Fix mavlink disconnection in pauses in cli commands

Implement pause function that proceeds processing mavlink. Use temporal workaround for simulation, as micros function gives the same result on the same simulation step.
Use natural order of ino files includes in simulation
2026-01-12 05:57:52 +00:00 · 2025-02-28 19:25:41 +03:00 · 2025-02-28 19:06:58 +03:00 · 2025-02-28 03:17:09 +03:00 · 2025-02-28 00:51:16 +03:00 · 2025-02-26 01:08:36 +03:00
105 changed files with 7319 additions and 408 deletions
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -5,6 +5,7 @@ on:
    branches: [ '*' ]
  pull_request:
    branches: [ master ]
+  workflow_dispatch:

 jobs:
  build_linux:
@@ -45,7 +46,7 @@ jobs:
      run: python3 tools/check_c_cpp_properties.py

  build_simulator:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
    steps:
    - name: Install Arduino CLI
      uses: arduino/setup-arduino-cli@v1.1.1
@@ -62,22 +63,23 @@ jobs:
        path: gazebo/build/*.so
        retention-days: 1

-#  build_simulator_macos:
-#    runs-on: macos-latest
-#    steps:
-#    - name: Install Arduino CLI
-#      run: brew install arduino-cli
-#    - uses: actions/checkout@v4
-#    - name: Clean up python binaries # Workaround for https://github.com/actions/setup-python/issues/577
-#      run: |
-#        rm -f /usr/local/bin/2to3*
-#        rm -f /usr/local/bin/idle3*
-#        rm -f /usr/local/bin/pydoc3*
-#        rm -f /usr/local/bin/python3*
-#        rm -f /usr/local/bin/python3*-config
-#    - name: Install Gazebo
-#      run: brew update && brew tap osrf/simulation && brew install gazebo11
-#    - name: Install SDL2
-#      run: brew install sdl2
-#    - name: Build simulator
-#      run: make build_simulator
+  build_simulator_macos:
+    runs-on: macos-latest
+    if: github.event_name == 'workflow_dispatch'
+    steps:
+    - name: Install Arduino CLI
+      run: brew install arduino-cli
+    - uses: actions/checkout@v4
+    - name: Clean up python binaries # Workaround for https://github.com/actions/setup-python/issues/577
+      run: |
+        rm -f /usr/local/bin/2to3*
+        rm -f /usr/local/bin/idle3*
+        rm -f /usr/local/bin/pydoc3*
+        rm -f /usr/local/bin/python3*
+        rm -f /usr/local/bin/python3*-config
+    - name: Install Gazebo
+      run: brew update && brew tap osrf/simulation && brew install gazebo11
+    - name: Install SDL2
+      run: brew install sdl2
+    - name: Build simulator
+      run: make build_simulator
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -0,0 +1,51 @@
+name: Docs
+
+on:
+  push:
+    branches: [ '*' ]
+  pull_request:
+    branches: [ master ]
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+jobs:
+  markdownlint:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install markdownlint
+      run: npm install -g markdownlint-cli2
+    - name: Run markdownlint
+      run: markdownlint-cli2 "**/*.md"
+
+  build_book:
+    runs-on: ubuntu-latest
+    needs: markdownlint
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install mdBook
+      run: cargo install mdbook --vers 0.4.43 --locked
+    - name: Build book
+      run: cd docs && mdbook build
+    - name: Upload artifact
+      uses: actions/upload-pages-artifact@v3
+      with:
+        path: docs/build
+
+  deploy:
+    if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
+    concurrency:
+      group: "pages"
+      cancel-in-progress: true
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build_book
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4
--- a/.markdownlint.json
+++ b/.markdownlint.json
@@ -0,0 +1,67 @@
+{
+	"MD004": {
+		"style": "asterisk"
+	},
+	"MD010": false,
+	"MD013": false,
+	"MD024": false,
+	"MD033": false,
+	"MD034": false,
+	"MD044": {
+		"html_elements": false,
+		"code_blocks": false,
+		"names": [
+			"FlixPeriph",
+			"Wi-Fi",
+			"STM",
+			"Li-ion",
+			"GitHub",
+			"github.com",
+			"PPM",
+			"PWM",
+			"Futaba",
+			"S.Bus",
+			"C++",
+			"PID",
+			"Arduino IDE",
+			"Arduino",
+			"Arduino Nano",
+			"ESP32",
+			"IMU",
+			"MEMS",
+			"imu.ino",
+			"InvenSense",
+			"MPU-6050",
+			"MPU-9250",
+			"GY-91",
+			"ICM-20948",
+			"Linux",
+			"Windows",
+			"macOS",
+			"iOS",
+			"Android",
+			"Bluetooth",
+			"GPS",
+			"GPIO",
+			"USB",
+			"SPI",
+			"I²C",
+			"UART",
+			"GND",
+			"3V3",
+			"VCC",
+			"SCL",
+			"SDA",
+			"SAO",
+			"AD0",
+			"MOSI",
+			"MISO",
+			"NCS",
+			"MOSFET",
+			"ArduPilot",
+			"Betaflight",
+			"PX4"
+		]
+	},
+	"MD045": false
+}
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -5,18 +5,18 @@
 			"includePath": [
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
-				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/**",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/dio_qspi/include",
 				"~/Arduino/libraries/**",
 				"/usr/include/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -28,9 +28,10 @@
 				"${workspaceFolder}/flix/motors.ino",
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
-				"${workspaceFolder}/flix/wifi.ino"
+				"${workspaceFolder}/flix/wifi.ino",
+				"${workspaceFolder}/flix/parameters.ino"
 			],
-			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2405/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -50,19 +51,19 @@
 			"name": "Mac",
 			"includePath": [
 				"${workspaceFolder}/flix",
-				// "${workspaceFolder}/gazebo",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/include/**",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
+				"${workspaceFolder}/gazebo",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/include/**",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**",
 				"/opt/homebrew/include/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/flix.ino",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
@@ -74,9 +75,10 @@
 				"${workspaceFolder}/flix/motors.ino",
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
-				"${workspaceFolder}/flix/wifi.ino"
+				"${workspaceFolder}/flix/wifi.ino",
+				"${workspaceFolder}/flix/parameters.ino"
 			],
-			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2405/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -98,17 +100,17 @@
 			"includePath": [
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/**",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -120,9 +122,10 @@
 				"${workspaceFolder}/flix/motors.ino",
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
-				"${workspaceFolder}/flix/wifi.ino"
+				"${workspaceFolder}/flix/wifi.ino",
+				"${workspaceFolder}/flix/parameters.ino"
 			],
-			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++.exe",
+			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2405/bin/xtensa-esp32-elf-g++.exe",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
--- a/.vscode/extensions.json
+++ b/.vscode/extensions.json
@@ -2,6 +2,7 @@
 	// See https://go.microsoft.com/fwlink/?LinkId=827846 to learn about workspace recommendations.
 	"recommendations": [
 		"ms-vscode.cpptools",
+		"twxs.cmake",
 		"ms-vscode.cmake-tools",
 		"ms-python.python"
 	],
--- a/4
+++ b/4
@@ -13,10 +13,10 @@ monitor:

 dependencies .dependencies:
 	arduino-cli core update-index --config-file arduino-cli.yaml
-	arduino-cli core install esp32:esp32@3.2.0 --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@3.1.0 --config-file arduino-cli.yaml
 	arduino-cli lib update-index
 	arduino-cli lib install "FlixPeriph"
-	arduino-cli lib install "MAVLink"@2.0.16
+	arduino-cli lib install "MAVLink"@2.0.12
 	touch .dependencies

 gazebo/build cmake: gazebo/CMakeLists.txt
--- a/README.md
+++ b/README.md
@@ -1,7 +1,163 @@
 # Flix

-Minimal **Flix** quadcopter firmware implementation for the [book](https://quadcopter.dev).
+**Flix** (*flight + X*) — making an open source ESP32-based quadcopter from scratch.

-See the full code and documentation in the main branch: https://github.com/okalachev/flix.
+<table>
+  <tr>
+    <td align=center><strong>Version 1.1</strong> (3D-printed frame)</td>
+    <td align=center><strong>Version 0</strong></td>
+  </tr>
+  <tr>
+    <td><img src="docs/img/flix1.1.jpg" width=500 alt="Flix quadcopter"></td>
+    <td><img src="docs/img/flix.jpg" width=500 alt="Flix quadcopter"></td>
+  </tr>
+</table>

