Remove additional url to install esp32-core from arduino-cli config

2026-06-28 14:06:32 +00:00 · 2025-10-22 22:00:26 +03:00
108 changed files with 969 additions and 2241 deletions
@@ -23,10 +23,10 @@ jobs:
      with:
        name: firmware-binary
        path: flix/build
    - name: Build firmware for ESP32-C3
      run: make BOARD=esp32:esp32:esp32c3
    - name: Build firmware for ESP32-S3
      run: make BOARD=esp32:esp32:esp32s3
    - name: Build firmware with WiFi disabled
      run: sed -i 's/^#define WIFI_ENABLED 1$/#define WIFI_ENABLED 0/' flix/flix.ino && make
    - name: Check c_cpp_properties.json
      run: tools/check_c_cpp_properties.py
@@ -7,8 +7,6 @@
 	"MD024": false,
 	"MD033": false,
 	"MD034": false,
 	"MD040": false,
 	"MD059": false,
 	"MD044": {
 		"html_elements": false,
 		"code_blocks": false,
@@ -66,6 +64,5 @@
 			"PX4"
 		]
 	},
-	"MD045": false,
+	"MD045": false
 	"MD060": false
 }
@@ -6,20 +6,34 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
 				"~/.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/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h"
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
 				"${workspaceFolder}/flix/flix.ino",
 				"${workspaceFolder}/flix/imu.ino",
 				"${workspaceFolder}/flix/led.ino",
 				"${workspaceFolder}/flix/log.ino",
 				"${workspaceFolder}/flix/mavlink.ino",
 				"${workspaceFolder}/flix/motors.ino",
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
 				"${workspaceFolder}/flix/parameters.ino"
 			],
-			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -39,20 +53,34 @@
 			"name": "Mac",
 			"includePath": [
 				"${workspaceFolder}/flix",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/include/**",
 				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**",
 				"/opt/homebrew/include/gazebo-11/",
 				"/opt/homebrew/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/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",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
 				"${workspaceFolder}/flix/imu.ino",
 				"${workspaceFolder}/flix/led.ino",
 				"${workspaceFolder}/flix/log.ino",
 				"${workspaceFolder}/flix/mavlink.ino",
 				"${workspaceFolder}/flix/motors.ino",
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
 				"${workspaceFolder}/flix/parameters.ino"
 			],
-			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -75,18 +103,32 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
 				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h"
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
 				"${workspaceFolder}/flix/flix.ino",
 				"${workspaceFolder}/flix/imu.ino",
 				"${workspaceFolder}/flix/led.ino",
 				"${workspaceFolder}/flix/log.ino",
 				"${workspaceFolder}/flix/mavlink.ino",
 				"${workspaceFolder}/flix/motors.ino",
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
 				"${workspaceFolder}/flix/parameters.ino"
 			],
-			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2511/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": [
@@ -1,5 +1,6 @@
 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))
 build: .dependencies
 	arduino-cli compile --fqbn $(BOARD) flix
@@ -12,16 +13,12 @@ monitor:
 dependencies .dependencies:
 	arduino-cli core update-index --config-file arduino-cli.yaml
-	arduino-cli core install esp32:esp32@3.3.6 --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@3.2.0 --config-file arduino-cli.yaml
 	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 .dependencies
 upload_proxy: .dependencies
 	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 ..
@@ -35,7 +32,7 @@ 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)
@@ -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>
@@ -21,13 +18,15 @@
 * Dedicated for education and research.
 * Made from general-purpose components.
 * Simple and clean source code in Arduino (<2k lines firmware).
-* Communication using MAVLink protocol over Wi-Fi or ESP-NOW.
+* Control using USB gamepad, remote control or smartphone.
-* Control with USB gamepad, remote control or smartphone.
+* Wi-Fi and MAVLink support.
 * Wireless command line interface and analyzing.
 * Precise simulation with Gazebo.
-* Python library for scripting and automatic flights.
+* 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
@@ -53,47 +52,45 @@ 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).
+* [Usage: build, setup and flight](docs/usage.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>ICM20948V2 (ICM‑20948)³<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">Buck-boost converter</span> (recommended)|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 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` or `MPU6050` in `imu.ino` file for using the appropriate boards.*<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 also may use any transmitter-receiver pair with SBUS interface.*
 Tools required for assembly:
@@ -103,7 +100,7 @@ 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
@@ -111,7 +108,7 @@ Feel free to modify the design and or code, and create your own improved version
 <img src="docs/img/schematics1.svg" width=700 alt="Flix version 1 schematics">
-*(Dashed elements are optional).*
+*(Dashed is optional).*
 Motor connection scheme:
@@ -119,6 +116,8 @@ 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.
@@ -136,15 +135,14 @@ 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:
@@ -152,20 +150,32 @@ 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!
@@ -1,5 +1,2 @@
 board_manager:
  additional_urls:
    - https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
 network:
  connection_timeout: 1h
@@ -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>
@@ -12,8 +12,8 @@
 * `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
@@ -35,7 +35,7 @@
 ### Подсистема управления
-Состояние органов управления обрабатывается в функции `interpretControls()` и преобразуется в **команду управления**, которая включает следующее:
+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*.
@@ -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) \\]
@@ -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;
@@ -1,2 +0,0 @@
 <!-- markdownlint-disable MD041 -->
 Build instructions are moved to [usage article](usage.md).
@@ -0,0 +1 @@
 usage.md
@@ -6,7 +6,7 @@ The firmware is a regular Arduino sketch, and it follows the classic Arduino one
 <img src="img/dataflow.svg" width=600 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 goes through global variables (for simplicity):
 * `t` *(float)* — current step time, *s*.
 * `dt` *(float)* — time delta between the current and previous steps, *s*.
@@ -14,12 +14,12 @@ The main loop is running at 1000 Hz. The dataflow goes through global variables,
 * `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 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 core files are:
 * [`flix.ino`](../flix/flix.ino) — Arduino sketch main file, entry point.Includes some global variable definitions and the main loop.
 * [`imu.ino`](../flix/imu.ino) — reading data from the IMU sensor (gyroscope and accelerometer), IMU calibration.
@@ -28,7 +28,6 @@ Firmware source files are located in `flix` directory.
 * [`control.ino`](../flix/control.ino) — control subsystem, three-dimensional two-level cascade PID controller.
 * [`motors.ino`](../flix/motors.ino) — PWM motor output 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:
@@ -38,64 +37,20 @@ Utility files:
 ### Control subsystem
-Pilot inputs are interpreted in `interpretControls()`, and then converted to the **control command**, which consists of the following:
+Pilot inputs are interpreted in `interpretControls()`, and then converted to the *control command*, which consists of the following:
 * `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*.
+* `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].
+* `thrustTarget` *(float)* — collective 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`.
+Control command is processed in `controlAttitude()`, `controlRates()`, `controlTorque()` functions. Each function may be skipped if the corresponding 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
+## Building
 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).
 ## 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).
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 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
@@ -4,7 +4,7 @@
 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](usage.md#firmware).
 * **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*.
@@ -12,36 +12,26 @@ Do the following:
 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/MPU-6050 board, change `MPU9250` to `ICM20948`/`MPU6050` 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:
+* **Check the remote control**. Using `rc` command, check the control values reflect your sticks movement. All the controls should change between -1 and 1, and throttle between 0 and 1.
-
+* If using SBUS receiver, **calibrate the RC**. Type `cr` command in Serial Monitor and follow the instructions.
-  <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.
 * **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.
@@ -1,38 +1,130 @@
 # 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 use Flix, you need to build the firmware and upload it to the ESP32 board. For simulation, you need to build and run the simulator.
-To get the firmware sources, clone the repository using git:
+For the start, clone the repository using git:
 ```bash
-git clone https://github.com/okalachev/flix.git && cd flix
+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).
+## Simulation
-## Building the firmware
+### Ubuntu
-You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
+The latest version of Ubuntu supported by Gazebo 11 simulator is 20.04. 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
   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
   ```
   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
 #### 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)
 <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).*
+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 3.3.6. 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.
+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 2.0.25.
+   * `MAVLink`, version 2.0.16.
-5. Open the `flix/flix.ino` sketch from downloaded firmware sources in Arduino IDE.
+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. 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.
+6. Open the downloaded Arduino sketch `flix/flix.ino` in Arduino IDE.
-7. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using 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, install it like this:
+   On Linux, use:
   ```bash
   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
@@ -57,152 +149,19 @@ You can build and upload the firmware using either **Arduino IDE** (easier for b
   make upload monitor
   ```
-See other available Make commands in [Makefile](../Makefile).
+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 console and QGroundControl connection should work.
+> 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.
-## Before first flight
+### Setup
 ### 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.
 ### 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.
+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.
-### Setup motors
+#### Control with smartphone
 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.
@@ -212,19 +171,17 @@ There are several ways to control the drone's flight: using **smartphone** (Wi-F
 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.
+> Decrease `TILT_MAX` parameter when flying using the smartphone to make the controls less sensitive.
-### Control with a remote control
+#### Control with remote control
-If using SBUS-connected remote control you need to enable SBUS and calibrate it:
+Before flight using remote control, you need to calibrate it:
-1. Connect to the drone using QGroundControl.
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
-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.
+2. Type `cr` command there and follow the instructions.
-3. Check if the receiver is working using `rc` command in the console.
+3. Use the remote control to fly the drone!
 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
+#### Control with USB remote control (Wi-Fi)
 If your drone doesn't have RC receiver installed, you can use USB remote control and QGroundControl app to fly it.
@@ -236,6 +193,9 @@ If your drone doesn't have RC receiver installed, you can use USB remote control
 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!
