3.7V brushed motors, 55 mm propellers, battery li-po 1200 mAh, controlling via [Mavlink Joystick app](https://github.com/goldarte/mavlink-joystick/releases/latest).<br>
-[Flight validation](https://drive.google.com/file/d/12z0jfctZDBA6b5UKCG0Uje5rAxj6DhF-/view?usp=sharing).
-
-<img src="img/user/aw_venom/1.jpg" height=200>
-
----
-
-Author: [Ina Tix](https://t.me/ina_tix).<br>
-Description: XR2981 based DC-DC converter, ELRS MINI 2.4GHz RX SX1280 receiver (SBUS interface), Radiomaster TX12 remote control.<br>
-[Flight validation](https://drive.google.com/file/d/1yqkKNuz4R_yxGqUNQxVpixJbXqEEcUSj/view?usp=share_link).
-
-<img src="img/user/ina_tix/1.jpg" height=200> <img src="img/user/ina_tix/2.jpg" height=200> <img src="img/user/ina_tix/3.jpg" height=200>
-
----
-
-Author: Oleg Kalachev.<br>
-Description: the first attempt on making an official PCB based Flix drone (Flix2 board). The IMU is not working on this version, so an external MPU-6050 board was used, therefore considered as **Flix version 1.5**.<br>
-[Flight video](https://drive.google.com/file/d/1R7tuUsFmPY0CGcOCFfMFaCp9kR49K3bl/view?usp=sharing).
-
-<img src="img/flix1.5.jpg" width=300>
-
----
-
-Author: [FanBy0ru](https://https://github.com/FanBy0ru).<br>
-Description: custom 3D-printed frame.<br>
-Frame STLs and flight validation: https://cults3d.com/en/3d-model/gadget/armature-pour-flix-drone.
-
-<img src="img/user/fanby0ru/1.jpg" height=200> <img src="img/user/fanby0ru/2.jpg" height=200>
-
----
-
-Author: Ivan44 Phalko.<br>
-Description: custom PCB, cusom test bench.<br>
-[Flight validation](https://drive.google.com/file/d/17DNDJ1gPmCmDRAwjedCbJ9RXAyqMqqcX/view?usp=sharing).
-
-<img src="img/user/phalko/1.jpg" height=200> <img src="img/user/phalko/2.jpg" height=200> <img src="img/user/phalko/3.jpg" height=200>
-
----
-
-Author: **Arkadiy "Arky" Matsekh**, Foucault Dynamics, Gold Coast, Australia.<br>
-The drone was built for the University of Queensland industry-led Master's capstone project.
-
-**Flight video:**
-
-<a href="https://drive.google.com/file/d/1NNYSVXBY-w0JjCo07D8-PgnVq3ca9plj/view?usp=sharing"><img height=300 src="img/user/arkymatsekh/video.jpg"></a>
-
-<img src="img/user/arkymatsekh/1.jpg" height=150> <img src="img/user/arkymatsekh/2.jpg" height=150> <img src="img/user/arkymatsekh/3.jpg" height=150>
-
----
-
-Author: [goldarte](https://t.me/goldarte).<br>
-
-<img src="img/user/goldarte/1.jpg" height=150> <img src="img/user/goldarte/2.jpg" height=150>
-
-**Flight video:**
-
-<a href="https://drive.google.com/file/d/1nQtFjEcGGLx-l4xkL5ko9ZpOTVU-WDjL/view?usp=sharing"><img height=200 src="img/user/goldarte/video.jpg"></a>
-
----
-
-Author: [malagis](https://oshwhub.com/malagis).<br>
-
-A Chinese custom PCB version of Flix with a big community of users, lots of materials and modifications.
-
-Main project's page: https://oshwhub.com/malagis/esp32-mini-plane.<br>
-Video about the project: https://www.bilibili.com/video/BV14vyqBFEJn/.
-
-<img src="img/user/malagis/1.jpg" height=200> <img src="img/user/malagis/2.jpg" height=200> <img src="img/user/malagis/3.jpg" height=200>
-
----
-
-## School 548 course
-
-Special course on quadcopter design and engineering took place in october-november 2025 in School 548, Moscow. The course included UAV control theory, electronics, drone assembly and setup practice, using the Flix project.
-
-<img height=200 src="img/user/school548/1.jpg"> <img height=200 src="img/user/school548/2.jpg"> <img height=200 src="img/user/school548/3.jpg">
-
-STL files and other materials: see [here](https://drive.google.com/drive/folders/1wTUzj087LjKQQl3Lz5CjHCuobxoykhyp?usp=share_link).
-
-### Selected works
-
-Author: [KiraFlux](https://t.me/@kiraflux_0XC0000005).<br>
-Description: **custom ESPNOW remote control** was implemented, modified firmware to support ESPNOW protocol.<br>
-Telegram posts: [1](https://t.me/opensourcequadcopter/106), [2](https://t.me/opensourcequadcopter/114).<br>
-Modified Flix firmware: https://github.com/KiraFlux/flix/tree/klyax.<br>
-Remote control project: https://github.com/KiraFlux/ESP32-DJC.<br>
-Drone design: https://github.com/KiraFlux/Klyax.<br>
-
-<img src="img/user/school548/kiraflux1.jpg" height=150> <img src="img/user/school548/kiraflux2.jpg" height=150>
-
-**ESPNOW remote control demonstration**:
-
-<img height=200 src="img/user/school548/kiraflux-video.jpg"><a href="https://drive.google.com/file/d/1soHDAeHQWnm97Y4dg4nWevJuMiTdJJXW/view?usp=sharing"></a>
-
-Author: [tolyan4krut](https://t.me/tolyan4krut).<br>
-Description: the first drone based on ESP32-S3-CAM board **with a camera**, implementing Wi-Fi video streaming. Runs HTTP server and HTTP video stream.<br>
-Modified Flix firmware: https://github.com/CatRey/Flix-Camera-Streaming.<br>
-[Telegram post](https://t.me/opensourcequadcopter/117).
-
-<img src="img/user/school548/tolyan4krut.jpg" height=150>
-
-**Video streaming and flight demonstration**:
-
-<a href="https://drive.google.com/file/d/1KuOBsujLsk7q8FoqKD8u7uoq4ptS5onp/view?usp=sharing"><img height=200 src="img/user/school548/tolyan4krut-video.jpg"></a>
-
-Author: [Vlad Tolshinov](https://t.me/Vlad_Tolshinov).<br>
-Description: custom frame with enlarged arm length, which provides very high flight stability, 65 mm props.
-
-<img src="img/user/school548/vlad_tolshinov1.jpg" height=150> <img src="img/user/school548/vlad_tolshinov2.jpg" height=150>
-
-**Flight video**:
-
-<a href="https://drive.google.com/file/d/1zu00DZxhC7DJ9Z2mYjtxdNQqOOLAyYbp/view?usp=sharing"><img height=200 src="img/user/school548/vlad_tolshinov-video.jpg"></a>
-
----
-
-## RoboCamp
-
-Author: RoboCamp participants.<br>
-Description: 3D-printed and wooden frames, ESP32 Mini, DC-DC buck-boost converters. BetaFPV LiteRadio 3 to control the drones via Wi-Fi connection.<br>
-Features: altitude hold, obstacle avoidance, autonomous flight elements.<br>
-Some of the designed model files: see [here](https://drive.google.com/drive/folders/18YHWGquKeIevzrMH4-OUT-zKXMETTEUu?usp=share_link).
-
-RoboCamp took place in July 2025, Saint Petersburg, where 9 participants designed and built their own drones using the Flix project, and then modified the firmware to complete specific flight tasks.
-
-See the detailed video about the event:
-
-<a href="https://youtu.be/Wd3yaorjTx0"><img width=500 src="https://img.youtube.com/vi/Wd3yaorjTx0/sddefault.jpg"></a>
-
-Built drones:
-
-<img src="img/user/robocamp/1.jpg" width=500>
-
----
-
 Author: chkroko.<br>
 Description: the first Flix drone built with **brushless motors** (DShot interface).<br>
 Features: SpeedyBee BLS 35A Mini V2 ESC, ESP32-S3 board, EMAX ECO 2 2207 1700kv motors, ICM20948V2 IMU, INA226 power monitor and Bluetooth gamepad for control.<br>

docs/version0.md

@@ -14,7 +14,7 @@ Flix version 0 (obsolete):
 |Motor|8520 3.7V brushed motor (**shaft 0.8mm!**)|<img src="img/motor.jpeg" width=100>|4|
 |Propeller|Hubsan 55 mm|<img src="img/prop.jpg" width=100>|4|
 |Motor ESC|2.7A 1S Dual Way Micro Brush ESC|<img src="img/esc.jpg" width=100>|4|
-|RC transmitter|KINGKONG TINY X8|<img src="img/kingkong.jpg" width=100>|1|
+|RC transmitter|KINGKONG TINY X8|<img src="img/tx.jpg" width=100>|1|
 |RC receiver|DF500 (SBUS)|<img src="img/rx.jpg" width=100>|1|
 |~~SBUS inverter~~*||<img src="img/inv.jpg" width=100>|~~1~~|
 |Battery|3.7 Li-Po 850 MaH 60C|||

flix/cli.ino

@@ -6,72 +6,64 @@
 #include "pid.h"
 #include "vector.h"
 #include "util.h"
-#include "lpf.h"
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
-extern const int RAW, ACRO, STAB, AUTO;
+extern float loopRate, dt;
-extern const int W_AP, W_STA, W_ESPNOW;
+extern double t;
-extern float t, dt, loopRate;
 extern uint16_t channels[16];
-extern float controlTime;
+extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlArmed, controlMode;
-extern int mode;
 extern bool armed;
-extern LowPassFilter<Vector> gyroBiasFilter;
-extern float voltage;
 