-<img src="docs/img/flix1.jpg" width=500 alt="Flix quadcopter">
+## Features
+
+* Simple and clean Arduino based source code.
+* Acro and Stabilized flight using remote control.
+* Precise simulation using Gazebo.
+* [In-RAM logging](docs/log.md).
+* Command line interface through USB port.
+* Wi-Fi support.
+* MAVLink support.
+* Control using mobile phone (with QGroundControl app).
+* Completely 3D-printed frame.
+* Textbook for students on writing a flight controller ([in development](https://quadcopter.dev)).
+* *Position control and autonomous flights using external camera¹*.
+* [Building and running instructions](docs/build.md).
+
+*¹ — planned.*
+
+## It actually flies
+
+See detailed demo video (for version 0): https://youtu.be/8GzzIQ3C6DQ.
+
+<a href="https://youtu.be/8GzzIQ3C6DQ"><img width=500 src="https://i3.ytimg.com/vi/8GzzIQ3C6DQ/maxresdefault.jpg"></a>
+
+Version 1 test flight: https://t.me/opensourcequadcopter/42.
+
+<a href="https://t.me/opensourcequadcopter/42"><img width=500 src="docs/img/flight-video.jpg"></a>
+
+See the [user builds gallery](docs/user.md).
+
+<img src="docs/img/user/user.jpg" width=400>
+
+## Simulation
+
+The simulator is implemented using Gazebo and runs the original Arduino code:
+
+<img src="docs/img/simulator.png" width=500 alt="Flix simulator">
+
+See [instructions on running the simulation](docs/build.md).
+
+## Components (version 1)
+
+|Type|Part|Image|Quantity|
+|-|-|:-:|:-:|
+|Microcontroller board|ESP32 Mini|<img src="docs/img/esp32.jpg" width=100>|1|
+|IMU (and barometer²) board|GY‑91 (or other MPU‑9250/MPU‑6500 board), ICM‑20948³|<img src="docs/img/gy-91.jpg" width=90 align=center><img src="docs/img/icm-20948.jpg" width=100>|1|
+|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|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|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|4|
+|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 bottom 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)|<img src="docs/img/frame1.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:<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|
+|*RC transmitter (optional)*|*KINGKONG TINY X8 or other⁵*|<img src="docs/img/tx.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||||
+
+*² — barometer is not used for now.*<br>
+*³ — change `MPU9250` to `ICM20948` in `imu.ino` file if using ICM-20948 board.*<br>
+*⁴ — this frame is optimized for GY-91 board, if using other, the board mount holes positions should be modified.*<br>
+*⁵ — you may use any transmitter-receiver pair with SBUS interface.*
+
+Tools required for assembly:
+
+* 3D printer.
+* Soldering iron.
+* Solder wire (with flux).
+* Screwdrivers.
+* Multimeter.
+
+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 (version 1)
+
+### Simplified connection diagram
+
+<img src="docs/img/schematics1.svg" width=800 alt="Flix version 1 schematics">
+
+Motor connection scheme:
+
+<img src="docs/img/mosfet-connection.png" height=400 alt="MOSFET 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.
+* Connect the IMU board to the ESP32 Mini using VSPI, power it using 3.3V and GND pins:
+
+  |IMU pin|ESP32 pin|
+  |-|-|
+  |GND|GND|
+  |3.3V|3.3V|
+  |SCL *(SCK)*|SVP (GPIO18)|
+  |SDA *(MOSI)*|GPIO23|
+  |SAO *(MISO)*|GPIO19|
+  |NCS|GPIO5|
+
+* Solder pull-down resistors to the MOSFETs.
+* Connect the motors to the ESP32 Mini using MOSFETs, by following scheme:
+
+  |Motor|Position|Direction|Wires|GPIO|
+  |-|-|-|-|-|
+  |Motor 0|Rear left|Counter-clockwise|Black & White|GPIO12 (*TDI*)|
+  |Motor 1|Rear right|Clockwise|Blue & Red|GPIO13 (*TCK*)|
+  |Motor 2|Front right|Counter-clockwise|Black & White|GPIO14 (*TMS*)|
+  |Motor 3|Front left|Clockwise|Blue & Red|GPIO15 (*TD0*)|
+
+  Counter-clockwise motors have black and white wires and clockwise motors have blue and red wires.
+
+* Optionally connect the RC receiver to the ESP32's UART2:
+
+  |Receiver pin|ESP32 pin|
+  |-|-|
+  |GND|GND|
+  |VIN|VCC (or 3.3V depending on the receiver)|
+  |Signal (TX)|GPIO4⁶|
+
+*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.*
+
+### IMU placement
+
+Default IMU orientation in the code is **LFD** (Left-Forward-Down):
+
+<img src="docs/img/gy91-lfd.svg" width=400 alt="GY-91 axes">
+
+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.
+
+## Version 0
+
+See the information on the obsolete version 0 in the [corresponding article](docs/version0.md).
+
+## 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/.
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -0,0 +1,10 @@
+build:
+	mdbook build
+
+serve:
+	mdbook serve
+
+clean:
+	mdbook clean
+
+.PHONY: build serve clean
--- a/docs/alerts.py
+++ b/docs/alerts.py
@@ -0,0 +1,31 @@
+# https://rust-lang.github.io/mdBook/format/configuration/preprocessors.html
+# https://rust-lang.github.io/mdBook/for_developers/preprocessors.html
+
+import json
+import sys
+import re
+
+
+def transform_markdown_to_html(markdown_text):
+    def replace_blockquote(match):
+        tag = match.group(1).lower()
+        content = match.group(2).strip().replace('\n> ', ' ')
+        return f'<div class="alert alert-{tag}">{content}</div>\n'
+
+    pattern = re.compile(r'> \[!(NOTE|TIP|IMPORTANT|WARNING|CAUTION)\]\n>(.*?)\n?(?=(\n[^>]|\Z))', re.DOTALL)
+    transformed_text = pattern.sub(replace_blockquote, markdown_text)
+    return transformed_text
+
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1:
+        if sys.argv[1] == 'supports':
+            sys.exit(0)
+
+    context, book = json.load(sys.stdin)
+
+    for section in book['sections']:
+        if 'Chapter' in section:
+            section['Chapter']['content'] = transform_markdown_to_html(section['Chapter']['content'])
+
+    print(json.dumps(book))
--- a/docs/assembly.md
+++ b/docs/assembly.md
@@ -0,0 +1,29 @@
+# Brief assembly guide
+
+Soldered components ([schematics variant](https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612338222067&cot=14)):
+
+<img src="img/assembly/1.jpg" width=600>
+
+<br>Use double-sided tape to attach ESP32 to the top frame part (ESP32 holder):
+
+<img src="img/assembly/2.jpg" width=600>
+
+<br>Use two washers to screw the IMU board to the frame:
+
+<img src="img/assembly/3.jpg" width=600>
+
+<br>Screw the IMU with M3x5 screws as shown:
+
+<img src="img/assembly/4.jpg" width=600>
+
+<br>Install the motors, attach MOSFETs to the frame using tape:
+
+<img src="img/assembly/5.jpg" width=600>
+
+<br>Screw the ESP32 holder with M1.4x5 screws to the frame:
+
+<img src="img/assembly/6.jpg" width=600>
+
+<br>Assembled drone:
+
+<img src="img/assembly/7.jpg" width=600>
--- a/docs/assets/flix-frame-1.1.step
+++ b/docs/assets/flix-frame-1.1.step
--- a/docs/assets/flix-frame-1.1.stl
+++ b/docs/assets/flix-frame-1.1.stl
--- a/docs/book.css
+++ b/docs/book.css
@@ -0,0 +1,110 @@
+.sidebar-resize-handle { display: none !important; }
+
+footer {
+	contain: content;
+	border-top: 3px solid #f4f4f4;
+}
+
+footer a.telegram, footer a.github {
+	display: block;
+	margin-bottom: 10px;
+	margin-top: 10px;
+	display: flex;
+	align-items: center;
+	text-decoration: none;
+}
+
+.content .github, .content .telegram {
+	display: flex;
+	align-items: center;
+	text-align: center;
+	justify-content: center;
+}
+
+.telegram::before, .github::before {
+	font-family: FontAwesome;
+	margin-right: 0.3em;
+	font-size: 1.6em;
+	color: black;
+}
+
+.github::before {
+	content: "\f09b";
+}
+
+.telegram::before {
+	font-size: 1.4em;
+	color: #0084c5;
+	content: "\f2c6";
+}
+
+.content hr {
+	border: none;
+	border-top: 2px solid #c9c9c9;
+	margin: 2em 0;
+}
+
+.content img {
+	display: block;
+	margin: 0 auto;
+}
+
+.content img.border {
+	border: 1px solid #c9c9c9;
+}
+
+.firmware {
+	position: relative;
+	margin: 20px 0;
+	padding: 20px 20px;
+	padding-left: 60px;
+	color: var(--fg);
+	background-color: var(--quote-bg);
+	border-block-start: .1em solid var(--quote-border);
+	border-block-end: .1em solid var(--quote-border);
+}
+
+.firmware::before {
+	font-family: FontAwesome;
+	font-size: 1.5em;
+	content: "\f15b";
+	position: absolute;
+	width: 20px;
+	text-align: center;
+	left: 20px;
+}
+
+.alert {
+	margin-top: 20px;
+	margin-bottom: 20px;
+	position: relative;
+	border-left: 2px solid #0a69da;
+	padding: 20px;
+	padding-left: 60px;
+}
+
+.alert::before {
+	font-family: FontAwesome;
+	font-size: 1.5em;
+	color: #0a69da;
+	content: "\f05a";
+	position: absolute;
+	width: 20px;
+	text-align: center;
+	left: 20px;
+}
+
+.alert-tip { border-left-color: #1b7f37; }
+.alert-tip::before { color: #1b7f37; content: '\f0eb'; }
+
+.alert-caution { border-left-color: #cf212e; }
+.alert-caution::before { color: #cf212e; content: '\f071'; }
+
+.alert-important { border-left-color: #8250df; }
+.alert-important::before { color: #8250df; content: '\f06a'; }
+
+.alert-warning { border-left-color: #f0ad4e; }
+.alert-warning::before { color: #f0ad4e; content: '\f071'; }
+
+.alert-code { border-left-color: #333; }
+.alert-code::before { color: #333; content: '\f121'; }
--- a/docs/book.toml
+++ b/docs/book.toml
@@ -0,0 +1,22 @@
+[book]
+authors = ["Oleg Kalachev"]
+language = "ru"
+multilingual = false
+src = "book"
+title = "Полетный контроллер с нуля"
+description = "Учебник по разработке полетного контроллера квадрокоптера"
+
+[build]
+build-dir = "build"
+
+[output.html]
+additional-css = ["book.css", "zoom.css"]
+additional-js = ["zoom.js", "js.js"]
+edit-url-template = "https://github.com/okalachev/flix/blob/master/docs/{path}?plain=1"
+mathjax-support = true
+
+[output.html.code.hidelines]
+cpp = "//~"
+
+[preprocessor.alerts]
+command = "python3 alerts.py"
--- a/docs/book/README.md
+++ b/docs/book/README.md
@@ -0,0 +1,10 @@
+# Flix
+
+> [!IMPORTANT]
+> Flix — это проект по созданию открытого квадрокоптера на базе ESP32 с нуля и учебника по разработке полетных контроллеров.
+
+<img src="img/flix1.1.jpg" class="border" width=500 alt="Flix quadcopter">
+
+<p class="github">GitHub:&nbsp;<a href="https://github.com/okalachev/flix">github.com/okalachev/flix</a>.</p>
+
+<p class="telegram">Telegram-канал:&nbsp;<a href="https://t.me/opensourcequadcopter">@opensourcequadcopter</a>.</p>
--- a/docs/book/SUMMARY.md
+++ b/docs/book/SUMMARY.md
@@ -0,0 +1,22 @@
+<!-- markdownlint-disable MD041 -->
+<!-- markdownlint-disable MD042 -->
+
+[Главная](./README.md)
+
+* [Архитектура прошивки](firmware.md)
+
+# Учебник
+
+* [Основы]()
+* [Светодиод]()
+* [Моторы]()
+* [Радиоуправление]()
+* [Гироскоп](gyro.md)
+* [Акселерометр]()
+* [Оценка состояния]()
+* [PID-регулятор]()
+* [Режим ACRO]()
+* [Режим STAB]()
+* [Wi-Fi]()
+* [MAVLink]()
+* [Симуляция]()
--- a/docs/book/firmware.md
+++ b/docs/book/firmware.md
@@ -0,0 +1,32 @@
+# Архитектура прошивки
+
+<img src="img/dataflow.svg" width=800 alt="Firmware dataflow diagram">
+
+Главный цикл работает на частоте 1000 Гц. Передача данных между подсистемами происходит через глобальные переменные:
+
+* `t` *(float)* — текущее время шага, *с*.
+* `dt` *(float)* — дельта времени между текущим и предыдущим шагами, *с*.
+* `gyro` *(Vector)* — данные с гироскопа, *рад/с*.
+* `acc` *(Vector)* — данные с акселерометра, *м/с<sup>2</sup>*.
+* `rates` *(Vector)* — отфильтрованные угловые скорости, *рад/с*.
+* `attitude` *(Quaternion)* — оценка ориентации (положения) дрона.
+* `controls` *(float[])* — пользовательские управляющие сигналы с пульта, нормализованные в диапазоне [-1, 1].
+* `motors` *(float[])* — выходные сигналы на моторы, нормализованные в диапазоне [-1, 1] (возможно вращение в обратную сторону).
+
+## Исходные файлы
+
+Исходные файлы прошивки находятся в директории `flix`. Ключевые файлы:
+
+* [`flix.ino`](https://github.com/okalachev/flix/blob/canonical/flix/flix.ino) — основной входной файл, скетч Arduino. Включает определение глобальных переменных и главный цикл.