 > [!NOTE]
 > If something goes wrong, go to the [Troubleshooting](troubleshooting.md) article.
 ## 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:
@@ -254,16 +214,13 @@ When finished flying, **disarm** the drone, moving the left stick to the bottom
 <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*).
+Flight mode is changed using mode switch on the remote control or using the command line.
 #### 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.
+The default mode is *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.
@@ -272,84 +229,24 @@ In this mode, the drone stabilizes its attitude (orientation). The left stick co
 In this mode, the pilot controls the angular rates. This control method is difficult to fly and mostly used in FPV racing.
-#### RAW
+#### MANUAL
-*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**.
+Manual mode disables all the stabilization, and the pilot inputs are passed directly to the motors. 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.
+In this mode, the pilot inputs are ignored (except the mode switch, if configured). The drone can be controlled using [pyflix](../tools/pyflix/) Python library, or by modifying the firmware to implement the needed autonomous behavior.
-If the pilot moves the control sticks and mode switch is not configured, the drone will switch back to *STAB* mode.
+If the pilot moves the control sticks, the drone will switch back to *STAB* mode.
-## Wi-Fi configuration
+## Adjusting parameters
-You can configure the Wi-Fi using parameters and console commands.
+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*.
-The Wi-Fi mode is chosen using `WIFI_MODE` parameter in QGroundControl or in the console:
+<img src="img/parameters.png" width="400">
-* `0` — Wi-Fi is disabled.
+## CLI access
 * `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:
+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">
 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.
 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.
@@ -4,110 +4,12 @@ This page contains user-built drones based on the Flix project. Publish your pro
 ---
 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>
 ---
 ## 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).
+Some of the designed model files: 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.
@@ -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|||
@@ -3,33 +3,26 @@
 // Implementation of command line interface
 #include <Arduino.h>
 #include "flix.h"
 #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 const int ACRO, STAB, AUTO;
 extern const int W_AP, W_STA, W_ESPNOW;
 extern float t, dt, loopRate;
 extern uint16_t channels[16];
-extern float controlTime;
+extern float controlRoll, controlPitch, controlThrottle, controlYaw, 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"
@@ -42,15 +35,10 @@ const char* motd =
 "imu - show IMU data\n"
 "arm - arm the drone\n"
 "disarm - disarm the drone\n"
-"raw/stab/acro/auto - set mode\n"
+"stab/acro/auto - set mode\n"
 "rc - show RC data\n"
 "pw - show power info\n"
 "wifi - show Wi-Fi info\n"
 "ap <ssid> <password> - setup Wi-Fi access point\n"
 "sta <ssid> <password> - setup Wi-Fi client mode\n"
 "espnow <mac> [<key>] - setup 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"
@@ -65,7 +53,9 @@ void print(const char* format, ...) {
 	vsnprintf(buf, sizeof(buf), format, args);
 	va_end(args);
 	Serial.print(buf);
 #if WIFI_ENABLED
 	mavlinkPrint(buf);
 #endif
 }
 void pause(float duration) {
@@ -73,12 +63,14 @@ void pause(float duration) {
 	while (t - start < duration) {
 		step();
 		handleInput();
 #if WIFI_ENABLED
 		processMavlink();
 #endif
 		delay(50);
 	}
 }
-void doCommand(String str, bool echo) {
+void doCommand(String str, bool echo = false) {
 	// parse command
 	String command, arg0, arg1;
 	splitString(str, command, arg0, arg1);
@@ -101,7 +93,7 @@ void doCommand(String str, bool echo) {
 	} 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());
 		}
@@ -124,8 +116,6 @@ void doCommand(String str, bool echo) {
 		armed = true;
 	} else if (command == "disarm") {
 		armed = false;
 	} else if (command == "raw") {
 		mode = RAW;
 	} else if (command == "stab") {
 		mode = STAB;
 	} else if (command == "acro") {
@@ -139,25 +129,13 @@ void doCommand(String str, bool echo) {
 		}
 		print("\nroll: %g pitch: %g yaw: %g throttle: %g mode: %g\n",
 			controlRoll, controlPitch, controlYaw, controlThrottle, 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") {
 		printWiFiInfo();
 	} 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") {
@@ -175,7 +153,6 @@ void doCommand(String str, bool echo) {
 		print("Chip: %s\n", ESP.getChipModel());
 		print("Temperature: %.1f °C\n", temperatureRead());
 		print("Free heap: %d\n", ESP.getFreeHeap());
 		print("Firmware: " __DATE__ " " __TIME__ "\n");
 		// Print tasks table
 		print("Num  Task                Stack  Prio  Core  CPU%%\n");
 		int taskCount = uxTaskGetNumberOfTasks();
@@ -186,13 +163,12 @@ void doCommand(String str, bool echo) {
 			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 {
@@ -1,55 +0,0 @@
 // Wi-Fi
 #define WIFI_ENABLED 1
 #define WIFI_SSID "flix"
 #define WIFI_PASSWORD "flixwifi"
 #define WIFI_UDP_PORT 14550
 #define WIFI_UDP_REMOTE_PORT 14550
 #define WIFI_UDP_REMOTE_ADDR "255.255.255.255"
 // Motors
 #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
 #define PWM_FREQUENCY 78000
 #define PWM_RESOLUTION 10
 #define PWM_STOP 0
 #define PWM_MIN 0
 #define PWM_MAX 1000000 / PWM_FREQUENCY
 // Control
 #define PITCHRATE_P 0.05
 #define PITCHRATE_I 0.2
 #define PITCHRATE_D 0.001
 #define PITCHRATE_I_LIM 0.3
 #define ROLLRATE_P PITCHRATE_P
 #define ROLLRATE_I PITCHRATE_I
 #define ROLLRATE_D PITCHRATE_D
 #define ROLLRATE_I_LIM PITCHRATE_I_LIM
 #define YAWRATE_P 0.3
 #define YAWRATE_I 0.0
 #define YAWRATE_D 0.0
 #define YAWRATE_I_LIM 0.3
 #define ROLL_P 6
 #define ROLL_I 0
 #define ROLL_D 0
 #define PITCH_P ROLL_P
 #define PITCH_I ROLL_I
 #define PITCH_D ROLL_D
 #define YAW_P 3
 #define PITCHRATE_MAX radians(360)
 #define ROLLRATE_MAX radians(360)
 #define YAWRATE_MAX radians(300)
 #define TILT_MAX radians(30)
 #define RATES_D_LPF_ALPHA 0.2 // cutoff frequency ~ 40 Hz
 // Estimation
 #define WEIGHT_ACC 0.003
 #define RATES_LFP_ALPHA 0.2 // cutoff frequency ~ 40 Hz
 // MAVLink
 #define SYSTEM_ID 1
 // Safety
 #define RC_LOSS_TIMEOUT 1
 #define DESCEND_TIME 10
@@ -3,25 +3,41 @@
 // Flight control
 #include "config.h"
 #include "flix.h"
 #include "vector.h"
 #include "quaternion.h"
 #include "pid.h"
 #include "lpf.h"
 #include "util.h"
-extern const int RAW = 0, ACRO = 1, STAB = 2, AUTO = 3; // flight modes
+#define PITCHRATE_P 0.05
 #define PITCHRATE_I 0.2
 #define PITCHRATE_D 0.001
 #define PITCHRATE_I_LIM 0.3
 #define ROLLRATE_P PITCHRATE_P
 #define ROLLRATE_I PITCHRATE_I
 #define ROLLRATE_D PITCHRATE_D
 #define ROLLRATE_I_LIM PITCHRATE_I_LIM
 #define YAWRATE_P 0.3
 #define YAWRATE_I 0.0
 #define YAWRATE_D 0.0
 #define YAWRATE_I_LIM 0.3
 #define ROLL_P 6
 #define ROLL_I 0
 #define ROLL_D 0
 #define PITCH_P ROLL_P
 #define PITCH_I ROLL_I
 #define PITCH_D ROLL_D
 #define YAW_P 3
 #define PITCHRATE_MAX radians(360)
 #define ROLLRATE_MAX radians(360)
 #define YAWRATE_MAX radians(300)
 #define TILT_MAX radians(30)
 #define RATES_D_LPF_ALPHA 0.2 // cutoff frequency ~ 40 Hz
 const int MANUAL = 0, ACRO = 1, STAB = 2, AUTO = 3; // flight modes
 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);
@@ -30,7 +46,12 @@ 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;
@@ -44,17 +65,16 @@ 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 = STAB;
 	if (mode == AUTO) return; // pilot is not effective in AUTO mode
 	if (controlThrottle < 0.05 && controlYaw > 0.95) armed = true; // arm gesture
 	if (controlThrottle < 0.05 && controlYaw < -0.95) armed = false; // disarm gesture
 	if (abs(controlYaw) < 0.1) controlYaw = 0; // yaw dead zone
 	thrustTarget = controlThrottle;
 	if (mode == STAB) {
@@ -71,10 +91,10 @@ void interpretControls() {
 		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
 		ratesTarget.invalidate(); // skip rate control
-		torqueTarget = Vector(controlRoll, controlPitch, -controlYaw) * 0.1;
+		torqueTarget = Vector(controlRoll, controlPitch, -controlYaw) * 0.01;
 	}
 }
@@ -127,28 +147,15 @@ void controlTorque() {
 	motors[MOTOR_REAR_LEFT] = thrustTarget + torqueTarget.x + torqueTarget.y - torqueTarget.z;
 	motors[MOTOR_REAR_RIGHT] = thrustTarget - torqueTarget.x + torqueTarget.y + torqueTarget.z;