 const char* motd =
+"\nWelcome to\n"
 " _______  __       __  ___   ___\n"
 "|   ____||  |     |  | \\  \\ /  /\n"
 "|  |__   |  |     |  |  \\  V  /\n"
 "|   __|  |  |     |  |   >   <\n"
 "|  |     |  `----.|  |  /  .  \\\n"
 "|__|     |_______||__| /__/ \\__\\\n\n"
-"(C) Oleg Kalachev\n"
-"https://github.com/okalachev/flix\n\n"
 "Commands:\n\n"
 "help - show help\n"
 "p - show all parameters\n"
-"p <str> - show parameters starting with str\n"
+"p <name> - show parameter\n"
 "p <name> <value> - set parameter\n"
 "preset - reset parameters\n"
 "time - show time info\n"
+"ps - show pitch/roll/yaw\n"
+"psq - show attitude quaternion\n"
 "imu - show IMU data\n"
-"ca - calibrate accel\n"
+"arm - arm the drone (when no mode switch)\n"
-"st - show state estimation\n"
+"disarm - disarm the drone (when no mode switch)\n"
-"arm - arm the drone\n"
-"disarm - disarm the drone\n"
-"raw/stab/acro/auto - set mode\n"
 "rc - show RC data\n"
-"cr - calibrate RC\n"
-"pw - show power info\n"
-"wifi - show Wi-Fi info\n"
-"wifi ap/sta/espnow/off - set Wi-Fi mode\n"
-"ap <ssid> <password> - configure Wi-Fi access point\n"
-"sta <ssid> <password> - configure Wi-Fi client mode\n"
-"espnow <mac> [<key>] - configure ESP-NOW peer\n"
 "mot - show motor output\n"
-"log [dump] - print log header [and data]\n"
+"log - dump in-RAM log\n"
+"cr - calibrate RC\n"
+"ca - calibrate accel\n"
 "mfr, mfl, mrr, mrl - test motor (remove props)\n"
 "sys - show system info\n"
 "reset - reset drone's state\n"
 "reboot - reboot the drone\n";
 
 void print(const char* format, ...) {
-	char buf[3000];
+	char buf[1000];
 	va_list args;
 	va_start(args, format);
 	vsnprintf(buf, sizeof(buf), format, args);
 	va_end(args);
 	Serial.print(buf);
+#if WIFI_ENABLED
 	mavlinkPrint(buf);
+#endif
 }
 
 void pause(float duration) {
-	float start = t;
+	double start = t;
 	while (t - start < duration) {
 		step();
 		handleInput();
+#if WIFI_ENABLED
 		processMavlink();
+#endif
 		delay(50);
 	}
 }
@@ -80,10 +72,9 @@ void doCommand(String str, bool echo = false) {
 	// parse command
 	String command, arg0, arg1;
 	splitString(str, command, arg0, arg1);
-	if (command.isEmpty()) return;
 
 	// echo command
-	if (echo) {
+	if (echo && !command.isEmpty()) {
 		print("> %s\n", str.c_str());
 	}
 
@@ -92,12 +83,14 @@ void doCommand(String str, bool echo = false) {
 	// execute command
 	if (command == "help" || command == "motd") {
 		print("%s\n", motd);
-	} else if (command == "p" && arg1 == "") {
+	} else if (command == "p" && arg0 == "") {
-		printParameters(arg0.c_str());
+		printParameters();
+	} else if (command == "p" && arg0 != "" && arg1 == "") {
+		print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
 	} else if (command == "p") {
 		bool success = setParameter(arg0.c_str(), arg1.toFloat());
 		if (success) {
-			print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
+			print("%s = %g\n", arg0.c_str(), arg1.toFloat());
 		} else {
 			print("Parameter not found: %s\n", arg0.c_str());
 		}
@@ -107,55 +100,35 @@ void doCommand(String str, bool echo = false) {
 		print("Time: %f\n", t);
 		print("Loop rate: %.0f\n", loopRate);
 		print("dt: %f\n", dt);
+	} else if (command == "ps") {
+		Vector a = attitude.toEuler();
+		print("roll: %f pitch: %f yaw: %f\n", degrees(a.x), degrees(a.y), degrees(a.z));
+	} else if (command == "psq") {
+		print("qx: %f qy: %f qz: %f qw: %f\n", attitude.x, attitude.y, attitude.z, attitude.w);
 	} else if (command == "imu") {
 		printIMUInfo();
+		print("gyro: %f %f %f\n", rates.x, rates.y, rates.z);
+		print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
 		printIMUCalibration();
-		print("landed: %d\n", landed);
+		print("rate: %.0f\n", loopRate);
-	} else if (command == "st") {
-		print("rates: %g %g %g\n", rates.x, rates.y, rates.z);
-		print("attitude: %g %g %g %g\n", attitude.w, attitude.x, attitude.y, attitude.z);
-		print("roll: %g° pitch: %g° yaw: %g°\n", degrees(attitude.getRoll()), degrees(attitude.getPitch()), degrees(attitude.getYaw()));
 		print("landed: %d\n", landed);
 	} else if (command == "arm") {
 		armed = true;
 	} else if (command == "disarm") {
 		armed = false;
-	} else if (command == "raw") {
-		mode = RAW;
-	} else if (command == "stab") {
-		mode = STAB;
-	} else if (command == "acro") {
-		mode = ACRO;
-	} else if (command == "auto") {
-		mode = AUTO;
 	} else if (command == "rc") {
 		print("channels: ");
 		for (int i = 0; i < 16; i++) {
 			print("%u ", channels[i]);
 		}
-		print("\nroll: %g pitch: %g yaw: %g throttle: %g mode: %g\n",
+		print("\nroll: %g pitch: %g yaw: %g throttle: %g armed: %g mode: %g\n",
-			controlRoll, controlPitch, controlYaw, controlThrottle, controlMode);
+			controlRoll, controlPitch, controlYaw, controlThrottle, controlArmed, controlMode);
-		print("time: %.1f\n", controlTime);
 		print("mode: %s\n", getModeName());
-		print("armed: %d\n", armed);
-	} else if (command == "pw") {
-		print("Voltage: %.1f V\n", voltage);
-	} else if (command == "wifi" && arg0 == "") {
-		printWiFiInfo();
-	} else if (command == "wifi") {
-		setWiFiMode(arg0);
-	} else if (command == "ap") {
-		configWiFi(W_AP, arg0.c_str(), arg1.c_str());
-	} else if (command == "sta") {
-		configWiFi(W_STA, arg0.c_str(), arg1.c_str());
-	} else if (command == "espnow") {
-		configWiFi(W_ESPNOW, arg0.c_str(), arg1.c_str());
 	} else if (command == "mot") {
 		print("front-right %g front-left %g rear-right %g rear-left %g\n",
 			motors[MOTOR_FRONT_RIGHT], motors[MOTOR_FRONT_LEFT], motors[MOTOR_REAR_RIGHT], motors[MOTOR_REAR_LEFT]);
 	} else if (command == "log") {
-		printLogHeader();
+		dumpLog();
-		if (arg0 == "dump") printLogData();
 	} else if (command == "cr") {
 		calibrateRC();
 	} else if (command == "ca") {
@@ -172,11 +145,9 @@ void doCommand(String str, bool echo = false) {
 #ifdef ESP32
 		print("Chip: %s\n", ESP.getChipModel());
 		print("Temperature: %.1f °C\n", temperatureRead());
-		print("Total RAM: %d KB\n", ESP.getHeapSize() / 1024);
+		print("Free heap: %d\n", ESP.getFreeHeap());
-		print("Free heap: %d KB\n", ESP.getFreeHeap() / 1024);
-		print("Firmware: " __DATE__ " " __TIME__ "\n");
 		// Print tasks table
-		print("Num  Task                MinSt  Prio  Core  CPU%%\n");
+		print("Num  Task                Stack  Prio  Core  CPU%%\n");
 		int taskCount = uxTaskGetNumberOfTasks();
 		TaskStatus_t *systemState = new TaskStatus_t[taskCount];
 		uint32_t totalRunTime;
@@ -185,15 +156,16 @@ void doCommand(String str, bool echo = false) {
 			String core = systemState[i].xCoreID == tskNO_AFFINITY ? "*" : String(systemState[i].xCoreID);
 			int cpuPercentage = systemState[i].ulRunTimeCounter / (totalRunTime / 100);
 			print("%-5d%-20s%-7d%-6d%-6s%d\n",systemState[i].xTaskNumber, systemState[i].pcTaskName,
-				systemState[i].usStackHighWaterMark, systemState[i].uxCurrentPriority, core.c_str(), cpuPercentage);
+				systemState[i].usStackHighWaterMark, systemState[i].uxCurrentPriority, core, cpuPercentage);
 		}
 		delete[] systemState;
 #endif
 	} else if (command == "reset") {
 		attitude = Quaternion();
-		gyroBiasFilter.reset();
 	} else if (command == "reboot") {
 		ESP.restart();
+	} else if (command == "") {
+		// do nothing
 	} else {
 		print("Invalid command: %s\n", command.c_str());
 	}
@@ -210,7 +182,7 @@ void handleInput() {
 
 	while (Serial.available()) {
 		char c = Serial.read();
-		if (c == '\n' || c == '\r') {
+		if (c == '\n') {
 			doCommand(input);
 			input.clear();
 		} else {

flix/control.ino

@@ -34,16 +34,9 @@
 #define TILT_MAX radians(30)
 #define RATES_D_LPF_ALPHA 0.2 // cutoff frequency ~ 40 Hz
 
-const int RAW = 0, ACRO = 1, STAB = 2, AUTO = 3; // flight modes
+enum { MANUAL, ACRO, STAB, AUTO } mode = STAB;
-int mode = STAB;
 bool armed = false;
 
-Quaternion attitudeTarget;
-Vector ratesTarget;
-Vector ratesExtra; // feedforward rates
-Vector torqueTarget;
-float thrustTarget;
-
 PID rollRatePID(ROLLRATE_P, ROLLRATE_I, ROLLRATE_D, ROLLRATE_I_LIM, RATES_D_LPF_ALPHA);
 PID pitchRatePID(PITCHRATE_P, PITCHRATE_I, PITCHRATE_D, PITCHRATE_I_LIM, RATES_D_LPF_ALPHA);
 PID yawRatePID(YAWRATE_P, YAWRATE_I, YAWRATE_D);
@@ -52,10 +45,15 @@ PID pitchPID(PITCH_P, PITCH_I, PITCH_D);
 PID yawPID(YAW_P, 0, 0);
 Vector maxRate(ROLLRATE_MAX, PITCHRATE_MAX, YAWRATE_MAX);
 float tiltMax = TILT_MAX;
-int flightModes[] = {STAB, STAB, STAB}; // map for rc mode switch
+
+Quaternion attitudeTarget;
+Vector ratesTarget;
+Vector ratesExtra; // feedforward rates
+Vector torqueTarget;
+float thrustTarget;
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
-extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlMode;
+extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlArmed, controlMode;
 
 void control() {
 	interpretControls();
@@ -66,42 +64,47 @@ void control() {
 }
 
 void interpretControls() {
-	if (controlMode < 0.25) mode = flightModes[0];
+	// NOTE: put ACRO or MANUAL modes there if you want to use them
-	else if (controlMode <= 0.75) mode = flightModes[1];
+	if (controlMode < 0.25) mode = STAB;
-	else if (controlMode > 0.75) mode = flightModes[2];
+	if (controlMode < 0.75) mode = STAB;
+	if (controlMode > 0.75) mode = AUTO;
+	if (controlArmed < 0.5) armed = false;
 