+* [`imu.ino`](https://github.com/okalachev/flix/blob/canonical/flix/imu.ino) — чтение данных с датчика IMU (гироскоп и акселерометр), калибровка IMU.
+* [`rc.ino`](https://github.com/okalachev/flix/blob/canonical/flix/rc.ino) — чтение данных с RC-приемника, калибровка RC.
+* [`mavlink.ino`](https://github.com/okalachev/flix/blob/canonical/flix/mavlink.ino) — взаимодействие с QGroundControl через MAVLink.
+* [`estimate.ino`](https://github.com/okalachev/flix/blob/canonical/flix/estimate.ino) — оценка ориентации дрона, комплементарный фильтр.
+* [`control.ino`](https://github.com/okalachev/flix/blob/canonical/flix/control.ino) — управление ориентацией и угловыми скоростями дрона, трехмерный двухуровневый каскадный PID-регулятор.
+* [`motors.ino`](https://github.com/okalachev/flix/blob/canonical/flix/motors.ino) — управление выходными сигналами на моторы через ШИМ.
+
+Вспомогательные файлы включают:
+
+* [`vector.h`](https://github.com/okalachev/flix/blob/canonical/flix/vector.h), [`quaternion.h`](https://github.com/okalachev/flix/blob/canonical/flix/quaternion.h) — реализация библиотек векторов и кватернионов проекта.
+* [`pid.h`](https://github.com/okalachev/flix/blob/canonical/flix/pid.h) — реализация общего ПИД-регулятора.
+* [`lpf.h`](https://github.com/okalachev/flix/blob/canonical/flix/lpf.h) — реализация общего фильтра нижних частот.
--- a/docs/book/gyro.md
+++ b/docs/book/gyro.md
@@ -0,0 +1,262 @@
+# Гироскоп
+
+<div class="firmware">
+	<strong>Файл прошивки Flix:</strong>
+	<a href="https://github.com/okalachev/flix/blob/canonical/flix/imu.ino"><code>imu.ino</code></a> <small>(каноничная версия)</small>.<br>
+	Текущая версия: <a href="https://github.com/okalachev/flix/blob/master/flix/imu.ino"><code>imu.ino</code></a>.
+</div>
+
+Поддержание стабильного полета квадрокоптера невозможно без датчиков обратной связи. Важнейший из них — это **MEMS-гироскоп**. MEMS-гироскоп это микроэлектромеханический аналог классического механического гироскопа.
+
+Механический гироскоп состоит из вращающегося диска, который сохраняет свою ориентацию в пространстве. Благодаря этому эффекту возможно определить ориентацию объекта в пространстве.
+
+В MEMS-гироскопе нет вращающихся частей, и он помещается в крошечную микросхему. Он может измерять только текущую угловую скорость вращения объекта вокруг трех осей: X, Y и Z.
+
+|Механический гироскоп|MEMS-гироскоп|
+|-|-|
+|<img src="img/gyroscope.jpg" width="300" alt="Механический гироскоп">|<img src="img/mpu9250.jpg" width="100" alt="MEMS-гироскоп MPU-9250">|
+
+MEMS-гироскоп обычно интегрирован в инерциальный модуль (IMU), в котором также находятся акселерометр и магнитометр. Модуль IMU часто называют 9-осевым датчиком, потому что он измеряет:
+
+* Угловую скорость вращения по трем осям (гироскоп).
+* Ускорение по трем осям (акселерометр).
+* Магнитное поле по трем осям (магнитометр).
+
+Flix поддерживает следующие модели IMU:
+
+* InvenSense MPU-9250.
+* InvenSense MPU-6500.
+* InvenSense ICM-20948.
+
+> [!NOTE]
+> MEMS-гироскоп измеряет угловую скорость вращения объекта.
+
+## Интерфейс подключения
+
+Большинство модулей IMU подключаются к микроконтроллеру через интерфейсы I²C и SPI. Оба этих интерфейса являются *шинами данных*, то есть позволяют подключить к одному микроконтроллеру несколько устройств.
+
+**Интерфейс I²C** использует два провода для передачи данных и тактового сигнала. Выбор устройства для коммуникации происходит при помощи передачи адреса устройства на шину. Разные устройства имеют разные адреса, и микроконтроллер может последовательно общаться с несколькими устройствами.
+
+**Интерфейс SPI** использует два провода для передачи данных, еще один для тактового сигнала и еще один для выбора устройства. При этом для каждого устройства на шине выделяется отдельный GPIO-пин для выбора. В разных реализациях этот пин называется CS/NCS (Chip Select) или SS (Slave Select). Когда CS-пин устройства активен (напряжение на нем низкое), устройство выбрано для общения.
+
+В полетных контроллерах IMU обычно подключают через SPI, потому что он обеспечивает значительно бо́льшую скорость передачи данных и меньшую задержку. Подключение IMU через интерфейс I²C (например, в случае нехватки пинов микроконтроллера) возможно, но не рекомендуется.
+
+Подключение IMU к микроконтроллеру ESP32 через интерфейс SPI выглядит так:
+
+|Пин платы IMU|Пин ESP32|
+|-|-|
+|VCC/3V3|3V3|
+|GND|GND|
+|SCL|IO18|
+|SDA *(MOSI)*|IO23|
+|SAO/AD0 *(MISO)*|IO19|
+|NCS|IO5|
+
+Кроме того, многие IMU могут «будить» микроконтроллер при наличии новых данных. Для этого используется пин INT, который подключается к любому GPIO-пину микроконтроллера. При такой конфигурации можно использовать прерывания для обработки новых данных с IMU, вместо периодического опроса датчика. Это позволяет снизить нагрузку на микроконтроллер в сложных алгоритмах управления.
+
+> [!WARNING]
+> На некоторых платах IMU, например, на ICM-20948, отсутствует стабилизатор напряжения, поэтому их нельзя подключать к пину VIN ESP32, который подает напряжение 5 В. Допустимо питание только от пина 3V3.
+
+## Работа с гироскопом
+
+Для взаимодействия с IMU, включая работу с гироскопом, в Flix используется библиотека *FlixPeriph*. Библиотека устанавливается через менеджер библиотек Arduino IDE:
+
+<img src="img/flixperiph.png" width="300">
+
+Чтобы работать с IMU, используется класс, соответствующий модели IMU: `MPU9250`, `MPU6500` или `ICM20948`. Классы для работы с разными IMU имеют единообразный интерфейс для основных операций, поэтому возможно легко переключаться между разными моделями IMU. Датчик MPU-6500 практически полностью совместим с MPU-9250, поэтому фактически класс `MPU9250` поддерживает обе модели.
+
+## Ориентация осей гироскопа
+
+Данные с гироскопа представляют собой угловую скорость вокруг трех осей: X, Y и Z. Ориентацию этих осей у IMU InvenSense можно легко определить по небольшой точке в углу чипа. Оси координат и направление вращения для измерений гироскопа обозначены на диаграмме:
+
+<img src="img/imu-axes.svg" width="300" alt="Оси координат IMU">
+
+Расположение осей координат в популярных платах IMU:
+
+|GY-91|MPU-92/65|ICM-20948|
+|-|-|-|
+|<img src="https://github.com/okalachev/flixperiph/raw/refs/heads/master/img/gy91-axes.svg" width="200" alt="Оси координат платы GY-91">|<img src="https://github.com/okalachev/flixperiph/raw/refs/heads/master/img/mpu9265-axes.svg" width="200" alt="Оси координат платы MPU-9265">|<img src="https://github.com/okalachev/flixperiph/raw/refs/heads/master/img/icm20948-axes.svg" width="200" alt="Оси координат платы ICM-20948">|
+
+Магнитометр IMU InvenSense обычно является отдельным устройством, интегрированным в чип, поэтому его оси координат могут отличаться. Библиотека FlixPeriph скрывает это различие и приводит данные с магнитометра к системе координат гироскопа и акселерометра.
+
+## Чтение данных
+
+Интерфейс библиотеки FlixPeriph соответствует стилю, принятому в Arduino. Для начала работы с IMU необходимо создать объект соответствующего класса и вызвать метод `begin()`. В конструктор класса передается интерфейс, по которому подключен IMU (SPI или I²C):
+
+```cpp
+#include <FlixPeriph.h>
+#include <SPI.h>
+
+MPU9250 IMU(SPI);
+
+void setup() {
+	Serial.begin(115200);
+	bool success = IMU.begin();
+	if (!success) {
+		Serial.println("Failed to initialize IMU");
+	}
+}
+```
+
+Для однократного считывания данных используется метод `read()`. Затем данные с гироскопа получаются при помощи метода `getGyro(x, y, z)`. Этот метод записывает в переменные `x`, `y` и `z` угловые скорости вокруг соответствующих осей в радианах в секунду.
+
+Если нужно гарантировать, что будут считаны новые данные, можно использовать метод `waitForData()`. Этот метод блокирует выполнение программы до тех пор, пока в IMU не появятся новые данные. Метод `waitForData()` позволяет привязать частоту главного цикла `loop` к частоте обновления данных IMU. Это удобно для организации главного цикла управления квадрокоптером.
+
+Программа для чтения данных с гироскопа и вывода их в консоль для построения графиков в Serial Plotter выглядит так:
+
+```cpp
+#include <FlixPeriph.h>
+#include <SPI.h>
+
+MPU9250 IMU(SPI);
+
+void setup() {
+	Serial.begin(115200);
+	bool success = IMU.begin();
+	if (!success) {
+		Serial.println("Failed to initialize IMU");
+	}
+}
+
+void loop() {
+	IMU.waitForData();
+
+	float gx, gy, gz;
+	IMU.getGyro(gx, gy, gz);
+
+	Serial.printf("gx:%f gy:%f gz:%f\n", gx, gy, gz);
+	delay(50); // замедление вывода
+}
+```
+
+После запуска программы в Serial Plotter можно увидеть графики угловых скоростей. Например, при вращениях IMU вокруг вертикальной оси Z графики будут выглядеть так:
+
+<img src="img/gyro-plotter.png">
+
+## Конфигурация гироскопа
+
+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 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 сэмплов, тем выше точность управления полетом, но и больше нагрузка на микроконтроллер.
+
+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 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 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 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 динамичных маневров.
+
+В библиотеке FlixPeriph диапазон измерений гироскопа устанавливается методом `setGyroRange()`:
+
+```cpp
+IMU.setGyroRange(IMU.GYRO_RANGE_2000DPS);
+```
+
+### LPF-фильтр
+
+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);
+```
+
+## 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*):
+
+\\[ gyro_{xyz}=rates_{xyz}+bias_{xyz}+noise \\]
+
+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:
+
+```cpp
+#include <FlixPeriph.h>
+#include <SPI.h>
+
+MPU9250 IMU(SPI);
+
+float gyroBiasX, gyroBiasY, gyroBiasZ; // bias гироскопа
+
+void setup() {
+	Serial.begin(115200);
+	bool success = IMU.begin();
+	if (!success) {
+		Serial.println("Failed to initialize IMU");
+	}
+	calibrateGyro();
+}
+
+void loop() {
+	float gx, gy, gz;
+	IMU.waitForData();
+	IMU.getGyro(gx, gy, gz);
+
+	// Устранение bias гироскопа
+	gx -= gyroBiasX;
+	gy -= gyroBiasY;
+	gz -= gyroBiasZ;
+
+	Serial.printf("gx:%f gy:%f gz:%f\n", gx, gy, gz);
+	delay(50); // замедление вывода
+}
+
+void calibrateGyro() {
+	const int samples = 1000;
+	Serial.println("Calibrating gyro, stand still");
+
+	gyroBiasX = 0;
+	gyroBiasY = 0;
+	gyroBiasZ = 0;
+
+	// Получение 1000 измерений гироскопа
+	for (int i = 0; i < samples; i++) {
+		IMU.waitForData();
+		float gx, gy, gz;
+		IMU.getGyro(gx, gy, gz);
+		gyroBiasX += gx;
+		gyroBiasY += gy;
+		gyroBiasZ += gz;
+	}
+
+	// Усреднение значений
+	gyroBiasX = gyroBiasX / samples;
+	gyroBiasY = gyroBiasY / samples;
+	gyroBiasZ = gyroBiasZ / samples;
+
+	Serial.printf("Gyro bias X: %f\n", gyroBiasX);
+	Serial.printf("Gyro bias Y: %f\n", gyroBiasY);
+	Serial.printf("Gyro bias Z: %f\n", gyroBiasZ);
+}
+```
+
+График данных с гироскопа в состоянии покоя без калибровки. Можно увидеть статическую ошибку каждой из осей:
+
+<img src="img/gyro-uncalibrated-plotter.png">
+
+График данных с гироскопа в состоянии покоя после калибровки:
+
+<img src="img/gyro-calibrated-plotter.png">
+
+Откалиброванные данные с гироскопа вместе с данными с акселерометра поступают в *подсистему оценки состояния*.
+
+## Дополнительные материалы
+
+* [MPU-9250 datasheet](https://invensense.tdk.com/wp-content/uploads/2015/02/PS-MPU-9250A-01-v1.1.pdf).
+* [MPU-6500 datasheet](https://invensense.tdk.com/wp-content/uploads/2020/06/PS-MPU-6500A-01-v1.3.pdf).
+* [ICM-20948 datasheet](https://invensense.tdk.com/wp-content/uploads/2016/06/DS-000189-ICM-20948-v1.3.pdf).
--- a/docs/book/img
+++ b/docs/book/img
@@ -0,0 +1 @@
+../img
--- a/docs/build.md
+++ b/docs/build.md
@@ -9,9 +9,9 @@ cd flix