 	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";
@@ -1,31 +1,24 @@
 // 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 "config.h"
 #include "flix.h"
 #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;
 float levelWeight = 0.0002;
 LowPassFilter<Vector> ratesFilter(0.2); // cutoff frequency ~ 40 Hz
 void estimate() {
 	applyGyro();
 	applyAcc();
 	applyLevel();
 }
 void applyGyro() {
 	// filter gyro to get angular rates
 	static LowPassFilter<Vector> ratesFilter(RATES_LFP_ALPHA);
 	rates = ratesFilter.update(gyro);
 	// apply rates to attitude
@@ -41,17 +34,8 @@ void applyAcc() {
 	// 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;
 	// 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));
 }
@@ -1,95 +0,0 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // All-in-one header file
 #pragma once
 #include <Arduino.h>
 #include "vector.h"
 #include "quaternion.h"
 extern float t, dt;
 extern float loopRate;
 extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
 extern Vector gyro, acc;
 extern Vector rates;
 extern Quaternion attitude;
 extern bool landed;
 extern int mode;
 extern bool armed;
 extern Quaternion attitudeTarget;
 extern Vector ratesTarget, ratesExtra, torqueTarget;
 extern float thrustTarget;
 extern float motors[4];
 void print(const char* format, ...);
 void pause(float duration);
 void doCommand(String str, bool echo = false);
 void handleInput();
 void control();
 void interpretControls();
 void controlAttitude();
 void controlRates();
 void controlTorque();
 void desaturate(float& a, float& b, float& c, float& d);
 const char *getModeName();
 void estimate();
 void applyGyro();
 void applyAcc();
 void applyLevel();
 void setupIMU();
 void configureIMU();
 void readIMU();
 void rotateIMU(Vector& data);
 void calibrateGyroOnce();
 void calibrateAccel();
 void calibrateAccelOnce();
 void printIMUCalibration();
 void printIMUInfo();
 void setupLED();
 void setLED(bool on);
 void blinkLED();
 void prepareLogData();
 void logData();
 void printLogHeader();
 void printLogData();
 void processMavlink();
 void sendMavlink();
 void sendMessage(const void *msg);
 void receiveMavlink();
 void printWiFiInfo();
 void configWiFi(int mode, const char *first, const char *second);
 void handleMavlink(const void *_msg);
 void mavlinkPrint(const char* str);
 void sendMavlinkPrint();
 void setupMotors();
 int getDutyCycle(float value);
 void sendMotors();
 bool motorsActive();
 void testMotor(int n);
 void setupParameters();
 int parametersCount();
 const char *getParameterName(int index);
 float getParameter(int index);
 float getParameter(const char *name);
 bool setParameter(const char *name, const float value);
 void syncParameters();
 void printParameters();
 void resetParameters();
 void setupRC();
 bool readRC();
 void normalizeRC();
 void calibrateRC();
 void calibrateRCChannel(int *channel, uint16_t in[16], uint16_t out[16], const char *str);
 void printRCCalibration();
 void setupPower();
 void failsafe();
 void rcLossFailsafe();
 void descend();
 void autoFailsafe();
 void step();
 void computeLoopRate();
 void setupWiFi();
 void sendWiFi(const uint8_t *buf, int len);
 int receiveWiFi(uint8_t *buf, int len);
@@ -3,21 +3,35 @@
 // Main firmware file
 #include "config.h"
 #include "vector.h"
 #include "quaternion.h"
 #include "util.h"
-#include "flix.h"
+
 #define SERIAL_BAUDRATE 115200
 #define WIFI_ENABLED 1
 float t = NAN; // current step time, s
 float dt; // time delta from previous step, s
 float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
 float 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);
@@ -32,8 +46,9 @@ void loop() {
 	control();
 	sendMotors();
 	handleInput();
 #if WIFI_ENABLED
 	processMavlink();
-	readVoltage();
+#endif
 	logData();
 	syncParameters();
 }
@@ -10,16 +10,10 @@
 #include "util.h"
 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");
@@ -43,16 +37,24 @@ void readIMU() {
 	// apply scale and bias
 	acc = (acc - accBias) / accScale;
 	gyro = gyro - gyroBias;
-	// rotate to body frame
+	// rotate
-	Quaternion rotation = Quaternion::fromEuler(imuRotation);
+	rotateIMU(acc);
-	acc = Quaternion::rotateVector(acc, rotation.inversed());
+	rotateIMU(gyro);
-	gyro = Quaternion::rotateVector(gyro, rotation.inversed());
+}
 void rotateIMU(Vector& data) {
 	// Rotate from LFD to FLU
 	// NOTE: In case of using other IMU orientation, change this line:
 	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);
 	if (!landedDelay.update(landed)) return; // calibrate only if definitely stationary
-	gyroBias = gyroBiasFilter.update(gyro);
+
 	static LowPassFilter<Vector> gyroCalibrationFilter(0.001);
 	gyroBias = gyroCalibrationFilter.update(gyro);
 }
 void calibrateAccel() {
@@ -121,7 +123,7 @@ void printIMUInfo() {
 	print("model: %s\n", imu.getModel());
 	print("who am I: 0x%02X\n", imu.whoAmI());
 	print("rate: %.0f\n", loopRate);
-	print("gyro: %f %f %f\n", gyro.x, gyro.y, gyro.z);
+	print("gyro: %f %f %f\n", rates.x, rates.y, rates.z);
 	print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
 	imu.waitForData();
 	Vector rawGyro, rawAcc;
@@ -3,8 +3,6 @@
 // Board's LED control
 #include <Arduino.h>
 #define BLINK_PERIOD 500000
 #ifndef LED_BUILTIN
@@ -3,12 +3,11 @@
 // In-RAM logging
 #include "flix.h"
 #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
 Vector attitudeEuler;
@@ -47,8 +46,9 @@ void prepareLogData() {
 void logData() {
 	if (!armed) return;
 	static int logPointer = 0;
-	static Rate period(LOG_RATE);
+	static float logTime = 0;
-	if (!period) return;
+	if (t - logTime < LOG_PERIOD) return;
 	logTime = t;
 	prepareLogData();
@@ -62,13 +62,12 @@ 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++) {
@@ -5,8 +5,6 @@
 #pragma once
 #include <Arduino.h>
 template <typename T> // Using template to make the filter usable for scalar and vector values
 class LowPassFilter {
 public:
@@ -16,10 +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);
 	}
@@ -28,9 +31,9 @@ public:
 	}
 	void reset() {
-		init = false;
+		initialized = false;
 	}
 private:
-	bool init = false;
+	bool initialized = false;
 };
@@ -3,22 +3,20 @@
 // MAVLink communication
-#include <Arduino.h>
+#if WIFI_ENABLED
 #include <MAVLink.h>
 #include "config.h"
 #include "util.h"
-extern const int RAW, ACRO, STAB, AUTO;
+#define SYSTEM_ID 1
-extern float controlTime;
+#define PERIOD_SLOW 1.0
-extern float voltage;
+#define PERIOD_FAST 0.1
-extern uint16_t channels[16];
+#define MAVLINK_CONTROL_YAW_DEAD_ZONE 0.1f
 int mavlinkSysId = 1;
 Rate telemetryFast(10);
 Rate telemetrySlow(2);
 bool mavlinkConnected = false;
-static String mavlinkPrintBuffer;
+String mavlinkPrintBuffer;
 extern float controlTime;
 extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlMode;
 void processMavlink() {
 	sendMavlink();
@@ -28,11 +26,16 @@ void processMavlink() {
 void sendMavlink() {
 	sendMavlinkPrint();
 	static float lastSlow = 0;
 	static float 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;
 		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
 			(armed ? MAV_MODE_FLAG_SAFETY_ARMED : 0) |
 			((mode == STAB) ? MAV_MODE_FLAG_STABILIZE_ENABLED : 0) |
 			((mode == AUTO) ? MAV_MODE_FLAG_AUTO_ENABLED : MAV_MODE_FLAG_MANUAL_INPUT_ENABLED),
@@ -41,35 +44,30 @@ void sendMavlink() {
 		if (!mavlinkConnected) return; // send only heartbeat until connected
-		mavlink_msg_extended_sys_state_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_extended_sys_state_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			MAV_VTOL_STATE_UNDEFINED, landed ? MAV_LANDED_STATE_ON_GROUND : MAV_LANDED_STATE_IN_AIR);
 		sendMessage(&msg);
 		uint16_t voltages[] = {voltage * 1000, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX};
 		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);
 		if (valid(voltage)) sendMessage(&msg);
 	}
-	if (telemetryFast && mavlinkConnected) {
+	if (t - lastFast >= PERIOD_FAST && mavlinkConnected) {
-		const float offset[] = {0, 0, 0, 0};
+		lastFast = t;
-		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, offset); // convert to frd
+		const float zeroQuat[] = {0, 0, 0, 0};
 		mavlink_msg_attitude_quaternion_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, zeroQuat); // convert to frd
 		sendMessage(&msg);
-		mavlink_msg_rc_channels_raw_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, controlTime * 1000, 0,
+		mavlink_msg_rc_channels_raw_pack(SYSTEM_ID, 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);
 		if (channels[0] != 0) sendMessage(&msg); // 0 means no RC input