 	if (mode == AUTO) return; // pilot is not effective in AUTO mode
 
-	if (controlThrottle < 0.05 && controlYaw > 0.95) armed = true; // arm gesture
+	if (landed && controlThrottle == 0 && controlYaw > 0.95) armed = true; // arm gesture
-	if (controlThrottle < 0.05 && controlYaw < -0.95) armed = false; // disarm gesture
+	if (landed && controlThrottle == 0 && controlYaw < -0.95) armed = false; // disarm gesture
-
-	if (abs(controlYaw) < 0.1) controlYaw = 0; // yaw dead zone
 
 	thrustTarget = controlThrottle;
 
 	if (mode == STAB) {
 		float yawTarget = attitudeTarget.getYaw();
-		if (!armed || invalid(yawTarget) || controlYaw != 0) yawTarget = attitude.getYaw(); // reset yaw target
+		if (invalid(yawTarget) || controlYaw != 0) yawTarget = attitude.getYaw(); // reset yaw target if NAN or yaw rate is set
 		attitudeTarget = Quaternion::fromEuler(Vector(controlRoll * tiltMax, controlPitch * tiltMax, yawTarget));
 		ratesExtra = Vector(0, 0, -controlYaw * maxRate.z); // positive yaw stick means clockwise rotation in FLU
 	}
 
 	if (mode == ACRO) {
-		attitudeTarget.invalidate(); // skip attitude control
+		attitudeTarget.invalidate();
 		ratesTarget.x = controlRoll * maxRate.x;
 		ratesTarget.y = controlPitch * maxRate.y;
 		ratesTarget.z = -controlYaw * maxRate.z; // positive yaw stick means clockwise rotation in FLU
 	}
 
-	if (mode == RAW) { // direct torque control
+	if (mode == MANUAL) { // passthrough mode
-		attitudeTarget.invalidate(); // skip attitude control
+		attitudeTarget.invalidate();
-		ratesTarget.invalidate(); // skip rate control
+		ratesTarget.invalidate();
-		torqueTarget = Vector(controlRoll, controlPitch, -controlYaw) * 0.1;
+		torqueTarget = Vector(controlRoll, controlPitch, -controlYaw) * 0.01;
 	}
 }
 
 void controlAttitude() {
-	if (!armed || attitudeTarget.invalid() || thrustTarget < 0.1) return; // skip attitude control
+	if (!armed || attitudeTarget.invalid()) { // skip attitude control
+		rollPID.reset();
+		pitchPID.reset();
+		yawPID.reset();
+		return;
+	}
 
 	const Vector up(0, 0, 1);
 	Vector upActual = Quaternion::rotateVector(up, attitude);
@@ -109,38 +112,34 @@ void controlAttitude() {
 
 	Vector error = Vector::rotationVectorBetween(upTarget, upActual);
 
-	ratesTarget.x = rollPID.update(error.x) + ratesExtra.x;
+	ratesTarget.x = rollPID.update(error.x, dt) + ratesExtra.x;
-	ratesTarget.y = pitchPID.update(error.y) + ratesExtra.y;
+	ratesTarget.y = pitchPID.update(error.y, dt) + ratesExtra.y;
 
 	float yawError = wrapAngle(attitudeTarget.getYaw() - attitude.getYaw());
-	ratesTarget.z = yawPID.update(yawError) + ratesExtra.z;
+	ratesTarget.z = yawPID.update(yawError, dt) + ratesExtra.z;
 }
 
-
 void controlRates() {
-	if (!armed || ratesTarget.invalid() || thrustTarget < 0.1) return; // skip rates control
+	if (!armed || ratesTarget.invalid()) { // skip rates control
+		rollRatePID.reset();
+		pitchRatePID.reset();
+		yawRatePID.reset();
+		return;
+	}
 
 	Vector error = ratesTarget - rates;
 
 	// Calculate desired torque, where 0 - no torque, 1 - maximum possible torque
-	torqueTarget.x = rollRatePID.update(error.x);
+	torqueTarget.x = rollRatePID.update(error.x, dt);
-	torqueTarget.y = pitchRatePID.update(error.y);
+	torqueTarget.y = pitchRatePID.update(error.y, dt);
-	torqueTarget.z = yawRatePID.update(error.z);
+	torqueTarget.z = yawRatePID.update(error.z, dt);
 }
 
 void controlTorque() {
 	if (!torqueTarget.valid()) return; // skip torque control
 
-	if (!armed) {
+	if (!armed || thrustTarget < 0.05) {
-		memset(motors, 0, sizeof(motors)); // stop motors if disarmed
+		memset(motors, 0, sizeof(motors));
-		return;
-	}
-
-	if (thrustTarget < 0.1) {
-		motors[0] = 0.1; // idle thrust
-		motors[1] = 0.1;
-		motors[2] = 0.1;
-		motors[3] = 0.1;
 		return;
 	}
 
@@ -149,29 +148,15 @@ void controlTorque() {
 	motors[MOTOR_REAR_LEFT] = thrustTarget + torqueTarget.x + torqueTarget.y - torqueTarget.z;
 	motors[MOTOR_REAR_RIGHT] = thrustTarget - torqueTarget.x + torqueTarget.y + torqueTarget.z;
 
-	// Prioritize angle control over thrust control
-	desaturate(motors[MOTOR_FRONT_LEFT], motors[MOTOR_FRONT_RIGHT], motors[MOTOR_REAR_LEFT], motors[MOTOR_REAR_RIGHT]);
-
 	motors[0] = constrain(motors[0], 0, 1);
 	motors[1] = constrain(motors[1], 0, 1);
 	motors[2] = constrain(motors[2], 0, 1);
 	motors[3] = constrain(motors[3], 0, 1);
 }
 
-void desaturate(float& a, float& b, float& c, float& d) {
-	float maxThrust = max(max(a, b), max(c, d));
-	if (maxThrust > 1) {
-		float diff = maxThrust - 1;
-		a -= diff;
-		b -= diff;
-		c -= diff;
-		d -= diff;
-	}
-}
-
 const char* getModeName() {
 	switch (mode) {
-		case RAW: return "RAW";
+		case MANUAL: return "MANUAL";
 		case ACRO: return "ACRO";
 		case STAB: return "STAB";
 		case AUTO: return "AUTO";

flix/estimate.ino

@@ -1,25 +1,21 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 
-// Attitude estimation using gyro and accelerometer
+// Attitude estimation from gyro and accelerometer
 
 #include "quaternion.h"
 #include "vector.h"
 #include "lpf.h"
 #include "util.h"
 
-Vector rates; // estimated angular rates, rad/s
+#define WEIGHT_ACC 0.003
-Quaternion attitude; // estimated attitude
+#define RATES_LFP_ALPHA 0.2 // cutoff frequency ~ 40 Hz
-bool landed;
 
-float accWeight = 0.003;
+LowPassFilter<Vector> ratesFilter(RATES_LFP_ALPHA);
-float levelWeight = 0.0002;
-LowPassFilter<Vector> ratesFilter(0.2); // cutoff frequency ~ 40 Hz
 
 void estimate() {
 	applyGyro();
 	applyAcc();
-	applyLevel();
 }
 
 void applyGyro() {
@@ -32,24 +28,15 @@ void applyGyro() {
 
 void applyAcc() {
 	// test should we apply accelerometer gravity correction
-	landed = !motorsActive() && abs(acc.norm() - ONE_G) < ONE_G * 0.1f;
+	float accNorm = acc.norm();
+	landed = !motorsActive() && abs(accNorm - ONE_G) < ONE_G * 0.1f;
 
 	if (!landed) return;
 
 	// calculate accelerometer correction
 	Vector up = Quaternion::rotateVector(Vector(0, 0, 1), attitude);
-	Vector correction = Vector::rotationVectorBetween(acc, up) * accWeight;
+	Vector correction = Vector::rotationVectorBetween(acc, up) * WEIGHT_ACC;
 
 	// apply correction
 	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(correction));
 }
-
-void applyLevel() {
-	if (landed) return;
-	if (thrustTarget < 0.1) return; // skip at idle thrust
-
-	// assume the pilot keeps the drone more or less level in flight
-	Vector up = Quaternion::rotateVector(Vector(0, 0, 1), attitude);
-	Vector correction = Vector::rotationVectorBetween(Vector(0, 0, 1), up) * levelWeight;
-	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(correction));
-}

flix/failsafe.ino

@@ -3,11 +3,11 @@
 
 // Fail-safe functions
 
-extern float controlTime;
+#define RC_LOSS_TIMEOUT 0.2
-extern float controlRoll, controlPitch, controlThrottle, controlYaw;
+#define DESCEND_TIME 3.0 // time to descend from full throttle to zero
 
-float rcLossTimeout = 1;
+extern double controlTime;
-float descendTime = 10;
+extern float controlRoll, controlPitch, controlThrottle, controlYaw;
 
 void failsafe() {
 	rcLossFailsafe();
@@ -16,32 +16,34 @@ void failsafe() {
 
 // RC loss failsafe
 void rcLossFailsafe() {
+	if (mode == AUTO) return;
 	if (!armed) return;
-	if (t - controlTime > rcLossTimeout) {
+	if (t - controlTime > RC_LOSS_TIMEOUT) {
 		descend();
 	}
 }
 
-// Smooth descend on RC lost
-void descend() {
-	mode = AUTO;
-	attitudeTarget = Quaternion();
-	thrustTarget -= dt / descendTime;
-	if (thrustTarget < 0) {
-		thrustTarget = 0;
-		armed = false;
-	}
-}
-
 // Allow pilot to interrupt automatic flight
 void autoFailsafe() {
 	static float roll, pitch, yaw, throttle;
+
 	if (roll != controlRoll || pitch != controlPitch || yaw != controlYaw || abs(throttle - controlThrottle) > 0.05) {
-		// controls changed and mode switch is not configured
+		if (mode == AUTO && !isfinite(controlMode)) {
-		if (mode == AUTO && invalid(controlMode)) mode = STAB; // regain control by the pilot
+			print("Failsafe: regain control to pilot\n");
+			mode = STAB; // regain control to the pilot
 		}
+	}
+
 	roll = controlRoll;
 	pitch = controlPitch;
 	yaw = controlYaw;
 	throttle = controlThrottle;
 }
+
+// Smooth descend on RC lost
+void descend() {
+	mode = AUTO;
+	thrustTarget -= dt / DESCEND_TIME;
+	if (thrustTarget < 0) thrustTarget = 0;
+	if (thrustTarget == 0) armed = false;
+}

flix/flix.ino

@@ -7,23 +7,31 @@
 #include "quaternion.h"
 #include "util.h"
 