 ## Simulation

-### Ubuntu
+### Ubuntu 20.04

-The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you have a newer version, consider using a virtual machine.
+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:

@@ -84,7 +84,7 @@ The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you h

 #### 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.
+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.
@@ -96,10 +96,9 @@ The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you h

 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 and stop the simulation.
-4. Copy the calibration results to the source code (`gazebo/joystick.h`).
-5. Run the simulation again.
-6. Use the USB remote control to fly the drone!
+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

@@ -107,10 +106,10 @@ The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you h

 1. Install [Arduino IDE](https://www.arduino.cc/en/software) (version 2 is recommended).
 2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
-3. Install ESP32 core, version 3.2.0. See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
+3. Install ESP32 core, version 3.1.0 (version 2.x is not supported). See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
 4. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
   * `FlixPeriph`, the latest version.
-   * `MAVLink`, version 2.0.16.
+   * `MAVLink`, version 2.0.12.
 5. Clone the project using git or [download the source code as a ZIP archive](https://codeload.github.com/okalachev/flix/zip/refs/heads/master).
 6. Open the downloaded Arduino sketch `flix/flix.ino` in Arduino IDE.
 7. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
@@ -119,6 +118,13 @@ The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you h
 ### Command line (Windows, Linux, macOS)

 1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
+
+   On Linux, use:
+
+   ```bash
+   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
+   ```
+
 2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
 3. Compile the firmware using `make`. Arduino dependencies will be installed automatically:

@@ -140,13 +146,15 @@ The latest version of Ubuntu supported by Gazebo 11 simulator is 22.04. If you h

 See other available Make commands in the [Makefile](../Makefile).

+> [!TIP]
+> You can test the firmware on a bare ESP32 board without connecting IMU and other peripherals. The Wi-Fi network `flix` should appear and all the basic functionality including CLI and QGroundControl connection should work.
+
 ### Setup and flight

 Before flight you need to calibrate the accelerometer:

-1. Open Serial Monitor in Arduino IDE (use use `make monitor` command in the command line).
-2. Type `ca` command there.
-3. Copy calibration results to the source code (`flix/imu.ino`).
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
+2. Type `ca` command there and follow the instructions.

 #### Control with smartphone

@@ -161,11 +169,33 @@ Before flight you need to calibrate the accelerometer:

 Before flight using remote control, you need to calibrate it:

-1. Open Serial Monitor in Arduino IDE (use use `make monitor` command in the command line).
-2. Type `cr` command there.
-3. Copy calibration results to the source code (`flix/rc.ino`).
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
+2. Type `cr` command there and follow the instructions.
+3. Use the remote control to fly the drone!

-Then you can use your remote control to fly the drone!
+#### Control with USB remote control
+
+If your drone doesn't have RC receiver installed, you can use USB remote control and QGroundControl app to fly it.
+
+1. Install [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html) app on your computer.
+2. Connect your USB remote control to the computer.
+3. Power up the drone.
+4. Connect your computer to the appeared `flix` Wi-Fi network.
+5. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
+6. Go the the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate you USB remote control there.
+7. Use the USB remote control to fly the drone!
+
+#### Adjusting parameters
+
+You can adjust some of the drone's parameters (include PID coefficients) in QGroundControl app. In order to do that, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Parameters*.
+
+<img src="img/parameters.png" width="400">
+
+#### CLI access
+
+In addition to accessing the drone's command line interface (CLI) using the serial port, you can also access it with QGroundControl using Wi-Fi connection. To do that, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
+
+<img src="img/cli.png" width="400">

 > [!NOTE]
 > If something goes wrong, go to the [Troubleshooting](troubleshooting.md) article.
--- a/docs/firmware.md
+++ b/docs/firmware.md
@@ -6,14 +6,14 @@

 The main loop is running at 1000 Hz. All the dataflow is happening through global variables (for simplicity):

-* `t` *(float)* — current step time, *s*.
+* `t` *(double)* — current step time, *s*.
 * `dt` *(float)* — time delta between the current and previous steps, *s*.
 * `gyro` *(Vector)* — data from the gyroscope, *rad/s*.
 * `acc` *(Vector)* — acceleration data from the accelerometer, *m/s<sup>2</sup>*.
 * `rates` *(Vector)* — filtered angular rates, *rad/s*.
 * `attitude` *(Quaternion)* — estimated attitude (orientation) of drone.
-* `controlRoll`, `controlPitch`, ... *(float[])* — pilot's control inputs, range [-1, 1].
-* `motors` *(float[])* — motor outputs, normalized to [0, 1] range; reverse rotation is possible.
+* `controls` *(float[])* — user control inputs from the RC, normalized to [-1, 1] range.
+* `motors` *(float[])* — motor outputs, normalized to [-1, 1] range; reverse rotation is possible.