 		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);
-		mavlink_msg_scaled_imu_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time,
+		mavlink_msg_scaled_imu_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time,
-			acc.x / ONE_G * 1000, -acc.y / ONE_G * 1000, -acc.z / ONE_G * 1000, // convert to frd
+			acc.x * 1000, -acc.y * 1000, -acc.z * 1000, // convert to frd
 			gyro.x * 1000, -gyro.y * 1000, -gyro.z * 1000,
 			0, 0, 0, 0);
 		sendMessage(&msg);
@@ -103,7 +101,7 @@ 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;
@@ -111,16 +109,18 @@ void handleMavlink(const void *_msg) {
 		controlYaw = m.r / 1000.0f;
 		controlMode = 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);
 		}
@@ -129,7 +129,7 @@ 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
@@ -138,7 +138,7 @@ 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);
 	}
@@ -146,33 +146,32 @@ 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
@@ -184,7 +183,7 @@ 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;
@@ -206,7 +205,7 @@ 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();
@@ -215,33 +214,17 @@ void handleMavlink(const void *_msg) {
 		armed = motors[0] > 0 || motors[1] > 0 || motors[2] > 0 || motors[3] > 0;
 	}
 	/* TODO:
 	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 response;
 		bool accepted = false;
 		if (m.command == MAV_CMD_REQUEST_MESSAGE && m.param1 == MAVLINK_MSG_ID_AUTOPILOT_VERSION) {
 			accepted = true;
-			mavlink_msg_autopilot_version_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &response,
+			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);
 		}
@@ -260,7 +243,7 @@ void handleMavlink(const void *_msg) {
 		// 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);
+		mavlink_msg_command_ack_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, accepted ? MAV_RESULT_ACCEPTED : MAV_RESULT_UNSUPPORTED, UINT8_MAX, 0, msg.sysid, msg.compid);
 		sendMessage(&ack);
 	}
 }
@@ -277,7 +260,7 @@ 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);
@@ -285,3 +268,5 @@ void sendMavlinkPrint() {
 	}
 	mavlinkPrintBuffer.clear();
 }
 #endif
@@ -1,64 +0,0 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // PWM control for motors
 #include <Arduino.h>
 #include "config.h"
 #include "flix.h"
 #include "util.h"
 float motors[4]; // normalized motor thrusts in range [0..1]
 int motorPins[4] = {12, 13, 14, 15}; // default pin numbers
 int pwmFrequency = 78000;
 int pwmResolution = 10;
 int pwmStop = 0;
 int pwmMin = 0;
 int pwmMax = -1; // -1 means duty cycle mode
 extern const int MOTOR_REAR_LEFT = 0, MOTOR_REAR_RIGHT = 1, MOTOR_FRONT_RIGHT = 2, MOTOR_FRONT_LEFT = 3;
 void setupMotors() {
 	print("Setup Motors\n");
 	// configure pins
 	for (int i = 0; i < 4; i++) {
 		ledcAttach(motorPins[i], pwmFrequency, pwmResolution);
 		pwmFrequency = ledcChangeFrequency(motorPins[i], pwmFrequency, pwmResolution); // when reconfiguring
 	}
 	sendMotors();
 	print("Motors initialized\n");
 }
 void sendMotors() {
 	for (int i = 0; i < 4; i++) {
 		ledcWrite(motorPins[i], getDutyCycle(motors[i]));
 	}
 }
 int getDutyCycle(float value) {
 	value = constrain(value, 0, 1);
 	if (pwmMax >= 0) { // pwm mode
 		float pwm = mapf(value, 0, 1, pwmMin, pwmMax);
 		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));
 	}
 }
 bool motorsActive() {
 	return motors[0] != 0 || motors[1] != 0 || motors[2] != 0 || motors[3] != 0;
 }
 void testMotor(int n) {
 	print("Testing motor %d\n", n);
 	motors[n] = 0.2;
 	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);
 	motors[n] = 0;
 	sendMotors();
 	print("Done\n");
 }
@@ -0,0 +1,67 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // 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"
 #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
 #define PWM_FREQUENCY 78000
 #define PWM_RESOLUTION 10
 #define PWM_STOP 0
 #define PWM_MIN 0
 #define PWM_MAX 1000000 / PWM_FREQUENCY
 // 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
 	ledcAttach(MOTOR_0_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
 	ledcAttach(MOTOR_1_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
 	ledcAttach(MOTOR_2_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
 	ledcAttach(MOTOR_3_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
 	sendMotors();
 	print("Motors initialized\n");
 }
 int getDutyCycle(float value) {
 	value = constrain(value, 0, 1);
 	float pwm = mapff(value, 0, 1, PWM_MIN, PWM_MAX);
 	if (value == 0) pwm = PWM_STOP;
 	float duty = mapff(pwm, 0, 1000000 / PWM_FREQUENCY, 0, (1 << PWM_RESOLUTION) - 1);
 	return round(duty);
 }
 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() {
 	return motors[0] != 0 || motors[1] != 0 || motors[2] != 0 || motors[3] != 0;
 }
 void testMotor(int n) {
 	print("Testing motor %d\n", n);
 	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);
 	motors[n] = 0;
 	sendMotors();
 	print("Done\n");
 }
@@ -1,217 +0,0 @@
 // Copyright (c) 2024 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // Parameters storage in flash memory
 #include <Preferences.h>
 #include "flix.h"
 #include "pid.h"
 #include "lpf.h"
 #include "util.h"
 extern float channelZero[16], channelMax[16];
 extern float rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
 extern float tiltMax;
 extern int flightModes[3];
 extern PID rollPID, pitchPID, yawPID;
 extern PID rollRatePID, pitchRatePID, yawRatePID;
 extern Vector maxRate;
 extern Vector imuRotation;
 extern Vector accBias, accScale;
 extern float accWeight, levelWeight;
 extern LowPassFilter<Vector> gyroBiasFilter, ratesFilter, voltageFilter;
 extern int rcRxPin, voltagePin;
 extern int motorPins[4];
 extern int pwmFrequency, pwmResolution, pwmStop, pwmMin, pwmMax;
 extern int wifiMode, wifiLongRange, udpLocalPort, udpRemotePort, espnowChannel;
 extern int mavlinkSysId;
 extern Rate telemetrySlow, telemetryFast;
 extern float rcLossTimeout, descendTime;
 extern int voltagePin;
 extern float voltageScale;
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
 Preferences storage;
 struct Parameter {
 	const char *name; // max length is 15
 	bool integer;
 	union { float *f; int *i; }; // pointer to the variable
 	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; };
 };
 static Parameter parameters[] = {
 	// control
 	{"CTL_R_RATE_P", &rollRatePID.p},
 	{"CTL_R_RATE_I", &rollRatePID.i},
 	{"CTL_R_RATE_D", &rollRatePID.d},
 	{"CTL_R_RATE_WU", &rollRatePID.windup},
 	{"CTL_R_RATE_D_A", &rollRatePID.lpf.alpha},
 	{"CTL_P_RATE_P", &pitchRatePID.p},
 	{"CTL_P_RATE_I", &pitchRatePID.i},
 	{"CTL_P_RATE_D", &pitchRatePID.d},
 	{"CTL_P_RATE_WU", &pitchRatePID.windup},
 	{"CTL_P_RATE_D_A", &pitchRatePID.lpf.alpha},
 	{"CTL_Y_RATE_P", &yawRatePID.p},
 	{"CTL_Y_RATE_I", &yawRatePID.i},
 	{"CTL_Y_RATE_D", &yawRatePID.d},
 	{"CTL_Y_RATE_D_A", &yawRatePID.lpf.alpha},
 	{"CTL_R_P", &rollPID.p},
 	{"CTL_R_I", &rollPID.i},
 	{"CTL_R_D", &rollPID.d},
 	{"CTL_P_P", &pitchPID.p},
 	{"CTL_P_I", &pitchPID.i},
 	{"CTL_P_D", &pitchPID.d},
 	{"CTL_Y_P", &yawPID.p},
 	{"CTL_P_RATE_MAX", &maxRate.y},
 	{"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},
 	{"IMU_ROT_PITCH", &imuRotation.y},
 	{"IMU_ROT_YAW", &imuRotation.z},
 	{"IMU_ACC_BIAS_X", &accBias.x},
 	{"IMU_ACC_BIAS_Y", &accBias.y},
 	{"IMU_ACC_BIAS_Z", &accBias.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]},
 	{"RC_ZERO_3", &channelZero[3]},
 	{"RC_ZERO_4", &channelZero[4]},
 	{"RC_ZERO_5", &channelZero[5]},
 	{"RC_ZERO_6", &channelZero[6]},
 	{"RC_ZERO_7", &channelZero[7]},
 	{"RC_MAX_0", &channelMax[0]},
 	{"RC_MAX_1", &channelMax[1]},
 	{"RC_MAX_2", &channelMax[2]},
 	{"RC_MAX_3", &channelMax[3]},
 	{"RC_MAX_4", &channelMax[4]},
 	{"RC_MAX_5", &channelMax[5]},
 	{"RC_MAX_6", &channelMax[6]},
 	{"RC_MAX_7", &channelMax[7]},
 	{"RC_ROLL", &rollChannel},
 	{"RC_PITCH", &pitchChannel},
 	{"RC_THROTTLE", &throttleChannel},
 	{"RC_YAW", &yawChannel},
 	{"RC_MODE", &modeChannel},
 	// wifi
 	{"WIFI_MODE", &wifiMode},
 	{"WIFI_PORT_LOC", &udpLocalPort},
 	{"WIFI_PORT_REM", &udpRemotePort},
 	{"WIFI_LONG_RANGE", &wifiLongRange},
 	// espnow
 	{"ESPNOW_CHANNEL", &espnowChannel},
 	// mavlink
 	{"MAV_SYS_ID", &mavlinkSysId},
 	{"MAV_RATE_SLOW", &telemetrySlow.rate},
 	{"MAV_RATE_FAST", &telemetryFast.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");
 	// Read parameters from storage
 	for (auto &parameter : parameters) {
 		if (!storage.isKey(parameter.name)) {
 			storage.putFloat(parameter.name, parameter.getValue()); // store default value
 		}
 		parameter.setValue(storage.getFloat(parameter.name, 0));