-extern float t, dt;
+#define SERIAL_BAUDRATE 115200
-extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
+#define WIFI_ENABLED 1
-extern Vector gyro, acc;
+
-extern Vector rates;
+double t = NAN; // current step time, s
-extern Quaternion attitude;
+float dt; // time delta from previous step, s
-extern bool landed;
+float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
-extern float motors[4];
+float controlArmed = NAN, controlMode = NAN;
+Vector gyro; // gyroscope data
+Vector acc; // accelerometer data, m/s/s
+Vector rates; // filtered angular rates, rad/s
+Quaternion attitude; // estimated attitude
+bool landed; // are we landed and stationary
+float motors[4]; // normalized motors thrust in range [0..1]
 
 void setup() {
-	Serial.begin(115200);
+	Serial.begin(SERIAL_BAUDRATE);
 	print("Initializing flix\n");
+	disableBrownOut();
 	setupParameters();
-	setupPower();
 	setupLED();
-	setLED(true);
 	setupMotors();
+	setLED(true);
+#if WIFI_ENABLED
 	setupWiFi();
+#endif
 	setupIMU();
 	setupRC();
 	setLED(false);
@@ -38,8 +46,9 @@ void loop() {
 	control();
 	sendMotors();
 	handleInput();
+#if WIFI_ENABLED
 	processMavlink();
-	readVoltage();
+#endif
 	logData();
 	syncParameters();
 }

flix/imu.ino

@@ -4,63 +4,62 @@
 // Work with the IMU sensor
 
 #include <SPI.h>
-#include <FlixPeriph.h>
+#include <MPU9250.h>
-#include "vector.h"
 #include "lpf.h"
 #include "util.h"
 
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
-Vector imuRotation(0, 0, PI / 2); // imu orientation as Euler angles
 
-Vector gyro; // gyroscope output, rad/s
-Vector gyroBias;
-
-Vector acc; // accelerometer output, m/s/s
 Vector accBias;
 Vector accScale(1, 1, 1);
-
+Vector gyroBias;
-LowPassFilter<Vector> gyroBiasFilter(0.001);
 
 void setupIMU() {
 	print("Setup IMU\n");
-	imu.begin();
+	IMU.begin();
 	configureIMU();
 }
 
 void configureIMU() {
-	imu.setAccelRange(imu.ACCEL_RANGE_4G);
+	IMU.setAccelRange(IMU.ACCEL_RANGE_4G);
-	imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
+	IMU.setGyroRange(IMU.GYRO_RANGE_2000DPS);
-	imu.setDLPF(imu.DLPF_MAX);
+	IMU.setDLPF(IMU.DLPF_MAX);
-	imu.setRate(imu.RATE_1KHZ_APPROX);
+	IMU.setRate(IMU.RATE_1KHZ_APPROX);
-	imu.setupInterrupt();
+	IMU.setupInterrupt();
 }
 
 void readIMU() {
-	imu.waitForData();
+	IMU.waitForData();
-	imu.getGyro(gyro.x, gyro.y, gyro.z);
+	IMU.getGyro(gyro.x, gyro.y, gyro.z);
-	imu.getAccel(acc.x, acc.y, acc.z);
+	IMU.getAccel(acc.x, acc.y, acc.z);
 	calibrateGyroOnce();
-
+	// apply scale and bias
-	// Apply scale and bias
 	acc = (acc - accBias) / accScale;
 	gyro = gyro - gyroBias;
+	// rotate
+	rotateIMU(acc);
+	rotateIMU(gyro);
+}
 
-	// Rotate to body frame
+void rotateIMU(Vector& data) {
-	Quaternion rotation = Quaternion::fromEuler(imuRotation);
+	// Rotate from LFD to FLU
-	acc = Quaternion::rotateVector(acc, rotation.inversed());
+	// NOTE: In case of using other IMU orientation, change this line:
-	gyro = Quaternion::rotateVector(gyro, rotation.inversed());
+	data = Vector(data.y, data.x, -data.z);
+	// Axes orientation for various boards: https://github.com/okalachev/flixperiph#imu-axes-orientation
 }
 
 void calibrateGyroOnce() {
-	static Delay landedDelay(2);
+	static float landedTime = 0;
-	if (!landedDelay.update(landed)) return; // calibrate only if definitely stationary
+	landedTime = landed ? landedTime + dt : 0;
+	if (landedTime < 2) return; // calibrate only if definitely stationary
 
-	gyroBias = gyroBiasFilter.update(gyro);
+	static LowPassFilter<Vector> gyroCalibrationFilter(0.001);
+	gyroBias = gyroCalibrationFilter.update(gyro);
 }
 
 void calibrateAccel() {
 	print("Calibrating accelerometer\n");
-	imu.setAccelRange(imu.ACCEL_RANGE_2G); // the most sensitive mode
+	IMU.setAccelRange(IMU.ACCEL_RANGE_2G); // the most sensitive mode
 
 	print("1/6 Place level [8 sec]\n");
 	pause(8);
@@ -94,9 +93,9 @@ void calibrateAccelOnce() {
 	// Compute the average of the accelerometer readings
 	acc = Vector(0, 0, 0);
 	for (int i = 0; i < samples; i++) {
-		imu.waitForData();
+		IMU.waitForData();
 		Vector sample;
-		imu.getAccel(sample.x, sample.y, sample.z);
+		IMU.getAccel(sample.x, sample.y, sample.z);
 		acc = acc + sample;
 	}
 	acc = acc / samples;
@@ -108,7 +107,6 @@ void calibrateAccelOnce() {
 	if (acc.x < accMin.x) accMin.x = acc.x;
 	if (acc.y < accMin.y) accMin.y = acc.y;
 	if (acc.z < accMin.z) accMin.z = acc.z;
-
 	// Compute scale and bias
 	accScale = (accMax - accMin) / 2 / ONE_G;
 	accBias = (accMax + accMin) / 2;
@@ -121,17 +119,7 @@ void printIMUCalibration() {
 }
 
 void printIMUInfo() {
-	imu.status() ? print("status: ERROR %d\n", imu.status()) : print("status: OK\n");
+	IMU.status() ? print("status: ERROR %d\n", IMU.status()) : print("status: OK\n");
-	print("model: %s\n", imu.getModel());
+	print("model: %s\n", IMU.getModel());
-	print("who am I: 0x%02X\n", imu.whoAmI());
+	print("who am I: 0x%02X\n", IMU.whoAmI());
-	print("rate: %.0f\n", loopRate);
-	print("temperature: %.1f °C\n", imu.getTemp());
-	print("gyro: %f %f %f\n", gyro.x, gyro.y, gyro.z);
-	print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
-	imu.waitForData();
-	Vector rawGyro, rawAcc;
-	imu.getGyro(rawGyro.x, rawGyro.y, rawGyro.z);
-	imu.getAccel(rawAcc.x, rawAcc.y, rawAcc.z);
-	print("raw gyro: %f %f %f\n", rawGyro.x, rawGyro.y, rawGyro.z);
-	print("raw acc: %f %f %f\n", rawAcc.x, rawAcc.y, rawAcc.z);
 }

flix/log.ino

@@ -4,12 +4,13 @@
 // In-RAM logging
 
 #include "vector.h"
-#include "util.h"
 
 #define LOG_RATE 100
 #define LOG_DURATION 10
+#define LOG_PERIOD 1.0 / LOG_RATE
 #define LOG_SIZE LOG_DURATION * LOG_RATE
 
+float tFloat;
 Vector attitudeEuler;
 Vector attitudeTargetEuler;
 
@@ -19,7 +20,7 @@ struct LogEntry {
 };
 
 LogEntry logEntries[] = {
-	{"t", &t},
+	{"t", &tFloat},
 	{"rates.x", &rates.x},
 	{"rates.y", &rates.y},
 	{"rates.z", &rates.z},
@@ -39,6 +40,7 @@ const int logColumns = sizeof(logEntries) / sizeof(logEntries[0]);
 float logBuffer[LOG_SIZE][logColumns];
 
 void prepareLogData() {
+	tFloat = t;
 	attitudeEuler = attitude.toEuler();
 	attitudeTargetEuler = attitudeTarget.toEuler();
 }
@@ -46,8 +48,9 @@ void prepareLogData() {
 void logData() {
 	if (!armed) return;
 	static int logPointer = 0;
-	static Rate period(LOG_RATE);
+	static double logTime = 0;
-	if (!period) return;
+	if (t - logTime < LOG_PERIOD) return;
+	logTime = t;
 
 	prepareLogData();
 
@@ -61,13 +64,12 @@ void logData() {
 	}
 }
 
-void printLogHeader() {
+void dumpLog() {
+	// Print header
 	for (int i = 0; i < logColumns; i++) {
 		print("%s%s", logEntries[i].name, i < logColumns - 1 ? "," : "\n");
 	}
-}
+	// Print data
-
-void printLogData() {
 	for (int i = 0; i < LOG_SIZE; i++) {
 		if (logBuffer[i][0] == 0) continue; // skip empty records
 		for (int j = 0; j < logColumns; j++) {

flix/lpf.h

@@ -14,10 +14,15 @@ public:
 	LowPassFilter(float alpha): alpha(alpha) {};
 
 	T update(const T input) {
-		if (!init) {
+		if (alpha == 1) { // filter disabled
-			init = true;
+			return input;
-			return output = input;
 		}
+
+		if (!initialized) {
+			output = input;
+			initialized = true;
+		}
+
 		return output += alpha * (input - output);
 	}
 
@@ -26,9 +31,9 @@ public:
 	}
 
 	void reset() {
-		init = false;
+		initialized = false;
 	}
 
 private:
-	bool init = false;
+	bool initialized = false;
 };

flix/mavlink.ino

@@ -3,23 +3,21 @@
 
 // MAVLink communication
 
+#if WIFI_ENABLED
+
 #include <MAVLink.h>
-#include "util.h"
 
-extern float controlTime;
+#define SYSTEM_ID 1
-extern float voltage;
+#define PERIOD_SLOW 1.0
+#define PERIOD_FAST 0.1
+#define MAVLINK_CONTROL_YAW_DEAD_ZONE 0.1f
 
-int mavlinkSysId = 1;
+float mavlinkControlScale = 0.7;
-
-Rate telemetrySlow(2);
-Rate telemetryAttitude(20);
-Rate telemetryRC(10);
-Rate telemetryMotors(10);
-Rate telemetryIMU(15);
-
-bool mavlinkConnected = false;
 String mavlinkPrintBuffer;
 