 ## Source files

--- a/docs/img/assembly/1.jpg
+++ b/docs/img/assembly/1.jpg
--- a/docs/img/assembly/2.jpg
+++ b/docs/img/assembly/2.jpg
--- a/docs/img/assembly/3.jpg
+++ b/docs/img/assembly/3.jpg
--- a/docs/img/assembly/4.jpg
+++ b/docs/img/assembly/4.jpg
--- a/docs/img/assembly/5.jpg
+++ b/docs/img/assembly/5.jpg
--- a/docs/img/assembly/6.jpg
+++ b/docs/img/assembly/6.jpg
--- a/docs/img/assembly/7.jpg
+++ b/docs/img/assembly/7.jpg
--- a/docs/img/cli.png
+++ b/docs/img/cli.png
--- a/docs/img/flix1.1.jpg
+++ b/docs/img/flix1.1.jpg
--- a/docs/img/flixperiph.png
+++ b/docs/img/flixperiph.png
--- a/docs/img/gyro-calibrated-plotter.png
+++ b/docs/img/gyro-calibrated-plotter.png
--- a/docs/img/gyro-plotter.png
+++ b/docs/img/gyro-plotter.png
--- a/docs/img/gyro-uncalibrated-plotter.png
+++ b/docs/img/gyro-uncalibrated-plotter.png
--- a/docs/img/gyroscope.jpg
+++ b/docs/img/gyroscope.jpg
--- a/docs/img/imu-axes.svg
+++ b/docs/img/imu-axes.svg
@@ -0,0 +1,119 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 544.13 637.15">
+  <defs>
+    <style>
+      .a {
+        fill: #dbe1e2;
+      }
+
+      .b {
+        fill: #c2c1c0;
+      }
+
+      .c {
+        fill: #c6c6c5;
+      }
+
+      .d {
+        fill: #ec7d23;
+      }
+
+      .e {
+        font-size: 50px;
+        font-family: Tahoma;
+      }
+
+      .e, .n {
+        fill: #010101;
+      }
+
+      .f {
+        opacity: 0.8;
+      }
+
+      .g, .i, .k, .m {
+        fill: none;
+        stroke-width: 10px;
+      }
+
+      .g {
+        stroke: #0577ba;
+      }
+
+      .g, .i, .k {
+        stroke-linejoin: bevel;
+      }
+
+      .h {
+        fill: #0577ba;
+      }
+
+      .i {
+        stroke: #76c043;
+      }
+
+      .j {
+        fill: #76c043;
+      }
+
+      .k {
+        stroke: #d71f26;
+      }
+
+      .l {
+        fill: #d71f26;
+      }
+
+      .m {
+        stroke: #010101;
+        stroke-miterlimit: 10;
+      }
+    </style>
+  </defs>
+  <g>
+    <g>
+      <rect class="a" x="51.25" y="538.09" width="111.96" height="44.06"/>
+      <polygon class="b" points="204.47 515.98 163.21 582.15 163.21 538.09 204.47 471.91 204.47 515.98"/>
+      <polygon class="c" points="163.21 538.19 51.25 538.19 92.46 471.91 204.42 471.91 163.21 538.19"/>
+      <ellipse class="d" cx="101.09" cy="480" rx="7.45" ry="3.7" transform="translate(-117.09 40.67) rotate(-14.52)"/>
+    </g>
+    <text class="e" transform="translate(166.62 107.43)">Z</text>
+    <g class="f">
+      <g>
+        <line class="g" x1="127.84" y1="505.05" x2="127.84" y2="70.04"/>
+        <polygon class="h" points="145.79 75.3 127.84 44.21 109.89 75.3 145.79 75.3"/>
+      </g>
+    </g>
+    <g class="f">
+      <g>
+        <line class="i" x1="127.84" y1="505.05" x2="315.74" y2="203.61"/>
+        <polygon class="j" points="328.2 217.57 329.41 181.69 297.73 198.57 328.2 217.57"/>
+      </g>
+    </g>
+    <text class="e" transform="translate(338.14 279.7)">Y</text>
+    <g class="f">
+      <g>
+        <line class="k" x1="127.94" y1="504.62" x2="467.04" y2="504.62"/>
+        <polygon class="l" points="461.79 522.58 492.87 504.62 461.79 486.67 461.79 522.58"/>
+      </g>
+    </g>
+    <text class="e" transform="translate(438.99 582.15)">X</text>
+    <g class="f">
+      <g>
+        <path class="m" d="M80,98.74a52.66,52.66,0,1,0,98.43,36.72"/>
+        <polygon class="n" points="190.29 140.9 180.45 116.91 164.59 137.41 190.29 140.9"/>
+      </g>
+    </g>
+    <g class="f">
+      <g>
+        <path class="m" d="M474,467.75a52.66,52.66,0,1,0-59.23,86.77"/>
+        <polygon class="n" points="406.68 564.7 432.32 560.9 416.21 540.59 406.68 564.7"/>
+      </g>
+    </g>
+    <g class="f">
+      <g>
+        <path class="m" d="M222.38,257.69a52.66,52.66,0,1,1,93.83,47.25"/>
+        <polygon class="n" points="308.22 293.44 303.95 319.01 328.23 309.93 308.22 293.44"/>
+      </g>
+    </g>
+  </g>
+</svg>
--- a/docs/img/mpu9250.jpg
+++ b/docs/img/mpu9250.jpg
--- a/docs/img/parameters.png
+++ b/docs/img/parameters.png
--- a/docs/img/user/alexey_karakash/1.jpg
+++ b/docs/img/user/alexey_karakash/1.jpg
--- a/docs/img/user/alexey_karakash/2.jpg
+++ b/docs/img/user/alexey_karakash/2.jpg
--- a/docs/img/user/alexey_karakash/3.jpg
+++ b/docs/img/user/alexey_karakash/3.jpg
--- a/docs/img/user/alexey_karakash/4.jpg
+++ b/docs/img/user/alexey_karakash/4.jpg
--- a/docs/img/user/alexey_karakash/5.jpg
+++ b/docs/img/user/alexey_karakash/5.jpg
--- a/docs/img/user/alexey_karakash/video.jpg
+++ b/docs/img/user/alexey_karakash/video.jpg
--- a/docs/img/user/fisheyeu/1.jpg
+++ b/docs/img/user/fisheyeu/1.jpg
--- a/docs/img/user/fisheyeu/2.jpg
+++ b/docs/img/user/fisheyeu/2.jpg
--- a/docs/img/user/jeka_chex/1.jpg
+++ b/docs/img/user/jeka_chex/1.jpg
--- a/docs/img/user/jeka_chex/2.jpg
+++ b/docs/img/user/jeka_chex/2.jpg
--- a/docs/img/user/jeka_chex/3.jpg
+++ b/docs/img/user/jeka_chex/3.jpg
--- a/docs/img/user/jeka_chex/4.jpg
+++ b/docs/img/user/jeka_chex/4.jpg
--- a/docs/img/user/jeka_chex/5.jpg
+++ b/docs/img/user/jeka_chex/5.jpg
--- a/docs/img/user/jeka_chex/video-fpv.jpg
+++ b/docs/img/user/jeka_chex/video-fpv.jpg
--- a/docs/img/user/jeka_chex/video.jpg
+++ b/docs/img/user/jeka_chex/video.jpg
--- a/docs/img/user/p_kabakov/1.jpg
+++ b/docs/img/user/p_kabakov/1.jpg
--- a/docs/img/user/p_kabakov/2.jpg
+++ b/docs/img/user/p_kabakov/2.jpg
--- a/docs/img/user/p_kabakov/3.jpg
+++ b/docs/img/user/p_kabakov/3.jpg
--- a/docs/img/user/p_kabakov/wifirc.jpg
+++ b/docs/img/user/p_kabakov/wifirc.jpg
--- a/docs/img/user/peter_ukhov-2/1.jpg
+++ b/docs/img/user/peter_ukhov-2/1.jpg
--- a/docs/img/user/peter_ukhov-2/2.jpg
+++ b/docs/img/user/peter_ukhov-2/2.jpg
--- a/docs/img/user/peter_ukhov-2/video.jpg
+++ b/docs/img/user/peter_ukhov-2/video.jpg
--- a/docs/img/user/peter_ukhov/1.jpg
+++ b/docs/img/user/peter_ukhov/1.jpg
--- a/docs/img/user/peter_ukhov/2.jpg
+++ b/docs/img/user/peter_ukhov/2.jpg
--- a/docs/img/user/peter_ukhov/3.jpg
+++ b/docs/img/user/peter_ukhov/3.jpg
--- a/docs/img/user/peter_ukhov/video.jpg
+++ b/docs/img/user/peter_ukhov/video.jpg
--- a/docs/img/user/rudpa/1.jpg
+++ b/docs/img/user/rudpa/1.jpg
--- a/docs/img/user/rudpa/2.jpg
+++ b/docs/img/user/rudpa/2.jpg
--- a/docs/img/user/rudpa/3.jpg
+++ b/docs/img/user/rudpa/3.jpg
--- a/docs/img/user/rudpa/video.jpg
+++ b/docs/img/user/rudpa/video.jpg
--- a/docs/img/user/user.jpg
+++ b/docs/img/user/user.jpg
--- a/docs/img/user/yi_lun/1.jpg
+++ b/docs/img/user/yi_lun/1.jpg
--- a/docs/img/user/yi_lun/2.jpg
+++ b/docs/img/user/yi_lun/2.jpg
--- a/docs/js.js
+++ b/docs/js.js
@@ -0,0 +1,7 @@
+// Enable zoom on images larger than 300px
+document.querySelectorAll('.content img').forEach(function (img) {
+	var width = img.getAttribute('width');
+	if (!width || width >= 300) {
+		img.setAttribute('data-action', 'zoom');
+	}
+});
--- a/docs/theme/index.hbs
+++ b/docs/theme/index.hbs
@@ -0,0 +1,336 @@
+<!DOCTYPE HTML>
+<html lang="{{ language }}" class="{{ default_theme }} sidebar-visible" dir="{{ text_direction }}">
+    <head>
+        <!-- Book generated using mdBook -->
+        <meta charset="UTF-8">
+        <title>{{ title }}</title>
+        {{#if is_print }}
+        <meta name="robots" content="noindex">
+        {{/if}}
+        {{#if base_url}}
+        <base href="{{ base_url }}">
+        {{/if}}
+
+
+        <!-- Custom HTML head -->
+        {{> head}}
+
+        <meta name="description" content="{{ description }}">
+        <meta name="viewport" content="width=device-width, initial-scale=1">
+        <meta name="theme-color" content="#ffffff">
+
+        {{#if favicon_svg}}
+        <link rel="icon" href="{{ path_to_root }}favicon.svg">
+        {{/if}}
+        {{#if favicon_png}}
+        <link rel="shortcut icon" href="{{ path_to_root }}favicon.png">
+        {{/if}}
+        <link rel="stylesheet" href="{{ path_to_root }}css/variables.css">
+        <link rel="stylesheet" href="{{ path_to_root }}css/general.css">
+        <link rel="stylesheet" href="{{ path_to_root }}css/chrome.css">
+        {{#if print_enable}}
+        <link rel="stylesheet" href="{{ path_to_root }}css/print.css" media="print">
+        {{/if}}
+
+        <!-- Fonts -->
+        <link rel="stylesheet" href="{{ path_to_root }}FontAwesome/css/font-awesome.css">
+        {{#if copy_fonts}}
+        <link rel="stylesheet" href="{{ path_to_root }}fonts/fonts.css">
+        {{/if}}
+
+        <!-- Highlight.js Stylesheets -->
+        <link rel="stylesheet" href="{{ path_to_root }}highlight.css">
+        <link rel="stylesheet" href="{{ path_to_root }}tomorrow-night.css">
+        <link rel="stylesheet" href="{{ path_to_root }}ayu-highlight.css">
+
+        <!-- Custom theme stylesheets -->
+        {{#each additional_css}}
+        <link rel="stylesheet" href="{{ ../path_to_root }}{{ this }}">
+        {{/each}}
+
+        {{#if mathjax_support}}
+        <!-- MathJax -->
+        <script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
+        {{/if}}
+
+        <!-- Provide site root to javascript -->
+        <script>
+            var path_to_root = "{{ path_to_root }}";
+            var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "{{ preferred_dark_theme }}" : "{{ default_theme }}";
+        </script>
+        <!-- Start loading toc.js asap -->
+        <script src="{{ path_to_root }}toc.js"></script>
+
+        <!-- Yandex.Metrika counter -->
+        <script type="text/javascript" > (function(m,e,t,r,i,k,a){m[i]=m[i]||function(){(m[i].a=m[i].a||[]).push(arguments)}; m[i].l=1*new Date(); for (var j = 0; j < document.scripts.length; j++) {if (document.scripts[j].src === r) { return; }} k=e.createElement(t),a=e.getElementsByTagName(t)[0],k.async=1,k.src=r,a.parentNode.insertBefore(k,a)}) (window, document, "script", "https://mc.yandex.ru/metrika/tag.js", "ym"); ym(97589916, "init", { clickmap:true, trackLinks:true, accurateTrackBounce:true }); </script> <noscript><div><img src="https://mc.yandex.ru/watch/97589916" style="position:absolute; left:-9999px;" alt="" /></div></noscript> <!-- /Yandex.Metrika counter -->