 		parameter.cache = parameter.getValue();
 	}
 }
 int parametersCount() {
 	return sizeof(parameters) / sizeof(parameters[0]);
 }
 const char *getParameterName(int index) {
 	if (index < 0 || index >= parametersCount()) return "";
 	return parameters[index].name;
 }
 float getParameter(int index) {
 	if (index < 0 || index >= parametersCount()) return NAN;
 	return parameters[index].getValue();
 }
 float getParameter(const char *name) {
 	for (auto &parameter : parameters) {
 		if (strcasecmp(parameter.name, name) == 0) {
 			return parameter.getValue();
 		}
 	}
 	return NAN;
 }
 bool setParameter(const char *name, const float value) {
 	for (auto &parameter : parameters) {
 		if (strcasecmp(parameter.name, name) == 0) {
 			if (parameter.integer && !isfinite(value)) return false; // can't set integer to NaN or Inf
 			parameter.setValue(value);
 			if (parameter.callback) parameter.callback();
 			return true;
 		}
 	}
 	return false;
 }
 void syncParameters() {
 	static Rate rate(1);
 	if (!rate) return; // sync once per second
 	if (motorsActive()) return; // don't use flash while flying, it may cause a delay
 	for (auto &parameter : parameters) {
 		if (parameter.getValue() == parameter.cache) continue; // no change
 		if (isnan(parameter.getValue()) && isnan(parameter.cache)) continue; // both are NAN
 		storage.putFloat(parameter.name, parameter.getValue());
 		parameter.cache = parameter.getValue(); // update cache
 	}
 }
 void printParameters() {
 	for (auto &parameter : parameters) {
 		print("%s = %g\n", parameter.name, parameter.getValue());
 	}
 }
 void resetParameters() {
 	storage.clear();
 	ESP.restart();
 }
@@ -0,0 +1,143 @@
 // Copyright (c) 2024 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // Parameters storage in flash memory
 #include <Preferences.h>
 extern float channelZero[16];
 extern float channelMax[16];
 extern float rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
 Preferences storage;
 struct Parameter {
 	const char *name; // max length is 16
 	float *variable;
 	float value; // cache
 };
 Parameter parameters[] = {
 	// control
 	{"ROLLRATE_P", &rollRatePID.p},
 	{"ROLLRATE_I", &rollRatePID.i},
 	{"ROLLRATE_D", &rollRatePID.d},
 	{"ROLLRATE_I_LIM", &rollRatePID.windup},
 	{"PITCHRATE_P", &pitchRatePID.p},
 	{"PITCHRATE_I", &pitchRatePID.i},
 	{"PITCHRATE_D", &pitchRatePID.d},
 	{"PITCHRATE_I_LIM", &pitchRatePID.windup},
 	{"YAWRATE_P", &yawRatePID.p},
 	{"YAWRATE_I", &yawRatePID.i},
 	{"YAWRATE_D", &yawRatePID.d},
 	{"ROLL_P", &rollPID.p},
 	{"ROLL_I", &rollPID.i},
 	{"ROLL_D", &rollPID.d},
 	{"PITCH_P", &pitchPID.p},
 	{"PITCH_I", &pitchPID.i},
 	{"PITCH_D", &pitchPID.d},
 	{"YAW_P", &yawPID.p},
 	{"PITCHRATE_MAX", &maxRate.y},
 	{"ROLLRATE_MAX", &maxRate.x},
 	{"YAWRATE_MAX", &maxRate.z},
 	{"TILT_MAX", &tiltMax},
 	// imu
 	{"ACC_BIAS_X", &accBias.x},
 	{"ACC_BIAS_Y", &accBias.y},
 	{"ACC_BIAS_Z", &accBias.z},
 	{"ACC_SCALE_X", &accScale.x},
 	{"ACC_SCALE_Y", &accScale.y},
 	{"ACC_SCALE_Z", &accScale.z},
 	// rc
 	{"RC_ZERO_0", &channelZero[0]},
 	{"RC_ZERO_1", &channelZero[1]},
 	{"RC_ZERO_2", &channelZero[2]},
 	{"RC_ZERO_3", &channelZero[3]},
 	{"RC_ZERO_4", &channelZero[4]},
 	{"RC_ZERO_5", &channelZero[5]},
 	{"RC_ZERO_6", &channelZero[6]},
 	{"RC_ZERO_7", &channelZero[7]},
 	{"RC_MAX_0", &channelMax[0]},
 	{"RC_MAX_1", &channelMax[1]},
 	{"RC_MAX_2", &channelMax[2]},
 	{"RC_MAX_3", &channelMax[3]},
 	{"RC_MAX_4", &channelMax[4]},
 	{"RC_MAX_5", &channelMax[5]},
 	{"RC_MAX_6", &channelMax[6]},
 	{"RC_MAX_7", &channelMax[7]},
 	{"RC_ROLL", &rollChannel},
 	{"RC_PITCH", &pitchChannel},
 	{"RC_THROTTLE", &throttleChannel},
 	{"RC_YAW", &yawChannel},
 	{"RC_MODE", &modeChannel},
 };
 void setupParameters() {
 	storage.begin("flix", false);
 	// Read parameters from storage
 	for (auto &parameter : parameters) {
 		if (!storage.isKey(parameter.name)) {
 			storage.putFloat(parameter.name, *parameter.variable);
 		}
 		*parameter.variable = storage.getFloat(parameter.name, *parameter.variable);
 		parameter.value = *parameter.variable;
 	}
 }
 int parametersCount() {
 	return sizeof(parameters) / sizeof(parameters[0]);
 }
 const char *getParameterName(int index) {
 	if (index < 0 || index >= parametersCount()) return "";
 	return parameters[index].name;
 }
 float getParameter(int index) {
 	if (index < 0 || index >= parametersCount()) return NAN;
 	return *parameters[index].variable;
 }
 float getParameter(const char *name) {
 	for (auto &parameter : parameters) {
 		if (strcmp(parameter.name, name) == 0) {
 			return *parameter.variable;
 		}
 	}
 	return NAN;
 }
 bool setParameter(const char *name, const float value) {
 	for (auto &parameter : parameters) {
 		if (strcmp(parameter.name, name) == 0) {
 			*parameter.variable = value;
 			return true;
 		}
 	}
 	return false;
 }
 void syncParameters() {
 	static float lastSync = 0;
 	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 (parameter.value == *parameter.variable) continue;
 		if (isnan(parameter.value) && isnan(*parameter.variable)) continue; // handle NAN != NAN
 		storage.putFloat(parameter.name, *parameter.variable);
 		parameter.value = *parameter.variable;
 	}
 }
 void printParameters() {
 	for (auto &parameter : parameters) {
 		print("%s = %g\n", parameter.name, *parameter.variable);
 	}
 }
 void resetParameters() {
 	storage.clear();
 	ESP.restart();
 }
@@ -5,8 +5,6 @@
 #pragma once
 #include "Arduino.h"
 #include "flix.h"
 #include "lpf.h"
 class PID {
@@ -1,28 +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);
 }
@@ -5,7 +5,6 @@
 #pragma once
 #include <Arduino.h>
 #include "vector.h"
 class Quaternion : public Printable {
@@ -1,105 +0,0 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // Work with the RC receiver
 #include <SBUS.h>
 #include "util.h"
 static SBUS rc(Serial1);
 int rcRxPin = -1; // -1 means disabled
 uint16_t channels[16]; // raw rc channels
 int channelZero[16]; // calibration zero values
 int channelMax[16]; // calibration max values
 float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
 float controlMode = 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);
 }
 bool readRC() {
 	if (rcRxPin < 0) return false;
 	if (rc.read()) {
 		SBUSData data = rc.data();
 		for (int i = 0; i < 16; i++) channels[i] = data.ch[i]; // copy channels data
 		normalizeRC();
 		controlTime = t;
 		return true;
 	}
 	return false;
 }
 void normalizeRC() {
 	float controls[16];
 	for (int i = 0; i < 16; i++) {
 		controls[i] = mapf(channels[i], channelZero[i], channelMax[i], 0, 1);
 	}
 	// Update control values
 	controlRoll = rollChannel < 0 ? 0 : controls[rollChannel];
 	controlPitch = pitchChannel < 0 ? 0 : controls[pitchChannel];
 	controlYaw = yawChannel < 0 ? 0 : controls[yawChannel];
 	controlThrottle = throttleChannel < 0 ? 0 : controls[throttleChannel];
 	controlMode = modeChannel < 0 ? NAN : controls[modeChannel]; // mode control is ineffective if not mapped
 }
 void calibrateRC() {
 	if (rcRxPin < 0) {
 		print("RC_RX_PIN = %d, set the RC pin!\n", rcRxPin);
 		return;
 	}
 	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(&throttleChannel, zero, _, "3/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
 	calibrateRCChannel(NULL, _, center, "4/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
 	calibrateRCChannel(&yawChannel, center, _, "5/8 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(&rollChannel, zero, _, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
 	calibrateRCChannel(&modeChannel, zero, _, "8/8 Put mode switch to max [3 sec]\n");
 	printRCCalibration();
 }
 void calibrateRCChannel(int *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
 	memcpy(out, channels, sizeof(channels));
 	if (channel == NULL) return; // no channel to calibrate
 	// Find channel that changed the most between in and out
 	int ch = -1, diff = 0;
 	for (int i = 0; i < 16; i++) {
 		if (abs(out[i] - in[i]) > diff) {
 			ch = i;
 			diff = abs(out[i] - in[i]);
 		}
 	}
 	if (ch >= 0 && diff > 10) { // difference threshold is 10
 		*channel = ch;
 		channelZero[ch] = in[ch];
 		channelMax[ch] = out[ch];
 	} else {
 		*channel = -1;
 	}
 }
 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("Pitch     %-7d%-7d%-7d\n", pitchChannel, pitchChannel < 0 ? 0 : channelZero[pitchChannel], pitchChannel < 0 ? 0 : channelMax[pitchChannel]);
 	print("Yaw       %-7d%-7d%-7d\n", yawChannel, yawChannel < 0 ? 0 : channelZero[yawChannel], yawChannel < 0 ? 0 : channelMax[yawChannel]);