+extern double controlTime;
+extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlArmed, controlMode;
+
 void processMavlink() {
 	sendMavlink();
 	receiveMavlink();
@@ -28,58 +26,46 @@ void processMavlink() {
 void sendMavlink() {
 	sendMavlinkPrint();
 
+	static double lastSlow = 0;
+	static double lastFast = 0;
+
 	mavlink_message_t msg;
 	uint32_t time = t * 1000;
 
-	if (telemetrySlow) {
+	if (t - lastSlow >= PERIOD_SLOW) {
-		mavlink_msg_heartbeat_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
+		lastSlow = t;
-			(armed ? MAV_MODE_FLAG_SAFETY_ARMED : 0) |
+
-			((mode == STAB) ? MAV_MODE_FLAG_STABILIZE_ENABLED : 0) |
+		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
+			(armed * MAV_MODE_FLAG_SAFETY_ARMED) |
+			(mode == STAB) * MAV_MODE_FLAG_STABILIZE_ENABLED |
 			((mode == AUTO) ? MAV_MODE_FLAG_AUTO_ENABLED : MAV_MODE_FLAG_MANUAL_INPUT_ENABLED),
 			mode, MAV_STATE_STANDBY);
 		sendMessage(&msg);
-	}
 
-	if (!mavlinkConnected) return; // send only heartbeat until connected
+		mavlink_msg_extended_sys_state_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
-
-	if (telemetrySlow) {
-		mavlink_msg_extended_sys_state_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
 			MAV_VTOL_STATE_UNDEFINED, landed ? MAV_LANDED_STATE_ON_GROUND : MAV_LANDED_STATE_IN_AIR);
 		sendMessage(&msg);
 	}
 
-	if (telemetrySlow && valid(voltage)) {
+	if (t - lastFast >= PERIOD_FAST) {
-		uint16_t voltages[] = {(uint16_t)(voltage * 1000), UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX};
+		lastFast = t;
-		uint16_t voltagesExt[] = {0, 0, 0, 0};
-		float remaining = constrain(mapf(voltage, 3.4, 4.2, 0, 1), 0, 1);
-		mavlink_msg_battery_status_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, MAV_BATTERY_FUNCTION_ALL,
-			MAV_BATTERY_TYPE_LIPO, INT16_MAX, voltages, -1, -1, -1, remaining * 100, 0, MAV_BATTERY_CHARGE_STATE_OK, voltagesExt, 0, 0);
-		sendMessage(&msg);
-	}
 
-	if (telemetryAttitude) {
+		const float zeroQuat[] = {0, 0, 0, 0};
-		const float offset[] = {0, 0, 0, 0};
+		mavlink_msg_attitude_quaternion_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
-		mavlink_msg_attitude_quaternion_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, zeroQuat); // convert to frd
-			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, offset); // convert to frd
 		sendMessage(&msg);
-	}
 
-	if (telemetryRC && channels[0]) { // 0 means no RC input
+		mavlink_msg_rc_channels_raw_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, controlTime * 1000, 0,
-		mavlink_msg_rc_channels_raw_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, controlTime * 1000, 0,
 			channels[0], channels[1], channels[2], channels[3], channels[4], channels[5], channels[6], channels[7], UINT8_MAX);
-		sendMessage(&msg);
+		if (channels[0] != 0) sendMessage(&msg); // 0 means no RC input
-	}
 
-	if (telemetryMotors) {
 		float controls[8];
 		memcpy(controls, motors, sizeof(motors));
-		mavlink_msg_actuator_control_target_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time, 0, controls);
+		mavlink_msg_actuator_control_target_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time, 0, controls);
 		sendMessage(&msg);
-	}
 
-	if (telemetryIMU) {
+		mavlink_msg_scaled_imu_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time,
-		mavlink_msg_scaled_imu_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time,
+			acc.x * 1000, -acc.y * 1000, -acc.z * 1000, // convert to frd
-			acc.x / ONE_G * 1000, -acc.y / ONE_G * 1000, -acc.z / ONE_G * 1000, // convert to frd
 			gyro.x * 1000, -gyro.y * 1000, -gyro.z * 1000,
 			0, 0, 0, 0);
 		sendMessage(&msg);
@@ -101,7 +87,6 @@ void receiveMavlink() {
 	mavlink_status_t status;
 	for (int i = 0; i < len; i++) {
 		if (mavlink_parse_char(MAVLINK_COMM_0, buf[i], &msg, &status)) {
-			mavlinkConnected = true;
 			handleMavlink(&msg);
 		}
 	}
@@ -113,24 +98,27 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_MANUAL_CONTROL) {
 		mavlink_manual_control_t m;
 		mavlink_msg_manual_control_decode(&msg, &m);
-		if (m.target && m.target != mavlinkSysId) return; // 0 is broadcast
+		if (m.target && m.target != SYSTEM_ID) return; // 0 is broadcast
 
 		controlThrottle = m.z / 1000.0f;
-		controlPitch = m.x / 1000.0f;
+		controlPitch = m.x / 1000.0f * mavlinkControlScale;
-		controlRoll = m.y / 1000.0f;
+		controlRoll = m.y / 1000.0f * mavlinkControlScale;
-		controlYaw = m.r / 1000.0f;
+		controlYaw = m.r / 1000.0f * mavlinkControlScale;
-		controlMode = NAN;
+		controlMode = NAN; // keep mode
+		controlArmed = NAN;
 		controlTime = t;
+
+		if (abs(controlYaw) < MAVLINK_CONTROL_YAW_DEAD_ZONE) controlYaw = 0;
 	}
 
 	if (msg.msgid == MAVLINK_MSG_ID_PARAM_REQUEST_LIST) {
 		mavlink_param_request_list_t m;
 		mavlink_msg_param_request_list_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
 		mavlink_message_t msg;
 		for (int i = 0; i < parametersCount(); i++) {
-			mavlink_msg_param_value_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+			mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 				getParameterName(i), getParameter(i), MAV_PARAM_TYPE_REAL32, parametersCount(), i);
 			sendMessage(&msg);
 		}
@@ -139,7 +127,7 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_PARAM_REQUEST_READ) {
 		mavlink_param_request_read_t m;
 		mavlink_msg_param_request_read_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
 		char name[MAVLINK_MSG_PARAM_REQUEST_READ_FIELD_PARAM_ID_LEN + 1];
 		strlcpy(name, m.param_id, sizeof(name)); // param_id might be not null-terminated
@@ -148,7 +136,7 @@ void handleMavlink(const void *_msg) {
 			memcpy(name, getParameterName(m.param_index), 16);
 		}
 		mavlink_message_t msg;
-		mavlink_msg_param_value_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			name, value, MAV_PARAM_TYPE_REAL32, parametersCount(), m.param_index);
 		sendMessage(&msg);
 	}
@@ -156,33 +144,32 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_PARAM_SET) {
 		mavlink_param_set_t m;
 		mavlink_msg_param_set_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
 		char name[MAVLINK_MSG_PARAM_SET_FIELD_PARAM_ID_LEN + 1];
 		strlcpy(name, m.param_id, sizeof(name)); // param_id might be not null-terminated
-		bool success = setParameter(name, m.param_value);
+		setParameter(name, m.param_value);
-		if (!success) return;
 		// send ack
 		mavlink_message_t msg;
-		mavlink_msg_param_value_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
-			m.param_id, getParameter(name), MAV_PARAM_TYPE_REAL32, parametersCount(), 0); // index is unknown
+			m.param_id, m.param_value, MAV_PARAM_TYPE_REAL32, parametersCount(), 0); // index is unknown
 		sendMessage(&msg);
 	}
 
 	if (msg.msgid == MAVLINK_MSG_ID_MISSION_REQUEST_LIST) { // handle to make qgc happy
 		mavlink_mission_request_list_t m;
 		mavlink_msg_mission_request_list_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
 		mavlink_message_t msg;
-		mavlink_msg_mission_count_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, 0, 0, MAV_MISSION_TYPE_MISSION, 0);
+		mavlink_msg_mission_count_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, 0, 0, 0, MAV_MISSION_TYPE_MISSION, 0);
 		sendMessage(&msg);
 	}
 
 	if (msg.msgid == MAVLINK_MSG_ID_SERIAL_CONTROL) {
 		mavlink_serial_control_t m;
 		mavlink_msg_serial_control_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
 		char data[MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN + 1];
 		strlcpy(data, (const char *)m.data, m.count); // data might be not null-terminated
@@ -194,7 +181,7 @@ void handleMavlink(const void *_msg) {
 
 		mavlink_set_attitude_target_t m;
 		mavlink_msg_set_attitude_target_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
 		// copy attitude, rates and thrust targets
 		ratesTarget.x = m.body_roll_rate;
@@ -208,6 +195,7 @@ void handleMavlink(const void *_msg) {
 		ratesExtra = Vector(0, 0, 0);
 
 		if (m.type_mask & ATTITUDE_TARGET_TYPEMASK_ATTITUDE_IGNORE) attitudeTarget.invalidate();
+
 		armed = m.thrust > 0;
 	}
 
@@ -216,61 +204,34 @@ void handleMavlink(const void *_msg) {
 
 		mavlink_set_actuator_control_target_t m;
 		mavlink_msg_set_actuator_control_target_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 
-		attitudeTarget.invalidate();
-		ratesTarget.invalidate();
-		torqueTarget.invalidate();
 		memcpy(motors, m.controls, sizeof(motors)); // copy motor thrusts
-		armed = motors[0] > 0 || motors[1] > 0 || motors[2] > 0 || motors[3] > 0;
-	}
-
-	if (msg.msgid == MAVLINK_MSG_ID_LOG_REQUEST_DATA) {
-		mavlink_log_request_data_t m;
-		mavlink_msg_log_request_data_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
-
-		// Send all log records
-		for (int i = 0; i < sizeof(logBuffer) / sizeof(logBuffer[0]); i++) {
-			mavlink_message_t msg;
-			mavlink_msg_log_data_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, i,
-				sizeof(logBuffer[0]), (uint8_t *)logBuffer[i]);
-			sendMessage(&msg);
-		}
 	}
 