+    </head>
+    <body>
+    <div id="body-container">
+        <!-- Work around some values being stored in localStorage wrapped in quotes -->
+        <script>
+            try {
+                var theme = localStorage.getItem('mdbook-theme');
+                var sidebar = localStorage.getItem('mdbook-sidebar');
+
+                if (theme.startsWith('"') && theme.endsWith('"')) {
+                    localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
+                }
+
+                if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
+                    localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
+                }
+            } catch (e) { }
+        </script>
+
+        <!-- Set the theme before any content is loaded, prevents flash -->
+        <script>
+            var theme;
+            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
+            if (theme === null || theme === undefined) { theme = default_theme; }
+            const html = document.documentElement;
+            html.classList.remove('{{ default_theme }}')
+            html.classList.add(theme);
+            html.classList.add("js");
+        </script>
+
+        <input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
+
+        <!-- Hide / unhide sidebar before it is displayed -->
+        <script>
+            var sidebar = null;
+            var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
+            if (document.body.clientWidth >= 1080) {
+                try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
+                sidebar = sidebar || 'visible';
+            } else {
+                sidebar = 'hidden';
+            }
+            sidebar_toggle.checked = sidebar === 'visible';
+            html.classList.remove('sidebar-visible');
+            html.classList.add("sidebar-" + sidebar);
+        </script>
+
+        <nav id="sidebar" class="sidebar" aria-label="Table of contents">
+            <!-- populated by js -->
+            <mdbook-sidebar-scrollbox class="sidebar-scrollbox">
+                <footer>
+                    <a href="https://github.com/okalachev/flix" class="github">GitHub</a>
+                    <a href="https://t.me/opensourcequadcopter" class="telegram">Telegram-канал</a>
+                    💰 Поддержать проект:
+                    <iframe style="margin-top: 0.4em;" src="https://yoomoney.ru/quickpay/fundraise/button?billNumber=16U9OH2S4IT.241205&" width="330" height="50" frameborder="0" allowtransparency="true" scrolling="no"></iframe>
+                    &copy; 2024 Олег Калачев
+                </footer>
+            </mdbook-sidebar-scrollbox>
+            <noscript>
+                <iframe class="sidebar-iframe-outer" src="{{ path_to_root }}toc.html"></iframe>
+            </noscript>
+            <div id="sidebar-resize-handle" class="sidebar-resize-handle">
+                <div class="sidebar-resize-indicator"></div>
+            </div>
+        </nav>
+
+        <div id="page-wrapper" class="page-wrapper">
+
+            <div class="page">
+                {{> header}}
+                <div id="menu-bar-hover-placeholder"></div>
+                <div id="menu-bar" class="menu-bar sticky">
+                    <div class="left-buttons">
+                        <label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
+                            <i class="fa fa-bars"></i>
+                        </label>
+                        <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
+                            <i class="fa fa-paint-brush"></i>
+                        </button>
+                        <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
+                            <li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
+                            <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
+                        </ul>
+                        {{#if search_enabled}}
+                        <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
+                            <i class="fa fa-search"></i>
+                        </button>
+                        {{/if}}
+                    </div>
+
+                    <h1 class="menu-title">{{ book_title }}</h1>
+
+                    <div class="right-buttons">
+                        {{#if print_enable}}
+                        <a href="{{ path_to_root }}print.html" title="Print this book" aria-label="Print this book">
+                            <i id="print-button" class="fa fa-print"></i>
+                        </a>
+                        {{/if}}
+                        {{#if git_repository_url}}
+                        <a href="{{git_repository_url}}" title="Git repository" aria-label="Git repository">
+                            <i id="git-repository-button" class="fa {{git_repository_icon}}"></i>
+                        </a>
+                        {{/if}}
+                        {{#if git_repository_edit_url}}
+                        <a href="{{git_repository_edit_url}}" title="Suggest an edit" aria-label="Suggest an edit">
+                            <i id="git-edit-button" class="fa fa-edit"></i>
+                        </a>
+                        {{/if}}
+
+                    </div>
+                </div>
+
+                {{#if search_enabled}}
+                <div id="search-wrapper" class="hidden">
+                    <form id="searchbar-outer" class="searchbar-outer">
+                        <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
+                    </form>
+                    <div id="searchresults-outer" class="searchresults-outer hidden">
+                        <div id="searchresults-header" class="searchresults-header"></div>
+                        <ul id="searchresults">
+                        </ul>
+                    </div>
+                </div>
+                {{/if}}
+
+                <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
+                <script>
+                    document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
+                    document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
+                    Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
+                        link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
+                    });
+                </script>
+
+                <div id="content" class="content">
+                    <main>
+                        {{{ content }}}
+                    </main>
+
+                    <nav class="nav-wrapper" aria-label="Page navigation">
+                        <!-- Mobile navigation buttons -->
+                        {{#previous}}
+                            <a rel="prev" href="{{ path_to_root }}{{link}}" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
+                                <i class="fa fa-angle-left"></i>
+                            </a>
+                        {{/previous}}
+
+                        {{#next}}
+                            <a rel="next prefetch" href="{{ path_to_root }}{{link}}" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                                <i class="fa fa-angle-right"></i>
+                            </a>
+                        {{/next}}
+
+                        <div style="clear: both"></div>
+                    </nav>
+                </div>
+            </div>
+
+            <nav class="nav-wide-wrapper" aria-label="Page navigation">
+                {{#previous}}
+                    <a rel="prev" href="{{ path_to_root }}{{link}}" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
+                        <i class="fa fa-angle-left"></i>
+                    </a>
+                {{/previous}}
+
+                {{#next}}
+                    <a rel="next prefetch" href="{{ path_to_root }}{{link}}" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                        <i class="fa fa-angle-right"></i>
+                    </a>
+                {{/next}}
+            </nav>
+
+        </div>
+
+        {{#if live_reload_endpoint}}
+        <!-- Livereload script (if served using the cli tool) -->
+        <script>
+            const wsProtocol = location.protocol === 'https:' ? 'wss:' : 'ws:';
+            const wsAddress = wsProtocol + "//" + location.host + "/" + "{{{live_reload_endpoint}}}";
+            const socket = new WebSocket(wsAddress);
+            socket.onmessage = function (event) {
+                if (event.data === "reload") {
+                    socket.close();
+                    location.reload();
+                }
+            };
+
+            window.onbeforeunload = function() {
+                socket.close();
+            }
+        </script>
+        {{/if}}
+
+        {{#if google_analytics}}
+        <!-- Google Analytics Tag -->
+        <script>
+            var localAddrs = ["localhost", "127.0.0.1", ""];
+
+            // make sure we don't activate google analytics if the developer is
+            // inspecting the book locally...
+            if (localAddrs.indexOf(document.location.hostname) === -1) {
+                (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+                (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
+                m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+                })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
+
+                ga('create', '{{google_analytics}}', 'auto');
+                ga('send', 'pageview');
+            }
+        </script>
+        {{/if}}
+
+        {{#if playground_line_numbers}}
+        <script>
+            window.playground_line_numbers = true;
+        </script>
+        {{/if}}
+
+        {{#if playground_copyable}}
+        <script>