 	print("Throttle  %-7d%-7d%-7d\n", throttleChannel, throttleChannel < 0 ? 0 : channelZero[throttleChannel], throttleChannel < 0 ? 0 : channelMax[throttleChannel]);
 	print("Mode      %-7d%-7d%-7d\n", modeChannel, modeChannel < 0 ? 0 : channelZero[modeChannel], modeChannel < 0 ? 0 : channelMax[modeChannel]);
 }
@@ -0,0 +1,96 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // Work with the RC receiver
 #include <SBUS.h>
 #include "util.h"
 SBUS rc(Serial2); // NOTE: Use RC(Serial2, 16, 17) if you use the old UART2 pins
 uint16_t channels[16]; // raw rc channels
 float controlTime; // time of the last controls update
 float channelZero[16]; // calibration zero values
 float channelMax[16]; // calibration max values
 // Channels mapping (using float to store in parameters):
 float rollChannel = NAN, pitchChannel = NAN, throttleChannel = NAN, yawChannel = NAN, modeChannel = NAN;
 void setupRC() {
 	print("Setup RC\n");
 	rc.begin();
 }
 bool readRC() {
 	if (rc.read()) {
 		SBUSData data = rc.data();
 		for (int i = 0; i < 16; i++) channels[i] = data.ch[i]; // copy channels data
 		normalizeRC();
 		controlTime = t;
 		return true;
 	}
 	return false;
 }
 void normalizeRC() {
 	float controls[16];
 	for (int i = 0; i < 16; i++) {
 		controls[i] = mapf(channels[i], channelZero[i], channelMax[i], 0, 1);
 	}
 	// Update control values
 	controlRoll = rollChannel >= 0 ? controls[(int)rollChannel] : NAN;
 	controlPitch = pitchChannel >= 0 ? controls[(int)pitchChannel] : NAN;
 	controlYaw = yawChannel >= 0 ? controls[(int)yawChannel] : NAN;
 	controlThrottle = throttleChannel >= 0 ? controls[(int)throttleChannel] : NAN;
 	controlMode = modeChannel >= 0 ? controls[(int)modeChannel] : NAN;
 }
 void calibrateRC() {
 	uint16_t zero[16];
 	uint16_t center[16];
 	uint16_t max[16];
 	print("1/8 Calibrating RC: put all switches to default positions [3 sec]\n");
 	pause(3);
 	calibrateRCChannel(NULL, zero, zero, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
 	calibrateRCChannel(NULL, center, center, "3/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
 	calibrateRCChannel(&throttleChannel, zero, max, "4/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
 	calibrateRCChannel(&yawChannel, center, max, "5/8 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
 	calibrateRCChannel(&pitchChannel, zero, max, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
 	calibrateRCChannel(&rollChannel, zero, max, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
 	calibrateRCChannel(&modeChannel, zero, max, "8/8 Put mode switch to max [3 sec]\n");
 	printRCCalibration();
 }
 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
 	memcpy(out, channels, sizeof(channels));
 	if (channel == NULL) return; // no channel to calibrate
 	// Find channel that changed the most between in and out
 	int ch = -1, diff = 0;
 	for (int i = 0; i < 16; i++) {
 		if (abs(out[i] - in[i]) > diff) {
 			ch = i;
 			diff = abs(out[i] - in[i]);
 		}
 	}
 	if (ch >= 0 && diff > 10) { // difference threshold is 10
 		*channel = ch;
 		channelZero[ch] = in[ch];
 		channelMax[ch] = out[ch];
 	} else {
 		*channel = NAN;
 	}
 }
 void printRCCalibration() {
 	print("Control   Ch     Zero   Max\n");
 	print("Roll      %-7g%-7g%-7g\n", rollChannel, rollChannel >= 0 ? channelZero[(int)rollChannel] : NAN, rollChannel >= 0 ? channelMax[(int)rollChannel] : NAN);
 	print("Pitch     %-7g%-7g%-7g\n", pitchChannel, pitchChannel >= 0 ? channelZero[(int)pitchChannel] : NAN, pitchChannel >= 0 ? channelMax[(int)pitchChannel] : NAN);
 	print("Yaw       %-7g%-7g%-7g\n", yawChannel, yawChannel >= 0 ? channelZero[(int)yawChannel] : NAN, yawChannel >= 0 ? channelMax[(int)yawChannel] : NAN);
 	print("Throttle  %-7g%-7g%-7g\n", throttleChannel, throttleChannel >= 0 ? channelZero[(int)throttleChannel] : NAN, throttleChannel >= 0 ? channelMax[(int)throttleChannel] : NAN);
 	print("Mode      %-7g%-7g%-7g\n", modeChannel, modeChannel >= 0 ? channelZero[(int)modeChannel] : NAN, modeChannel >= 0 ? channelMax[(int)modeChannel] : NAN);
 }
@@ -3,15 +3,11 @@
 // Fail-safe functions
-#include "config.h"
+#define RC_LOSS_TIMEOUT 1
-#include "flix.h"
+#define DESCEND_TIME 10
 #include "util.h"
 extern float controlTime;
-extern const int AUTO, STAB;
+extern float controlRoll, controlPitch, controlThrottle, controlYaw;
 float rcLossTimeout = 1;
 float descendTime = 10;
 void failsafe() {
 	rcLossFailsafe();
@@ -20,8 +16,9 @@ void failsafe() {
 // RC loss failsafe
 void rcLossFailsafe() {
 	if (controlTime == 0) return; // no RC at all
 	if (!armed) return;
-	if (t - controlTime > rcLossTimeout) {
+	if (t - controlTime > RC_LOSS_TIMEOUT) {
 		descend();
 	}
 }
@@ -30,7 +27,7 @@ void rcLossFailsafe() {
 void descend() {
 	mode = AUTO;
 	attitudeTarget = Quaternion();
-	thrustTarget -= dt / descendTime;
+	thrustTarget -= dt / DESCEND_TIME;
 	if (thrustTarget < 0) {
 		thrustTarget = 0;
 		armed = false;
@@ -41,8 +38,8 @@ void descend() {
 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
+		// controls changed
-		if (mode == AUTO && invalid(controlMode)) mode = STAB; // regain control by the pilot
+		if (mode == AUTO) mode = STAB; // regain control by the pilot
 	}
 	roll = controlRoll;
 	pitch = controlPitch;
@@ -3,11 +3,6 @@
 // Time related functions
 #include "Arduino.h"
 #include "flix.h"
 float t = NAN; // current time, s
 float dt; // time delta with the previous step, s
 float loopRate; // Hz
 void step() {
@@ -6,25 +6,30 @@
 #pragma once
 #include <math.h>
-#include <ESP32_NOW_Serial.h>
+#include <soc/soc.h>
-#include "flix.h"
+#include <soc/rtc_cntl_reg.h>
 const float ONE_G = 9.80665;
 extern float t;
-inline float mapf(float x, float in_min, float in_max, float out_min, float out_max) {
+float mapf(long x, long in_min, long in_max, float out_min, float out_max) {
 	return (float)(x - in_min) * (out_max - out_min) / (float)(in_max - in_min) + out_min;
 }
 float mapff(float x, float in_min, float in_max, float out_min, float out_max) {
 	return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
 }
-inline bool invalid(float x) {
+bool invalid(float x) {
 	return !isfinite(x);
 }
-inline bool valid(float x) {
+bool valid(float x) {
 	return isfinite(x);
 }
 // Wrap angle to [-PI, PI)
-inline float wrapAngle(float angle) {
+float wrapAngle(float angle) {
 	angle = fmodf(angle, 2 * PI);
 	if (angle > PI) {
 		angle -= 2 * PI;
@@ -34,57 +39,35 @@ inline float wrapAngle(float angle) {
 	return angle;
 }
 // Disable reset on low voltage
 void disableBrownOut() {
 	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA);
 }
 // Trim and split string by spaces
-inline void splitString(String& str, String& token0, String& token1, String& token2) {
+void splitString(String& str, String& token0, String& token1, String& token2) {
 	str.trim();
 	if (str.isEmpty()) return;
 	char chars[str.length() + 1];
 	str.toCharArray(chars, str.length() + 1);
 	token0 = strtok(chars, " ");
-	token1 = strtok(NULL, " ");
+	token1 = strtok(NULL, " "); // String(NULL) creates empty string
 	token2 = strtok(NULL, "");
 	if (token1.c_str() == NULL) token1 = "";
 	if (token2.c_str() == NULL) token2 = "";
 }
 // Simplified ESP-NOW Serial without tx buffering and resends
 class ESPNOWSerial : public ESP_NOW_Serial_Class {
 public:
 	using ESP_NOW_Serial_Class::ESP_NOW_Serial_Class;
 	void onSent(bool success) override {} // disable resends
 	size_t write(const uint8_t *data, size_t len) override {
 		return ESP_NOW_Peer::send(data, len); // pure send without buffering
 	}
 };
 // Rate limiter
 class Rate {
 public:
 	float rate;
 	float last = 0;
 	Rate(float rate) : rate(rate) {}
 	operator bool() {
 		if (t - last >= 1 / rate) {
 			last = t;
 			return true;
 		}
 		return false;
 	}
 };
 // Delay filter for boolean signals - ensures the signal is on for at least 'delay' seconds
 class Delay {
 public:
 	float delay;
 	float start = NAN;
 	Delay(float delay) : delay(delay) {}
 	bool update(bool on) {
 		if (!on) {
 			start = NAN;
 			return false;
-		} else if (isnan(start)) {
+		}
 		if (isnan(start)) {
 			start = t;
 		}
 		return t - start >= delay;
@@ -5,8 +5,6 @@
 #pragma once
 #include <Arduino.h>
 class Vector : public Printable {
 public:
 	float x, y, z;
@@ -37,6 +35,7 @@ public:
 		z = NAN;
 	}
 	float norm() const {
 		return sqrt(x * x + y * y + z * z);
 	}
@@ -107,23 +106,10 @@ public:
 	}
 	static Vector rotationVectorBetween(const Vector& a, const Vector& b) {
 		float an = a.norm();
 		float bn = b.norm();
 		if (an < 1e-6 || bn < 1e-6) {
 			return Vector(0, 0, 0);
 		}
 		Vector direction = cross(a, b);