 	// Handle commands
 	if (msg.msgid == MAVLINK_MSG_ID_COMMAND_LONG) {
 		mavlink_command_long_t m;
 		mavlink_msg_command_long_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
+		mavlink_message_t ack;
 		mavlink_message_t response;
-		bool accepted = false;
 
 		if (m.command == MAV_CMD_REQUEST_MESSAGE && m.param1 == MAVLINK_MSG_ID_AUTOPILOT_VERSION) {
-			accepted = true;
+			mavlink_msg_command_ack_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, MAV_RESULT_ACCEPTED, UINT8_MAX, 0, msg.sysid, msg.compid);
-			mavlink_msg_autopilot_version_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &response,
+			sendMessage(&ack);
+			mavlink_msg_autopilot_version_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &response,
 				MAV_PROTOCOL_CAPABILITY_PARAM_FLOAT | MAV_PROTOCOL_CAPABILITY_MAVLINK2, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0);
 			sendMessage(&response);
 		}
 
-		if (m.command == MAV_CMD_COMPONENT_ARM_DISARM) {
-			if (m.param1 == 1 && controlThrottle > 0.05) return; // don't arm if throttle is not low
-			accepted = true;
-			armed = m.param1 == 1;
-		}
-
 		if (m.command == MAV_CMD_DO_SET_MODE) {
-			if (m.param2 < 0 || m.param2 > AUTO) return; // incorrect mode
+			if (!(m.param2 >= 0 && m.param2 <= AUTO)) return;
-			accepted = true;
+			mode = static_cast<decltype(mode)>(m.param2);
-			mode = m.param2;
+			mavlink_msg_command_ack_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, MAV_RESULT_ACCEPTED, UINT8_MAX, 0, msg.sysid, msg.compid);
-		}
-
-		// send command ack
-		mavlink_message_t ack;
-		mavlink_msg_command_ack_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, accepted ? MAV_RESULT_ACCEPTED : MAV_RESULT_UNSUPPORTED, UINT8_MAX, 0, msg.sysid, msg.compid);
 			sendMessage(&ack);
 		}
+	}
 }
 
 // Send shell output to GCS
@@ -285,7 +246,7 @@ void sendMavlinkPrint() {
 		char data[MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN + 1];
 		strlcpy(data, str + i, sizeof(data));
 		mavlink_message_t msg;
-		mavlink_msg_serial_control_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_serial_control_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			SERIAL_CONTROL_DEV_SHELL,
 			i + MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN < strlen(str) ? SERIAL_CONTROL_FLAG_MULTI : 0, // more chunks to go
 			0, 0, strlen(data), (uint8_t *)data, 0, 0);
@@ -293,3 +254,5 @@ void sendMavlinkPrint() {
 	}
 	mavlinkPrintBuffer.clear();
 }
+
+#endif

flix/motors.ino

@@ -1,51 +1,54 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 
-// PWM control for motors
+// Motors output control using MOSFETs
+// In case of using ESCs, change PWM_STOP, PWM_MIN and PWM_MAX to appropriate values in μs, decrease PWM_FREQUENCY (to 400)
 
 #include "util.h"
 
-float motors[4]; // normalized motor thrusts in range [0..1]
+#define MOTOR_0_PIN 12 // rear left
+#define MOTOR_1_PIN 13 // rear right
+#define MOTOR_2_PIN 14 // front right
+#define MOTOR_3_PIN 15 // front left
 
-int motorPins[4] = {12, 13, 14, 15}; // default pin numbers
+#define PWM_FREQUENCY 78000
-int pwmFrequency = 78000;
+#define PWM_RESOLUTION 10
-int pwmResolution = 10;
+#define PWM_STOP 0
-int pwmStop = 0;
+#define PWM_MIN 0
-int pwmMin = 0;
+#define PWM_MAX 1000000 / PWM_FREQUENCY
-int pwmMax = -1; // -1 means duty cycle mode
 
-const int MOTOR_REAR_LEFT = 0, MOTOR_REAR_RIGHT = 1, MOTOR_FRONT_RIGHT = 2, MOTOR_FRONT_LEFT = 3;
+// Motors array indexes:
+const int MOTOR_REAR_LEFT = 0;
+const int MOTOR_REAR_RIGHT = 1;
+const int MOTOR_FRONT_RIGHT = 2;
+const int MOTOR_FRONT_LEFT = 3;
 
 void setupMotors() {
 	print("Setup Motors\n");
-	// Configure pins
+
-	for (int i = 0; i < 4; i++) {
+	// configure pins
-		if (motorPins[i] < 0) continue; // skip unassigned motors
+	ledcAttach(MOTOR_0_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
-		ledcAttach(motorPins[i], pwmFrequency, pwmResolution);
+	ledcAttach(MOTOR_1_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
-		pwmFrequency = ledcChangeFrequency(motorPins[i], pwmFrequency, pwmResolution); // when reconfiguring
+	ledcAttach(MOTOR_2_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
-	}
+	ledcAttach(MOTOR_3_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
+
 	sendMotors();
 	print("Motors initialized\n");
 }
 
-void sendMotors() {
-	for (int i = 0; i < 4; i++) {
-		if (motorPins[i] < 0) continue; // skip unassigned motors
-		ledcWrite(motorPins[i], getDutyCycle(motors[i]));
-	}
-}
-
 int getDutyCycle(float value) {
 	value = constrain(value, 0, 1);
-
+	float pwm = mapff(value, 0, 1, PWM_MIN, PWM_MAX);
-	if (pwmMax >= 0) { // pwm mode
+	if (value == 0) pwm = PWM_STOP;
-		float pwm = mapf(value, 0, 1, pwmMin, pwmMax);
+	float duty = mapff(pwm, 0, 1000000 / PWM_FREQUENCY, 0, (1 << PWM_RESOLUTION) - 1);
-		if (value == 0) pwm = pwmStop;
-		float duty = mapf(pwm, 0, 1000000 / pwmFrequency, 0, (1 << pwmResolution) - 1);
 	return round(duty);
-	} else { // duty cycle mode
+}
-		return round(value * ((1 << pwmResolution) - 1));
+
-	}
+void sendMotors() {
+	ledcWrite(MOTOR_0_PIN, getDutyCycle(motors[0]));
+	ledcWrite(MOTOR_1_PIN, getDutyCycle(motors[1]));
+	ledcWrite(MOTOR_2_PIN, getDutyCycle(motors[2]));
+	ledcWrite(MOTOR_3_PIN, getDutyCycle(motors[3]));
 }
 
 bool motorsActive() {
@@ -54,7 +57,7 @@ bool motorsActive() {
 
 void testMotor(int n) {
 	print("Testing motor %d\n", n);
-	motors[n] = 0.2;
+	motors[n] = 1;
 	delay(50); // ESP32 may need to wait until the end of the current cycle to change duty https://github.com/espressif/arduino-esp32/issues/5306
 	sendMotors();
 	pause(3);

flix/parameters.ino

@@ -4,88 +4,52 @@
 // Parameters storage in flash memory
 
 #include <Preferences.h>
-#include "util.h"
 
-extern int channelZero[16], channelMax[16];
+extern float channelZero[16];
-extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
+extern float channelMax[16];
-extern int rcRxPin, voltagePin;
+extern float rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
-extern int wifiMode, wifiLongRange, udpLocalPort, udpRemotePort, espnowChannel;
+extern float mavlinkControlScale;
-extern float rcLossTimeout, descendTime;
-extern float voltageScale;
-extern LowPassFilter<float> voltageFilter;
 
 Preferences storage;
 
 struct Parameter {
-	const char *name; // max length is 15
+	const char *name; // max length is 16
-	bool integer;
+	float *variable;
-	union { float *f; int *i; }; // pointer to the variable
+	float value; // cache
-	float inital; // default value
-	float cache; // what's stored in flash
-	void (*callback)(); // called after parameter change
-	Parameter(const char *name, float *variable, void (*callback)() = nullptr) : name(name), integer(false), f(variable), callback(callback) {};
-	Parameter(const char *name, int *variable, void (*callback)() = nullptr) : name(name), integer(true), i(variable), callback(callback) {};
-	float getValue() const { return integer ? *i : *f; };
-	void setValue(const float value) { if (integer) *i = value; else *f = value; };
 };
 