+            window.playground_copyable = true;
+        </script>
+        {{/if}}
+
+        {{#if playground_js}}
+        <script src="{{ path_to_root }}ace.js"></script>
+        <script src="{{ path_to_root }}editor.js"></script>
+        <script src="{{ path_to_root }}mode-rust.js"></script>
+        <script src="{{ path_to_root }}theme-dawn.js"></script>
+        <script src="{{ path_to_root }}theme-tomorrow_night.js"></script>
+        {{/if}}
+
+        {{#if search_js}}
+        <script src="{{ path_to_root }}elasticlunr.min.js"></script>
+        <script src="{{ path_to_root }}mark.min.js"></script>
+        <script src="{{ path_to_root }}searcher.js"></script>
+        {{/if}}
+
+        <script src="{{ path_to_root }}clipboard.min.js"></script>
+        <script src="{{ path_to_root }}highlight.js"></script>
+        <script src="{{ path_to_root }}book.js"></script>
+
+        <!-- Custom JS scripts -->
+        {{#each additional_js}}
+        <script src="{{ ../path_to_root }}{{this}}"></script>
+        {{/each}}
+
+        {{#if is_print}}
+        {{#if mathjax_support}}
+        <script>
+        window.addEventListener('load', function() {
+            MathJax.Hub.Register.StartupHook('End', function() {
+                window.setTimeout(window.print, 100);
+            });
+        });
+        </script>
+        {{else}}
+        <script>
+        window.addEventListener('load', function() {
+            window.setTimeout(window.print, 100);
+        });
+        </script>
+        {{/if}}
+        {{/if}}
+
+    </div>
+    </body>
+</html>
--- a/docs/troubleshooting.md
+++ b/docs/troubleshooting.md
@@ -0,0 +1,36 @@
+# Troubleshooting
+
+## The sketch doesn't compile
+
+Do the following:
+
+* **Check ESP32 core is installed**. Check if the version matches the one used in the [tutorial](build.md#firmware).
+* **Check libraries**. Install all the required libraries from the tutorial. Make sure there are no MPU9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
+
+## The drone doesn't fly
+
+Do the following:
+
+* **Check the battery voltage**. Use a multimeter to measure the battery voltage. It should be in range of 3.7-4.2 V.
+* **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.
+* **Make sure correct IMU model is chosen**. If using ICM-20948 board, change `MPU9250` to `ICM20948` everywhere in the `imu.ino` file.
+* **Check if the CLI is working**. Perform `help` command in Serial Monitor. You should see the list of available commands. You can also access the CLI using QGroundControl (*Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*).
+* **Configure QGroundControl correctly before connecting to the drone** if you use it to control the drone. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
+* **Make sure you're not moving the drone several seconds after the power on**. The drone calibrates its gyroscope on the start so it should stay still for a while.
+* **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.
+* **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 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.
+* **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).
+* **Calibrate the RC** if you use it. Type `cr` command in Serial Monitor and follow the instructions.
+* **Check the RC data** if you use it. Use `rc` command, `Control` should show correct values between -1 and 1, and between 0 and 1 for the throttle.
+* **Check the IMU output using QGroundControl**. Connect to the drone using QGroundControl on your computer. Go to the *Analyze* tab, *MAVLINK Inspector*. Plot the data from the `SCALED_IMU` message. The gyroscope and accelerometer data should change according to the drone movement.
+* **Check the gyroscope only attitude estimation**. Comment out `applyAcc();` line in `estimate.ino` and check if the attitude estimation in QGroundControl. It should be stable, but only drift very slowly.
--- a/docs/user.md
+++ b/docs/user.md
@@ -0,0 +1,135 @@
+# Hall of fame
+
+This page contains user-built drones based on the Flix project. Publish your projects into the official Telegram-chat: [@opensourcequadcopterchat](https://t.me/opensourcequadcopterchat) or send materials as a pull request.
+
+---
+
+Author: [@jeka_chex](https://t.me/jeka_chex).<br>
+Features: custom frame, FPV camera, 3-blade 31 mm propellers.<br>
+Motor drivers: AON7410 MOSFET + capacitors.<br>
+Custom frame files: https://drive.google.com/drive/folders/1QCIc-_YYFxJN4cMhVLjL5SflqegvCowm?usp=share_link.<br>
+
+**Flight video:**
+
+<a href="https://drive.google.com/file/d/1VnWI5YVPojfqsfpyLX4v2V9zHi9adwcd/view?usp=sharing"><img height=300 src="img/user/jeka_chex/video.jpg"></a>
+
+**FPV flight video:**
+
+<a href="https://drive.google.com/file/d/1RSU6VWs9omsge4hGloH5NQqnxvLyhMKB/view?usp=sharing"><img height=300 src="img/user/jeka_chex/video-fpv.jpg"></a>
+
+<table>
+	<tr>
+		<td><img src="img/user/jeka_chex/1.jpg" height=150></td>
+		<td><img src="img/user/jeka_chex/2.jpg" height=150></td>
+		<td><img src="img/user/jeka_chex/3.jpg" height=150></td>
+		<td><img src="img/user/jeka_chex/4.jpg" height=150></td>
+		<td><img src="img/user/jeka_chex/5.jpg" height=150></td>
+	</tr>
+</table>
+
+---
+
+Author: [@fisheyeu](https://t.me/fisheyeu).<br>
+[Video](https://drive.google.com/file/d/1IT4eMmWPZpmaZR_qsIRmNJ52hYkFB_0q/view?usp=share_link).
+
+<table>
+	<tr>
+		<td><img src="img/user/fisheyeu/1.jpg" height=300></td>
+		<td><img src="img/user/fisheyeu/2.jpg" height=300></td>
+	</tr>
+</table>
+
+---
+
+Author: [@p_kabakov](https://t.me/p_kabakov).<br>
+Custom propellers guard 3D-model: https://drive.google.com/file/d/1TKnzwvrZYzYuRTLLERNmnKH71H9n4Xj_/view?usp=share_link.<br>
+Features: ESP32-C3 microcontroller is used.<br>
+[Video](https://drive.google.com/file/d/1B0NMcsk0fgwUgNr9XuLOdR2yYCuaj008/view?usp=share_link).
+
+<table>
+	<tr>
+		<td><img src="img/user/p_kabakov/1.jpg" width=150></td>
+		<td><img src="img/user/p_kabakov/2.jpg" width=150></td>
+		<td><img src="img/user/p_kabakov/3.jpg" width=150></td>
+	</tr>
+</table>
+
+**Custom Wi-Fi RC control:**
+
+<a href="https://github.com/pavelkabakov/flix/blob/master/rc_control_v1/IMG_20250221_195756.jpg"><img height=300 src="img/user/p_kabakov/wifirc.jpg"></a>
+
+See source and description (in Russian): https://github.com/pavelkabakov/flix/tree/master/rc_control_v1.
+
+---
+
+Author: [@yi_lun](https://t.me/yi_lun).<br>
+[Video](https://drive.google.com/file/d/1TkSuvHQ_0qQPFUpY5XjJzmhnpX_07cTg/view?usp=share_link).
+
+<table>
+	<tr>
+		<td><img src="img/user/yi_lun/1.jpg" width=300></td>
+		<td><img src="img/user/yi_lun/2.jpg" width=300></td>
+	</tr>
+</table>
+
+---
+
+Author: [@peter_ukhov](https://t.me/peter_ukhov).<br>
+Features: customized ESP32 holder, GY-ICM20948V2 IMU board, boost-converter for powering the ESP32.<br>
+Files for 3D-printing: https://drive.google.com/file/d/1Sma-FEzFBj2HA5ixJtUyH0uWixvr6vdK/view?usp=share_link.<br>
+Schematics: https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612179508274&cot=14.<br>
+
+<a href="https://www.youtube.com/watch?v=wi4w_hOmKcQ"><img width=500 src="img/user/peter_ukhov-2/video.jpg"></a>
+
+<table>
+	<tr>
+		<td><img src="img/user/peter_ukhov-2/1.jpg" width=300></td>
+		<td><img src="img/user/peter_ukhov-2/2.jpg" width=300></td>
+	</tr>
+</table>
+
+---
+
+Author: [@Alexey_Karakash](https://t.me/Alexey_Karakash).<br>
+Files for 3D printing of the custom frame: https://drive.google.com/file/d/1tkNmujrHrKpTMVtsRH3mor2zdAM0JHum/view?usp=share_link.<br>
+
+<a href="https://t.me/opensourcequadcopter/61"><img width=500 src="img/user/alexey_karakash/video.jpg"></a>
+
+<table>
+	<tr>
+		<td><img src="img/user/alexey_karakash/1.jpg" height=150></td>
+		<td><img src="img/user/alexey_karakash/2.jpg" height=150></td>
+		<td><img src="img/user/alexey_karakash/3.jpg" height=150></td>
+		<td><img src="img/user/alexey_karakash/4.jpg" height=150></td>
+		<td><img src="img/user/alexey_karakash/5.jpg" height=150></td>
+	</tr>
+</table>
+
+---
+
+Author: [@rudpa](https://t.me/rudpa).<br>
+
+<a href="https://t.me/opensourcequadcopter/46"><img width=500 src="img/user/rudpa/video.jpg"></a>
+
+<table>
+	<tr>
+		<td><img src="img/user/rudpa/1.jpg" height=150></td>
+		<td><img src="img/user/rudpa/2.jpg" height=150></td>
+		<td><img src="img/user/rudpa/3.jpg" height=150></td>
+	</tr>
+</table>
+
+---
+
+Author: [@peter_ukhov](https://t.me/peter_ukhov).<br>
+Schematics: https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612338222067&cot=14.<br>
+
+<a href="https://t.me/opensourcequadcopter/24"><img width=500 src="img/user/peter_ukhov/video.jpg"></a>
+
+<table>
+	<tr>
+		<td><img src="img/user/peter_ukhov/1.jpg" height=150></td>
+		<td><img src="img/user/peter_ukhov/2.jpg" height=150></td>
+		<td><img src="img/user/peter_ukhov/3.jpg" height=150></td>
+	</tr>
+</table>
--- a/docs/version0.md
+++ b/docs/version0.md
@@ -0,0 +1,30 @@
+# Flix version 0
+
+Flix version 0 (obsolete):
+
+<img src="img/flix.jpg" width=500 alt="Flix quadcopter">
+
+## Components list
+
+|Type|Part|Image|Quantity|
+|-|-|-|-|
+|Microcontroller board|ESP32 Mini|<img src="img/esp32.jpg" width=100>|1|
+|IMU and barometer² board|GY-91 (or other MPU-9250 board)|<img src="img/gy-91.jpg" width=100>|1|
+|Quadcopter frame|K100|<img src="img/frame.jpg" width=100>|1|
+|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/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|||
+|Battery charger||<img src="img/charger.jpg" width=100>|1|
+|Wires, connectors, tape, ...||||
+
+*\* — not needed as ESP32 supports [software pin inversion](https://github.com/bolderflight/sbus#inverted-serial).*
+
+## Schematics
+
+<img src="img/schematics.svg" width=800 alt="Flix schematics">
+
+You can also check a user contributed [variant of complete circuit diagram](https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764574482511443&cot=14) of the drone.
--- a/docs/zoom.css
+++ b/docs/zoom.css