-		if (direction.norm() < 1e-6) { // vectors are parallel
+		if (direction.zero()) {
-			if (dot(a, b) > 0) { // same direction
+			// vectors are opposite, return any perpendicular vector
-				return Vector(0, 0, 0);
+			return cross(a, Vector(1, 0, 0));
 			}
 			// opposite direction
 			Vector perp = cross(a, Vector(1, 0, 0));
 			if (perp.norm() < 1e-6) {
 				perp = cross(a, Vector(0, 1, 0));
 			}
 			perp.normalize();
 			return perp * PI;
 		}
 		direction.normalize();
 		float angle = angleBetween(a, b);
@@ -138,5 +124,5 @@ public:
 	}
 };
-inline Vector operator * (const float a, const Vector& b) { return b * a; }
+Vector operator * (const float a, const Vector& b) { return b * a; }
-inline Vector operator + (const float a, const Vector& b) { return b + a; }
+Vector operator + (const float a, const Vector& b) { return b + a; }
@@ -1,132 +0,0 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // Wi-Fi and ESP-NOW communication
 #include <WiFi.h>
 #include <WiFiAP.h>
 #include <WiFiUdp.h>
 #include <MacAddress.h>
 #include <ESP32_NOW_Serial.h>
 #include <Preferences.h>
 #include "config.h"
 #include "flix.h"
 #include "util.h"
 extern Preferences storage; // use the main preferences storage
 extern bool mavlinkConnected;
 extern const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
 int wifiMode = W_AP;
 int wifiLongRange = 0;
 int udpLocalPort = 14550;
 int udpRemotePort = 14550;
 static IPAddress udpRemoteIP = "255.255.255.255";
 static WiFiUDP udp;
 static ESPNOWSerial espnow(NULL, 0, WIFI_IF_AP);
 static ESPNOWSerial espnowBroadcast(ESP_NOW.BROADCAST_ADDR, 0, WIFI_IF_AP);
 int espnowChannel = 6;
 void setupWiFi() {
 	print("Setup Wi-Fi\n");
 	WiFi.enableLongRange(wifiLongRange);
 	if (wifiMode == W_AP) {
 		WiFi.softAP(storage.getString("WIFI_AP_SSID", "flix").c_str(), storage.getString("WIFI_AP_PASS", "flixwifi").c_str());
 		udp.begin(udpLocalPort);
 	} else if (wifiMode == W_STA) {
 		WiFi.begin(storage.getString("WIFI_STA_SSID", "").c_str(), storage.getString("WIFI_STA_PASS", "").c_str());
 		udp.begin(udpLocalPort);
 	} else if (wifiMode == W_ESPNOW) {
 		WiFi.mode(WIFI_AP);
 		WiFi.setChannel(espnowChannel);
 		espnow.addr(MacAddress(storage.getString("ESPNOW_PEER_MAC", "FF:FF:FF:FF:FF:FF").c_str()));
 		String key = storage.getString("ESPNOW_PEER_KEY", "");
 		espnow.setKey(key.isEmpty() ? nullptr : (const uint8_t *)key.c_str());
 		espnow.begin();
 		espnowBroadcast.begin();
 	}
 	WiFi.setSleep(false); // disable power save
 }
 void sendWiFi(const uint8_t *buf, int len) {
 	if (espnow) {
 		espnow.write(buf, len);
 		static Rate discovery(2);
 		if (discovery) espnowBroadcast.write((const uint8_t *)"flix", 4); // broadcast message to help finding this device
 		return;
 	}
 	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return;
 	udp.beginPacket(udpRemoteIP, udpRemotePort);
 	udp.write(buf, len);
 	udp.endPacket();
 }
 int receiveWiFi(uint8_t *buf, int len) {
 	if (espnow) {
 		return espnow.read(buf, len);
 	}
 	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return 0;
 	udp.parsePacket();
 	if (udp.remoteIP()) udpRemoteIP = udp.remoteIP();
 	return udp.read(buf, len);
 }
 void printWiFiInfo() {
 	if (espnow) {
 		print("Mode: ESP-NOW\n");
 		print("ESP-NOW version: %d\n", ESP_NOW.getVersion());
 		print("Max packet size: %d\n", ESP_NOW.getMaxDataLen());
 		print("MAC: %s\n", WiFi.softAPmacAddress().c_str());
 		print("Peer MAC: %s\n", MacAddress(espnow.addr()).toString().c_str());
 		print("Encrypted: %d\n", espnow.isEncrypted());
 		print("Channel: %d\n", espnow.getChannel());
 	} else if (WiFi.getMode() == WIFI_MODE_AP) {
 		print("Mode: Access Point (AP)\n");
 		print("MAC: %s\n", WiFi.softAPmacAddress().c_str());
 		print("SSID: %s\n", WiFi.softAPSSID().c_str());
 		print("Password: ***\n");
 		print("Channel: %d\n", WiFi.channel());
 		print("Clients: %d\n", WiFi.softAPgetStationNum());
 		print("IP: %s\n", WiFi.softAPIP().toString().c_str());
 		print("Remote IP: %s\n", udpRemoteIP.toString().c_str());
 	} else if (WiFi.getMode() == WIFI_MODE_STA) {
 		print("Mode: Client (STA)\n");
 		print("Connected: %d\n", WiFi.isConnected());
 		print("MAC: %s\n", WiFi.macAddress().c_str());
 		print("SSID: %s\n", WiFi.SSID().c_str());
 		print("Password: ***\n");
 		print("Channel: %d\n", WiFi.channel());
 		print("RSSI: %d dBm\n", WiFi.RSSI());
 		print("IP: %s\n", WiFi.localIP().toString().c_str());
 		print("Remote IP: %s\n", udpRemoteIP.toString().c_str());
 	} else {
 		print("Mode: Disabled\n");
 	}
 	print("MAVLink connected: %d\n", mavlinkConnected);
 }
 void configWiFi(int mode, const char *first, const char *second) {
 	MacAddress mac;
 	if (mode == W_AP && strlen(first) > 0 && strlen(second) >= 8) {
 		storage.putString("WIFI_AP_SSID", first);
 		storage.putString("WIFI_AP_PASS", second);
 	} else if (mode == W_STA && strlen(first) > 0 && strlen(second) >= 8) {
 		storage.putString("WIFI_STA_SSID", first);
 		storage.putString("WIFI_STA_PASS", second);
 	} else if (mode == W_ESPNOW && mac.fromString(first)) {
 		storage.putString("ESPNOW_PEER_MAC", first);
 		storage.putString("ESPNOW_PEER_KEY", strlen(second) == ESP_NOW_KEY_LEN ? second : "");
 	} else {
 		print("Invalid configuration\n");
 		return;
 	}
 	print("✓ Reboot to apply new settings\n");
 }
@@ -0,0 +1,38 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 // Wi-Fi support
 #if WIFI_ENABLED
 #include <WiFi.h>
 #include <WiFiAP.h>
 #include <WiFiUdp.h>
 #define WIFI_SSID "flix"
 #define WIFI_PASSWORD "flixwifi"
 #define WIFI_UDP_PORT 14550
 #define WIFI_UDP_REMOTE_PORT 14550
 #define WIFI_UDP_REMOTE_ADDR "255.255.255.255"
 WiFiUDP udp;
 void setupWiFi() {
 	print("Setup Wi-Fi\n");
 	WiFi.softAP(WIFI_SSID, WIFI_PASSWORD);
 	udp.begin(WIFI_UDP_PORT);
 }
 void sendWiFi(const uint8_t *buf, int len) {
 	if (WiFi.softAPIP() == IPAddress(0, 0, 0, 0) && WiFi.status() != WL_CONNECTED) return;
 	udp.beginPacket(udp.remoteIP() ? udp.remoteIP() : WIFI_UDP_REMOTE_ADDR, WIFI_UDP_REMOTE_PORT);
 	udp.write(buf, len);
 	udp.endPacket();
 }
 int receiveWiFi(uint8_t *buf, int len) {
 	udp.parsePacket();
 	return udp.read(buf, len);
 }
 #endif
@@ -21,8 +21,6 @@
 #define degrees(rad) ((rad)*RAD_TO_DEG)
 #define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
 template<typename T> T max(T a, T b) { return a > b ? a : b; }
 template<typename T> T min(T a, T b) { return a < b ? a : b; }
 long map(long x, long in_min, long in_max, long out_min, long out_max) {
 	const long run = in_max - in_min;
@@ -151,7 +149,7 @@ public:
 	void setRxInvert(bool invert) {};
 };
-HardwareSerial Serial, Serial1, Serial2;
+HardwareSerial Serial, Serial2;
 class EspClass {
 public:
@@ -167,9 +165,6 @@ void delay(uint32_t ms) {
 bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution) { return true; }
 bool ledcWrite(uint8_t pin, uint32_t duty) { return true; }
 uint32_t ledcChangeFrequency(uint8_t pin, uint32_t freq, uint8_t resolution) { return freq; }
 int8_t digitalPinToAnalogChannel(uint8_t pin) { return -1; }
 uint32_t analogReadMilliVolts(uint8_t pin) { return 0; }
 unsigned long __micros;
 unsigned long __resetTime = 0;
@@ -10,23 +10,9 @@ list(APPEND CMAKE_CXX_FLAGS "${GAZEBO_CXX_FLAGS}")
 set(FLIX_SOURCE_DIR ../flix)
 include_directories(${FLIX_SOURCE_DIR})
 set(FLIX_SOURCE_DIR ../flix)
 include_directories(${FLIX_SOURCE_DIR})
 set(FLIX_SOURCES
  ${FLIX_SOURCE_DIR}/cli.cpp
  ${FLIX_SOURCE_DIR}/control.cpp
  ${FLIX_SOURCE_DIR}/estimate.cpp
  ${FLIX_SOURCE_DIR}/safety.cpp
  ${FLIX_SOURCE_DIR}/log.cpp
  ${FLIX_SOURCE_DIR}/mavlink.cpp
  ${FLIX_SOURCE_DIR}/motors.cpp
  ${FLIX_SOURCE_DIR}/parameters.cpp
  ${FLIX_SOURCE_DIR}/rc.cpp
  ${FLIX_SOURCE_DIR}/time.cpp
 )
 set(CMAKE_BUILD_TYPE RelWithDebInfo)
-add_library(flix SHARED simulator.cpp ${FLIX_SOURCES})
+add_library(flix SHARED simulator.cpp)
 target_link_libraries(flix ${GAZEBO_LIBRARIES} ${SDL2_LIBRARIES})
 target_include_directories(flix PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 target_compile_options(flix PRIVATE -Wno-address-of-packed-member) # disable unneeded mavlink warnings
@@ -1,12 +0,0 @@
 // Dummy file for the simulator
 class ESP_NOW_Peer {
 protected:
 	size_t send(const uint8_t *data, int len) { return 0; }
 };
 class ESP_NOW_Serial_Class : public ESP_NOW_Peer {
 public:
 	virtual void onSent(bool success) {};
 	virtual size_t write(const uint8_t *data, size_t len) { return 0; };
 };
@@ -1,99 +1,15 @@
-# Simulation
+# Gazebo Simulation
-The Flix drone simulator is based on Gazebo 11 and runs the firmware code in virtual physical environment.