 Parameter parameters[] = {
 	// control
-	{"CTL_R_RATE_P", &rollRatePID.p},
+	{"ROLLRATE_P", &rollRatePID.p},
-	{"CTL_R_RATE_I", &rollRatePID.i},
+	{"ROLLRATE_I", &rollRatePID.i},
-	{"CTL_R_RATE_D", &rollRatePID.d},
+	{"ROLLRATE_D", &rollRatePID.d},
-	{"CTL_R_RATE_WU", &rollRatePID.windup},
+	{"ROLLRATE_I_LIM", &rollRatePID.windup},
-	{"CTL_R_RATE_D_A", &rollRatePID.lpf.alpha},
+	{"PITCHRATE_P", &pitchRatePID.p},
-	{"CTL_P_RATE_P", &pitchRatePID.p},
+	{"PITCHRATE_I", &pitchRatePID.i},
-	{"CTL_P_RATE_I", &pitchRatePID.i},
+	{"PITCHRATE_D", &pitchRatePID.d},
-	{"CTL_P_RATE_D", &pitchRatePID.d},
+	{"PITCHRATE_I_LIM", &pitchRatePID.windup},
-	{"CTL_P_RATE_WU", &pitchRatePID.windup},
+	{"YAWRATE_P", &yawRatePID.p},
-	{"CTL_P_RATE_D_A", &pitchRatePID.lpf.alpha},
+	{"YAWRATE_I", &yawRatePID.i},
-	{"CTL_Y_RATE_P", &yawRatePID.p},
+	{"YAWRATE_D", &yawRatePID.d},
-	{"CTL_Y_RATE_I", &yawRatePID.i},
+	{"ROLL_P", &rollPID.p},
-	{"CTL_Y_RATE_D", &yawRatePID.d},
+	{"ROLL_I", &rollPID.i},
-	{"CTL_Y_RATE_D_A", &yawRatePID.lpf.alpha},
+	{"ROLL_D", &rollPID.d},
-	{"CTL_R_P", &rollPID.p},
+	{"PITCH_P", &pitchPID.p},
-	{"CTL_R_I", &rollPID.i},
+	{"PITCH_I", &pitchPID.i},
-	{"CTL_R_D", &rollPID.d},
+	{"PITCH_D", &pitchPID.d},
-	{"CTL_P_P", &pitchPID.p},
+	{"YAW_P", &yawPID.p},
-	{"CTL_P_I", &pitchPID.i},
+	{"PITCHRATE_MAX", &maxRate.y},
-	{"CTL_P_D", &pitchPID.d},
+	{"ROLLRATE_MAX", &maxRate.x},
-	{"CTL_Y_P", &yawPID.p},
+	{"YAWRATE_MAX", &maxRate.z},
-	{"CTL_P_RATE_MAX", &maxRate.y},
+	{"TILT_MAX", &tiltMax},
-	{"CTL_R_RATE_MAX", &maxRate.x},
-	{"CTL_Y_RATE_MAX", &maxRate.z},
-	{"CTL_TILT_MAX", &tiltMax},
-	{"CTL_FLT_MODE_0", &flightModes[0]},
-	{"CTL_FLT_MODE_1", &flightModes[1]},
-	{"CTL_FLT_MODE_2", &flightModes[2]},
 	// imu
-	{"IMU_ROT_ROLL", &imuRotation.x},
+	{"ACC_BIAS_X", &accBias.x},
-	{"IMU_ROT_PITCH", &imuRotation.y},
+	{"ACC_BIAS_Y", &accBias.y},
-	{"IMU_ROT_YAW", &imuRotation.z},
+	{"ACC_BIAS_Z", &accBias.z},
-	{"IMU_ACC_BIAS_X", &accBias.x},
+	{"ACC_SCALE_X", &accScale.x},
-	{"IMU_ACC_BIAS_Y", &accBias.y},
+	{"ACC_SCALE_Y", &accScale.y},
-	{"IMU_ACC_BIAS_Z", &accBias.z},
+	{"ACC_SCALE_Z", &accScale.z},
-	{"IMU_ACC_SCALE_X", &accScale.x},
-	{"IMU_ACC_SCALE_Y", &accScale.y},
-	{"IMU_ACC_SCALE_Z", &accScale.z},
-	{"IMU_GYRO_BIAS_A", &gyroBiasFilter.alpha},
-	// estimate
-	{"EST_ACC_WEIGHT", &accWeight},
-	{"EST_LVL_WEIGHT", &levelWeight},
-	{"EST_RATES_LPF_A", &ratesFilter.alpha},
-	// motors
-	{"MOT_PIN_FL", &motorPins[MOTOR_FRONT_LEFT], setupMotors},
-	{"MOT_PIN_FR", &motorPins[MOTOR_FRONT_RIGHT], setupMotors},
-	{"MOT_PIN_RL", &motorPins[MOTOR_REAR_LEFT], setupMotors},
-	{"MOT_PIN_RR", &motorPins[MOTOR_REAR_RIGHT], setupMotors},
-	{"MOT_PWM_FREQ", &pwmFrequency, setupMotors},
-	{"MOT_PWM_RES", &pwmResolution, setupMotors},
-	{"MOT_PWM_STOP", &pwmStop},
-	{"MOT_PWM_MIN", &pwmMin},
-	{"MOT_PWM_MAX", &pwmMax},
 	// rc
-	{"RC_RX_PIN", &rcRxPin, setupRC},
 	{"RC_ZERO_0", &channelZero[0]},
 	{"RC_ZERO_1", &channelZero[1]},
 	{"RC_ZERO_2", &channelZero[2]},
@@ -106,41 +70,23 @@ Parameter parameters[] = {
 	{"RC_PITCH", &pitchChannel},
 	{"RC_THROTTLE", &throttleChannel},
 	{"RC_YAW", &yawChannel},
+	{"RC_ARMED", &armedChannel},
 	{"RC_MODE", &modeChannel},
-	// wifi
+#if WIFI_ENABLED
-	{"WIFI_MODE", &wifiMode},
+	// MAVLink
-	{"WIFI_PORT_LOC", &udpLocalPort},
+	{"MAV_CTRL_SCALE", &mavlinkControlScale},
-	{"WIFI_PORT_REM", &udpRemotePort},
+#endif
-	{"WIFI_LONG_RANGE", &wifiLongRange},
-	// espnow
-	{"ESPNOW_CHANNEL", &espnowChannel},
-	// mavlink
-	{"MAV_SYS_ID", &mavlinkSysId},
-	{"MAV_RATE_SLOW", &telemetrySlow.rate},
-	{"MAV_RATE_ATT", &telemetryAttitude.rate},
-	{"MAV_RATE_RC", &telemetryRC.rate},
-	{"MAV_RATE_MOT", &telemetryMotors.rate},
-	{"MAV_RATE_IMU", &telemetryIMU.rate},
-	// power
-	{"PWR_VOLT_PIN", &voltagePin, setupPower},
-	{"PWR_VOLT_SCALE", &voltageScale},
-	{"PWR_VOLT_LPF_A", &voltageFilter.alpha},
-	// safety
-	{"SF_RC_LOSS_TIME", &rcLossTimeout},
-	{"SF_DESCEND_TIME", &descendTime},
 };
 
 void setupParameters() {
-	print("Setup parameters\n");
+	storage.begin("flix", false);
-	storage.begin("flix");
 	// Read parameters from storage
 	for (auto &parameter : parameters) {
 		if (!storage.isKey(parameter.name)) {
-			storage.putFloat(parameter.name, parameter.getValue()); // store default value
+			storage.putFloat(parameter.name, *parameter.variable);
 		}
-		parameter.inital = parameter.getValue();
+		*parameter.variable = storage.getFloat(parameter.name, *parameter.variable);
-		parameter.setValue(storage.getFloat(parameter.name, 0));
+		parameter.value = *parameter.variable;
-		parameter.cache = parameter.getValue();
 	}
 }
 
@@ -155,13 +101,13 @@ const char *getParameterName(int index) {
 
 float getParameter(int index) {
 	if (index < 0 || index >= parametersCount()) return NAN;
-	return parameters[index].getValue();
+	return *parameters[index].variable;
 }
 
 float getParameter(const char *name) {
 	for (auto &parameter : parameters) {
-		if (strcasecmp(parameter.name, name) == 0) {
+		if (strcmp(parameter.name, name) == 0) {
-			return parameter.getValue();
+			return *parameter.variable;
 		}
 	}
 	return NAN;
@@ -169,10 +115,8 @@ float getParameter(const char *name) {
 
 bool setParameter(const char *name, const float value) {
 	for (auto &parameter : parameters) {
-		if (strcasecmp(parameter.name, name) == 0) {
+		if (strcmp(parameter.name, name) == 0) {
-			if (parameter.integer && !isfinite(value)) return false; // can't set integer to NaN or Inf
+			*parameter.variable = value;
-			parameter.setValue(value);
-			if (parameter.callback) parameter.callback();
 			return true;
 		}
 	}
@@ -180,28 +124,22 @@ bool setParameter(const char *name, const float value) {
 }
 
 void syncParameters() {
-	static Rate rate(1);
+	static double lastSync = 0;
-	if (!rate) return; // sync once per second
+	if (t - lastSync < 1) return; // sync once per second
 	if (motorsActive()) return; // don't use flash while flying, it may cause a delay
+	lastSync = t;
 
 	for (auto &parameter : parameters) {
-		if (floatEquals(parameter.getValue(), parameter.cache)) continue; // no change
+		if (parameter.value == *parameter.variable) continue;
-
+		if (isnan(parameter.value) && isnan(*parameter.variable)) continue; // handle NAN != NAN
-		storage.putFloat(parameter.name, parameter.getValue());
+		storage.putFloat(parameter.name, *parameter.variable);
-		parameter.cache = parameter.getValue(); // update cache
+		parameter.value = *parameter.variable;
 	}
 }
 
-void printParameters(const char *filter) {
+void printParameters() {
-	print("Name             Value          [Default]\n");
 	for (auto &parameter : parameters) {
-		if (strncasecmp(parameter.name, filter, strlen(filter))) continue;
+		print("%s = %g\n", parameter.name, *parameter.variable);
-
-		if (floatEquals(parameter.getValue(), parameter.inital)) { // parameter changed
-			print("%-15s  %-13g\n", parameter.name, parameter.getValue());
-		} else {
-			print("%-15s  %-13g  [%g]\n", parameter.name, parameter.getValue(), parameter.inital);
-		}
 	}
 }
 

flix/pid.h

@@ -9,44 +9,40 @@
 
 class PID {
 public:
-	float p, i, d;
+	float p = 0;
-	float windup;
+	float i = 0;
-	float dtMax;
+	float d = 0;
+	float windup = 0;
 
 	float derivative = 0;
 	float integral = 0;
 
 	LowPassFilter<float> lpf; // low pass filter for derivative term
 
-	PID(float p, float i, float d, float windup = 0, float dAlpha = 1, float dtMax = 0.1) :
+	PID(float p, float i, float d, float windup = 0, float dAlpha = 1) : p(p), i(i), d(d), windup(windup), lpf(dAlpha) {};
-		p(p), i(i), d(d), windup(windup), lpf(dAlpha), dtMax(dtMax) {}
 
-	float update(float error) {
+	float update(float error, float dt) {
-		float dt = t - prevTime;
-
-		if (dt > 0 && dt < dtMax) {
 		integral += error * dt;
-			derivative = lpf.update((error - prevError) / dt); // compute derivative and apply low-pass filter
+
-		} else {
+		if (isfinite(prevError) && dt > 0) {
-			integral = 0;
+			// calculate derivative if both dt and prevError are valid
-			derivative = 0;
+			derivative = (error - prevError) / dt;
+
+			// apply low pass filter to derivative
+			derivative = lpf.update(derivative);
 		}
 
 		prevError = error;
-		prevTime = t;
 
 		return p * error + constrain(i * integral, -windup, windup) + d * derivative; // PID
 	}
 
 	void reset() {
 		prevError = NAN;
-		prevTime = NAN;
 		integral = 0;
 		derivative = 0;
-		lpf.reset();
 	}
 
 private:
 	float prevError = NAN;
-	float prevTime = NAN;
 };

flix/power.ino

@@ -1,29 +0,0 @@
-// Copyright (c) 2026 Oleg Kalachev <okalachev@gmail.com>
-// Repository: https://github.com/okalachev/flix
-
-// Power management
-
-#include <soc/soc.h>
-#include <soc/rtc_cntl_reg.h>
-#include "lpf.h"
-#include "util.h"
-
-float voltage = NAN;
-LowPassFilter<float> voltageFilter(0.2);
-int voltagePin = -1;
-float voltageScale = 2;
-
-void setupPower() {
-	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA); // disable reset on low voltage
-	if (digitalPinToAnalogChannel(voltagePin) == -1) voltagePin = -1; // test ADC pin
-}
-
-void readVoltage() {
-	if (voltagePin < 0) return;
-
-	static Rate rate(10);
-	if (!rate) return;
-
-	float v = analogReadMilliVolts(voltagePin) * voltageScale / 1000.0f;
-	voltage = voltageFilter.update(v);
-}

flix/quaternion.h

@@ -45,7 +45,7 @@ public:
 			cx * cy * sz - sx * sy * cz);
 	}
 
-	static Quaternion fromBetweenVectors(const Vector& u, const Vector& v) {
+	static Quaternion fromBetweenVectors(Vector u, Vector v) {
 		float dot = u.x * v.x + u.y * v.y + u.z * v.z;
 		float w1 = u.y * v.z - u.z * v.y;
 		float w2 = u.z * v.x - u.x * v.z;
@@ -79,7 +79,6 @@ public:
 		z = NAN;
 	}
 
-
 	float norm() const {
 		return sqrt(w * w + x * x + y * y + z * z);
 	}
@@ -132,31 +131,29 @@ public:
 		return euler;
 	}
 
-	float getRoll() const {
-		return toEuler().x;
-	}
-
-	float getPitch() const {
-		return toEuler().y;
-	}
-
 	float getYaw() const {
-		return toEuler().z;
+		// https://github.com/ros/geometry2/blob/589caf083cae9d8fae7effdb910454b4681b9ec1/tf2/include/tf2/impl/utils.h#L122
+		float yaw;
+		float sqx = x * x;
+		float sqy = y * y;
+		float sqz = z * z;
+		float sqw = w * w;
+		double sarg = -2 * (x * z - w * y) / (sqx + sqy + sqz + sqw);
+		if (sarg <= -0.99999) {
+			yaw = -2 * atan2(y, x);
+		} else if (sarg >= 0.99999) {
+			yaw = 2 * atan2(y, x);
+		} else {
+			yaw = atan2(2 * (x * y + w * z), sqw + sqx - sqy - sqz);
 		}
-
+		return yaw;
-	void setRoll(float roll) {
-		Vector euler = toEuler();
-		*this = Quaternion::fromEuler(Vector(roll, euler.y, euler.z));
-	}
-
-	void setPitch(float pitch) {
-		Vector euler = toEuler();
-		*this = Quaternion::fromEuler(Vector(euler.x, pitch, euler.z));
 	}
 
 	void setYaw(float yaw) {
+		// TODO: optimize?
 		Vector euler = toEuler();
-		*this = Quaternion::fromEuler(Vector(euler.x, euler.y, yaw));
+		euler.z = yaw;
+		(*this) = Quaternion::fromEuler(euler);
 	}
 
 	Quaternion operator * (const Quaternion& q) const {

flix/rc.ino

@@ -6,33 +6,30 @@
 #include <SBUS.h>
 #include "util.h"
 
-SBUS rc(Serial1);
+SBUS RC(Serial2); // NOTE: Use RC(Serial2, 16, 17) if you use the old UART2 pins
-int rcRxPin = -1; // -1 means disabled
 
 uint16_t channels[16]; // raw rc channels
-int channelZero[16]; // calibration zero values
+double controlTime; // time of the last controls update
-int channelMax[16]; // calibration max values
+float channelZero[16]; // calibration zero values
+float channelMax[16]; // calibration max values
 
-float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
+// Channels mapping (using float to store in parameters):
-float controlMode = NAN;
+float rollChannel = NAN, pitchChannel = NAN, throttleChannel = NAN, yawChannel = NAN, armedChannel = NAN, modeChannel = NAN;
-float controlTime = NAN; // time of the last controls update
-
-int rollChannel = -1, pitchChannel = -1, throttleChannel = -1, yawChannel = -1, modeChannel = -1; // channel mapping
 
 void setupRC() {
-	if (rcRxPin < 0) return;
 	print("Setup RC\n");
-	rc.begin(rcRxPin);
+	RC.begin();
 }
 
 bool readRC() {
-	if (rcRxPin < 0) return false;
+	if (RC.read()) {
-	if (!rc.read()) return false;
+		SBUSData data = RC.data();
-
+		for (int i = 0; i < 16; i++) channels[i] = data.ch[i]; // copy channels data
-	rc.getChannels(channels);
 		normalizeRC();
 		controlTime = t;
 		return true;
+	}
+	return false;
 }
 
 void normalizeRC() {
@@ -41,35 +38,32 @@ void normalizeRC() {
 		controls[i] = mapf(channels[i], channelZero[i], channelMax[i], 0, 1);
 	}
 	// Update control values
-	controlRoll = rollChannel < 0 ? 0 : controls[rollChannel];
+	controlRoll = rollChannel >= 0 ? controls[(int)rollChannel] : NAN;
-	controlPitch = pitchChannel < 0 ? 0 : controls[pitchChannel];
+	controlPitch = pitchChannel >= 0 ? controls[(int)pitchChannel] : NAN;
-	controlYaw = yawChannel < 0 ? 0 : controls[yawChannel];
+	controlYaw = yawChannel >= 0 ? controls[(int)yawChannel] : NAN;
-	controlThrottle = throttleChannel < 0 ? 0 : controls[throttleChannel];
+	controlThrottle = throttleChannel >= 0 ? controls[(int)throttleChannel] : NAN;
-	controlMode = modeChannel < 0 ? NAN : controls[modeChannel]; // mode control is ineffective if not mapped
+	controlArmed = armedChannel >= 0 ? controls[(int)armedChannel] : 1; // assume armed by default
+	controlMode = modeChannel >= 0 ? controls[(int)modeChannel] : NAN;
 }
 
 void calibrateRC() {
-	if (rcRxPin < 0) {
+	uint16_t zero[16];
-		print("RC_RX_PIN = %d, set the RC pin!\n", rcRxPin);
+	uint16_t center[16];
-		return;
+	uint16_t max[16];
-	}
+	print("1/9 Calibrating RC: put all switches to default positions [3 sec]\n");
-
-	uint16_t zero[16]; // for zero positions
-	uint16_t center[16]; // for center positions
-	uint16_t _[16]; // for unused data
-	print("1/8 Calibrating RC: put all switches to default positions [3 sec]\n");
 	pause(3);
-	calibrateRCChannel(NULL, _, zero, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
+	calibrateRCChannel(NULL, zero, zero, "2/9 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
-	calibrateRCChannel(&throttleChannel, zero, _, "3/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
+	calibrateRCChannel(NULL, center, center, "3/9 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
-	calibrateRCChannel(NULL, _, center, "4/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
+	calibrateRCChannel(&throttleChannel, zero, max, "4/9 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
-	calibrateRCChannel(&yawChannel, center, _, "5/8 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
+	calibrateRCChannel(&yawChannel, center, max, "5/9 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
-	calibrateRCChannel(&pitchChannel, zero, _, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
+	calibrateRCChannel(&pitchChannel, zero, max, "6/9 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
-	calibrateRCChannel(&rollChannel, zero, _, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
+	calibrateRCChannel(&rollChannel, zero, max, "7/9 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
-	calibrateRCChannel(&modeChannel, zero, _, "8/8 Put mode switch to max [3 sec]\n");
+	calibrateRCChannel(&armedChannel, zero, max, "8/9 Switch to armed [3 sec]\n");
+	calibrateRCChannel(&modeChannel, zero, max, "9/9 Disarm and switch mode to max [3 sec]\n");
 	printRCCalibration();
 }
 
-void calibrateRCChannel(int *channel, uint16_t in[16], uint16_t out[16], const char *str) {
+void calibrateRCChannel(float *channel, uint16_t in[16], uint16_t out[16], const char *str) {
 	print("%s", str);
 	pause(3);
 	for (int i = 0; i < 30; i++) readRC(); // try update 30 times max
@@ -90,15 +84,16 @@ void calibrateRCChannel(int *channel, uint16_t in[16], uint16_t out[16], const c
 		channelZero[ch] = in[ch];
 		channelMax[ch] = out[ch];
 	} else {
-		*channel = -1;
+		*channel = NAN;
 	}
 }
 
 void printRCCalibration() {
 	print("Control   Ch     Zero   Max\n");
-	print("Roll      %-7d%-7d%-7d\n", rollChannel, rollChannel < 0 ? 0 : channelZero[rollChannel], rollChannel < 0 ? 0 : channelMax[rollChannel]);
+	print("Roll      %-7g%-7g%-7g\n", rollChannel, rollChannel >= 0 ? channelZero[(int)rollChannel] : NAN, rollChannel >= 0 ? channelMax[(int)rollChannel] : NAN);
-	print("Pitch     %-7d%-7d%-7d\n", pitchChannel, pitchChannel < 0 ? 0 : channelZero[pitchChannel], pitchChannel < 0 ? 0 : channelMax[pitchChannel]);
+	print("Pitch     %-7g%-7g%-7g\n", pitchChannel, pitchChannel >= 0 ? channelZero[(int)pitchChannel] : NAN, pitchChannel >= 0 ? channelMax[(int)pitchChannel] : NAN);
-	print("Yaw       %-7d%-7d%-7d\n", yawChannel, yawChannel < 0 ? 0 : channelZero[yawChannel], yawChannel < 0 ? 0 : channelMax[yawChannel]);
+	print("Yaw       %-7g%-7g%-7g\n", yawChannel, yawChannel >= 0 ? channelZero[(int)yawChannel] : NAN, yawChannel >= 0 ? channelMax[(int)yawChannel] : NAN);
-	print("Throttle  %-7d%-7d%-7d\n", throttleChannel, throttleChannel < 0 ? 0 : channelZero[throttleChannel], throttleChannel < 0 ? 0 : channelMax[throttleChannel]);
+	print("Throttle  %-7g%-7g%-7g\n", throttleChannel, throttleChannel >= 0 ? channelZero[(int)throttleChannel] : NAN, throttleChannel >= 0 ? channelMax[(int)throttleChannel] : NAN);
-	print("Mode      %-7d%-7d%-7d\n", modeChannel, modeChannel < 0 ? 0 : channelZero[modeChannel], modeChannel < 0 ? 0 : channelMax[modeChannel]);
+	print("Armed     %-7g%-7g%-7g\n", armedChannel, armedChannel >= 0 ? channelZero[(int)armedChannel] : NAN, armedChannel >= 0 ? channelMax[(int)armedChannel] : NAN);
+	print("Mode      %-7g%-7g%-7g\n", modeChannel, modeChannel >= 0 ? channelZero[(int)modeChannel] : NAN, modeChannel >= 0 ? channelMax[(int)modeChannel] : NAN);
 }

flix/time.ino

@@ -3,12 +3,10 @@
 
 // Time related functions
 
-float t = NAN; // current time, s
-float dt; // time delta with the previous step, s
 float loopRate; // Hz
 
 void step() {
-	float now = micros() / 1000000.0;
+	double now = micros() / 1000000.0;
 	dt = now - t;
 	t = now;
 
@@ -20,7 +18,7 @@ void step() {
 }
 
 void computeLoopRate() {
-	static float windowStart = 0;
+	static double windowStart = 0;
 	static uint32_t rate = 0;
 	rate++;
 	if (t - windowStart >= 1) { // 1 second window