+<img src="../docs/img/simulator.png" width=500 alt="Flix simulator">
-Gazebo 11 works on **Ubuntu 20.04** and used to work on macOS. However, on the recent macOS versions it seems to be broken, so Ubuntu 20.04 is recommended.
+## Building and running
-<img src="../docs/img/simulator1.png" width=600 alt="Flix simulator running on macOS">
+See [building and running instructions](../docs/usage.md#simulation).
 ## Installation
 1. Clone the Flix repository using it:
   ```bash
   git clone https://github.com/okalachev/flix.git && cd flix
   ```
 2. Install Arduino CLI:
   ```bash
   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
   ```
 3. Install Gazebo 11:
   ```bash
   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
   ```
   Set up your Gazebo environment variables:
   ```bash
   echo "source /usr/share/gazebo/setup.sh" >> ~/.bashrc
   source ~/.bashrc
   ```
 4. Install SDL2 and other dependencies:
   ```bash
   sudo apt-get update && sudo apt-get install build-essential libsdl2-dev
   ```
 5. 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
   ```
 6. Run the simulation:
   ```bash
   make simulator
   ```
 ## Usage
 Just like the real drone, the simulator can be controlled using a USB remote control or a smartphone.
 ### 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!
 > [!TIP]
 > Decrease `CTL_TILT_MAX` parameter when flying using the smartphone to make the controls less sensitive.
 ### 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. Use the USB remote control to fly the drone!
 ### Piloting
 To start the flight, arm the drone moving the throttle stick to the bottom right position:
 <img src="../docs/img/arming.svg" width="150">
 To disarm, move the throttle stick to the bottom left position:
 <img src="../docs/img/disarming.svg" width="150">
 See other piloting and usage details in general [usage article](../docs/usage.md).
 ## Code structure
-Flix simulator consists of the following components:
+Flix simulator is based on [Gazebo Classic](https://classic.gazebosim.org) and consists of the following components:
-* Physical model of the drone in Gazebo format: [`models/flix/flix.sdf`](models/flix/flix.sdf).
+* Physical model of the drone: [`models/flix/flix.sdf`](models/flix/flix.sdf).
 * Plugin for Gazebo: [`simulator.cpp`](simulator.cpp). The plugin is attached to the physical model. It receives stick positions from the controller, gets the data from the virtual sensors, and then passes this data to the Arduino code.
-* Arduino emulation: [`Arduino.h`](Arduino.h). This file contains partial implementation of the Arduino API, that is working within Gazebo plugin environment.
+* Arduino imitation: [`Arduino.h`](Arduino.h). This file contains partial implementation of the Arduino API, that is working within Gazebo plugin environment.
@@ -13,7 +13,7 @@ class SBUS {
 public:
 	SBUS(HardwareSerial& bus, const bool inv = true) {};
 	SBUS(HardwareSerial& bus, const int8_t rxpin, const int8_t txpin, const bool inv = true) {};
-	void begin(int rxpin = -1, int txpin = -1, bool inv = true, bool fast = false) {};
+	void begin() {};
 	bool read() { return joystickInit(); };
 	SBUSData data() {
 		SBUSData data;
@@ -9,47 +9,43 @@
 #include "quaternion.h"
 #include "Arduino.h"
 #include "wifi.h"
 #include "lpf.h"
-extern float t, dt;
+#define WIFI_ENABLED 1
 extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
 extern Vector rates;
 extern Quaternion attitude;
 extern bool landed;
 extern float motors[4];
-Vector gyro, acc, imuRotation;
+float t = NAN;
-Vector accBias, gyroBias, accScale(1, 1, 1);
+float dt;
-LowPassFilter<Vector> gyroBiasFilter(0);
+float motors[4];
 float controlRoll, controlPitch, controlYaw, controlThrottle = NAN;
 float controlMode = NAN;
 Vector acc;
 Vector gyro;
 Vector rates;
 Quaternion attitude;
 bool landed;
 // declarations
 void step();
 void computeLoopRate();
 void applyGyro();
 void applyAcc();
 void applyLevel();
 void control();
 void interpretControls();
 void controlAttitude();
 void controlRates();
 void controlTorque();
 void desaturate(float& a, float& b, float& c, float& d);
 const char* getModeName();
 void sendMotors();
 int getDutyCycle(float value);
 bool motorsActive();
 void testMotor(int n);
 void print(const char* format, ...);
 void pause(float duration);
 void doCommand(String str, bool echo);
 void handleInput();
 void setupRC();
 void normalizeRC();
 void calibrateRC();
-void calibrateRCChannel(int*, uint16_t[16], uint16_t[16], const char*);
+void calibrateRCChannel(float *channel, uint16_t zero[16], uint16_t max[16], const char *str);
 void printRCCalibration();
-void printLogHeader();
+void dumpLog();
 void printLogData();
 void processMavlink();
 void sendMavlink();
 void sendMessage(const void *msg);
@@ -58,7 +54,6 @@ void handleMavlink(const void *_msg);
 void mavlinkPrint(const char* str);
 void sendMavlinkPrint();
 inline Quaternion fluToFrd(const Quaternion &q);
 void setupPower();
 void failsafe();
 void rcLossFailsafe();
 void descend();
@@ -77,5 +72,4 @@ void calibrateGyro() { print("Skip gyro calibrating\n"); };
 void calibrateAccel() { print("Skip accel calibrating\n"); };
 void printIMUCalibration() { print("cal: N/A\n"); };
 void printIMUInfo() {};
-void printWiFiInfo() {};
+Vector accBias, gyroBias, accScale(1, 1, 1);
 void configWiFi(bool, const char*, const char*) { print("Skip WiFi config\n"); };
@@ -18,6 +18,18 @@
 #include "Arduino.h"
 #include "flix.h"
 #include "cli.ino"
 #include "control.ino"
 #include "estimate.ino"
 #include "safety.ino"
 #include "log.ino"
 #include "lpf.h"
 #include "mavlink.ino"
 #include "motors.ino"
 #include "parameters.ino"
 #include "rc.ino"
 #include "time.ino"
 using ignition::math::Vector3d;
 using namespace gazebo;
 using namespace std;
@@ -60,8 +72,6 @@ public:
 		gyro = Vector(imu->AngularVelocity().X(), imu->AngularVelocity().Y(), imu->AngularVelocity().Z());
 		acc = this->accFilter.update(Vector(imu->LinearAcceleration().X(), imu->LinearAcceleration().Y(), imu->LinearAcceleration().Z()));
 		voltage = 4.2f; // dummy voltage value
 		readRC();
 		estimate();
@@ -1,3 +1,4 @@
 // Dummy file to make it possible to compile simulator with Flix' util.h
 #define WRITE_PERI_REG(addr, val) {}
 #define REG_CLR_BIT(_r, _b) {}
--- a/Show More
+++ b/Show More
		`@@ -1,2 +0,0 @@`
			`<!-- markdownlint-disable MD041 -->`
			`Build instructions are moved to [usage article](usage.md).`