@@ -0,0 +1,31 @@
+img[data-action="zoom"] {
+  cursor: zoom-in;
+}
+.zoom-img,
+.zoom-img-wrap {
+  position: relative;
+  z-index: 666;
+  transition: all 300ms;
+}
+img.zoom-img {
+  cursor: zoom-out;
+}
+.zoom-overlay {
+  cursor: zoom-out;
+  z-index: 420;
+  background: #fff;
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  filter: "alpha(opacity=0)";
+  opacity: 0;
+  transition:      opacity 300ms;
+}
+.zoom-overlay-open .zoom-overlay {
+  filter: "alpha(opacity=100)";
+  opacity: 1;
+}
+
+/*# sourceMappingURL=data:application/json;base64,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 */
--- a/docs/zoom.js
+++ b/docs/zoom.js
@@ -0,0 +1,281 @@
+/* https://github.com/spinningarrow/zoom-vanilla.js
+
+The MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+*/
+
+function () { "use strict";
+	var OFFSET = 80
+
+	// From http://youmightnotneedjquery.com/#offset
+	function offset(element) {
+		var rect = element.getBoundingClientRect()
+		var scrollTop = window.pageYOffset ||
+			document.documentElement.scrollTop ||
+			document.body.scrollTop ||
+			0
+		var scrollLeft = window.pageXOffset ||
+			document.documentElement.scrollLeft ||
+			document.body.scrollLeft ||
+			0
+		return {
+			top: rect.top + scrollTop,
+			left: rect.left + scrollLeft
+		}
+	}
+
+	function zoomListener() {
+		var activeZoom = null
+		var initialScrollPosition = null
+		var initialTouchPosition = null
+
+		function listen() {
+			document.body.addEventListener('click', function (event) {
+				if (event.target.getAttribute('data-action') !== 'zoom' ||
+					event.target.tagName !== 'IMG') return
+
+				zoom(event)
+			})
+		}
+
+		function zoom(event) {
+			event.stopPropagation()
+
+			if (document.body.classList.contains('zoom-overlay-open')) return
+
+			if (event.metaKey || event.ctrlKey) return openInNewWindow()
+
+			closeActiveZoom({ forceDispose: true })
+
+			activeZoom = vanillaZoom(event.target)
+			activeZoom.zoomImage()
+
+			addCloseActiveZoomListeners()
+		}
+
+		function openInNewWindow() {
+			window.open(event.target.getAttribute('data-original') ||
+				event.target.currentSrc ||
+				event.target.src,
+				'_blank')
+		}
+
+		function closeActiveZoom(options) {
+			options = options || { forceDispose: false }
+			if (!activeZoom) return
+
+			activeZoom[options.forceDispose ? 'dispose' : 'close']()
+			removeCloseActiveZoomListeners()
+			activeZoom = null
+		}
+
+		function addCloseActiveZoomListeners() {
+			// todo(fat): probably worth throttling this
+			window.addEventListener('scroll', handleScroll)
+			document.addEventListener('click', handleClick)
+			document.addEventListener('keyup', handleEscPressed)
+			document.addEventListener('touchstart', handleTouchStart)
+			document.addEventListener('touchend', handleClick)
+		}
+
+		function removeCloseActiveZoomListeners() {
+			window.removeEventListener('scroll', handleScroll)
+			document.removeEventListener('keyup', handleEscPressed)
+			document.removeEventListener('click', handleClick)
+			document.removeEventListener('touchstart', handleTouchStart)
+			document.removeEventListener('touchend', handleClick)
+		}
+
+		function handleScroll(event) {
+			if (initialScrollPosition === null) initialScrollPosition = window.pageYOffset
+			var deltaY = initialScrollPosition - window.pageYOffset
+			if (Math.abs(deltaY) >= 40) closeActiveZoom()
+		}
+
+		function handleEscPressed(event) {
+			if (event.keyCode == 27) closeActiveZoom()
+		}
+
+		function handleClick(event) {
+			event.stopPropagation()
+			event.preventDefault()
+			closeActiveZoom()
+		}
+
+		function handleTouchStart(event) {
+			initialTouchPosition = event.touches[0].pageY
+			event.target.addEventListener('touchmove', handleTouchMove)
+		}
+
+		function handleTouchMove(event) {
+			if (Math.abs(event.touches[0].pageY - initialTouchPosition) <= 10) return
+			closeActiveZoom()
+			event.target.removeEventListener('touchmove', handleTouchMove)
+		}
+
+		return { listen: listen }
+	}
+
+	var vanillaZoom = (function () {
+		var fullHeight = null
+		var fullWidth = null
+		var overlay = null
+		var imgScaleFactor = null
+
+		var targetImage = null
+		var targetImageWrap = null
+		var targetImageClone = null
+
+		function zoomImage() {
+			var img = document.createElement('img')
+			img.onload = function () {
+				fullHeight = Number(img.height)
+				fullWidth = Number(img.width)
+				zoomOriginal()
+			}
+			img.src = targetImage.currentSrc || targetImage.src
+		}
+
+		function zoomOriginal() {
+			targetImageWrap = document.createElement('div')
+			targetImageWrap.className = 'zoom-img-wrap'
+			targetImageWrap.style.position = 'absolute'
+			targetImageWrap.style.top = offset(targetImage).top + 'px'
+			targetImageWrap.style.left = offset(targetImage).left + 'px'
+
+			targetImageClone = targetImage.cloneNode()
+			targetImageClone.style.visibility = 'hidden'
+
+			targetImage.style.width = targetImage.offsetWidth + 'px'
+			targetImage.parentNode.replaceChild(targetImageClone, targetImage)
+
+			document.body.appendChild(targetImageWrap)
+			targetImageWrap.appendChild(targetImage)
+
+			targetImage.classList.add('zoom-img')
+			targetImage.setAttribute('data-action', 'zoom-out')
+
+			overlay = document.createElement('div')
+			overlay.className = 'zoom-overlay'
+
+			document.body.appendChild(overlay)
+
+			calculateZoom()
+			triggerAnimation()
+		}
+
+		function calculateZoom() {
+			targetImage.offsetWidth // repaint before animating
+
+			var originalFullImageWidth  = fullWidth
+			var originalFullImageHeight = fullHeight
+
+			var maxScaleFactor = originalFullImageWidth / targetImage.width
+
+			var viewportHeight = window.innerHeight - OFFSET
+			var viewportWidth  = window.innerWidth - OFFSET
+
+			var imageAspectRatio    = originalFullImageWidth / originalFullImageHeight
+			var viewportAspectRatio = viewportWidth / viewportHeight
+
+			if (originalFullImageWidth < viewportWidth && originalFullImageHeight < viewportHeight) {
+				imgScaleFactor = maxScaleFactor
+			} else if (imageAspectRatio < viewportAspectRatio) {
+				imgScaleFactor = (viewportHeight / originalFullImageHeight) * maxScaleFactor
+			} else {
+				imgScaleFactor = (viewportWidth / originalFullImageWidth) * maxScaleFactor
+			}
+		}
+
+		function triggerAnimation() {
+			targetImage.offsetWidth // repaint before animating
+
+			var imageOffset = offset(targetImage)
+			var scrollTop   = window.pageYOffset
+
+			var viewportY = scrollTop + (window.innerHeight / 2)
+			var viewportX = (window.innerWidth / 2)
+
+			var imageCenterY = imageOffset.top + (targetImage.height / 2)
+			var imageCenterX = imageOffset.left + (targetImage.width / 2)
+
+			var translateY = Math.round(viewportY - imageCenterY)
+			var translateX = Math.round(viewportX - imageCenterX)
+
+			var targetImageTransform = 'scale(' + imgScaleFactor + ')'
+			var targetImageWrapTransform =
+				'translate(' + translateX + 'px, ' + translateY + 'px) translateZ(0)'
+
+			targetImage.style.webkitTransform = targetImageTransform
+			targetImage.style.msTransform = targetImageTransform
+			targetImage.style.transform = targetImageTransform
+
+			targetImageWrap.style.webkitTransform = targetImageWrapTransform
+			targetImageWrap.style.msTransform = targetImageWrapTransform
+			targetImageWrap.style.transform = targetImageWrapTransform
+
+			document.body.classList.add('zoom-overlay-open')
+		}
+
+		function close() {
+			document.body.classList.remove('zoom-overlay-open')
+			document.body.classList.add('zoom-overlay-transitioning')
+
+			targetImage.style.webkitTransform = ''
+			targetImage.style.msTransform = ''
+			targetImage.style.transform = ''
+
+			targetImageWrap.style.webkitTransform = ''
+			targetImageWrap.style.msTransform = ''
+			targetImageWrap.style.transform = ''
+
+			if (!'transition' in document.body.style) return dispose()
+
+			targetImageWrap.addEventListener('transitionend', dispose)
+			targetImageWrap.addEventListener('webkitTransitionEnd', dispose)
+		}
+
+		function dispose() {
+			targetImage.removeEventListener('transitionend', dispose)
+			targetImage.removeEventListener('webkitTransitionEnd', dispose)
+
+			if (!targetImageWrap || !targetImageWrap.parentNode) return
+
+			targetImage.classList.remove('zoom-img')
+			targetImage.style.width = ''
+			targetImage.setAttribute('data-action', 'zoom')
+
+			targetImageClone.parentNode.replaceChild(targetImage, targetImageClone)
+			targetImageWrap.parentNode.removeChild(targetImageWrap)
+			overlay.parentNode.removeChild(overlay)
+
+			document.body.classList.remove('zoom-overlay-transitioning')
+		}
+
+		return function (target) {
+			targetImage = target
+			return { zoomImage: zoomImage, close: close, dispose: dispose }
+		}
+	}())
+
+	zoomListener().listen()
+}()
--- a/flix/cli.ino
+++ b/flix/cli.ino
@@ -5,10 +5,12 @@

 #include "pid.h"
 #include "vector.h"
+#include "util.h"

 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
-extern float loopRate;
-extern uint16_t channels[16];
+extern float loopRate, dt;
+extern double t;
+extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;

 const char* motd =
 "\nWelcome to\n"
@@ -20,6 +22,11 @@ const char* motd =
 "|__|     |_______||__| /__/ \\__\\\n\n"
 "Commands:\n\n"
 "help - show help\n"
+"p - show all parameters\n"
+"p <name> - show parameter\n"
+"p <name> <value> - set parameter\n"
+"preset - reset parameters\n"
+"time - show time info\n"
 "ps - show pitch/roll/yaw\n"
 "psq - show attitude quaternion\n"
 "imu - show IMU data\n"
@@ -30,32 +37,88 @@ const char* motd =
 "cg - calibrate gyro\n"
 "ca - calibrate accel\n"
 "mfr, mfl, mrr, mrl - test motor (remove props)\n"
-"reset - reset drone's state\n";
+"reset - reset drone's state\n"
+"reboot - reboot the drone\n";

-void doCommand(const String& command) {
+void print(const char* format, ...) {
+	char buf[1000];
+	va_list args;
+	va_start(args, format);
+	vsnprintf(buf, sizeof(buf), format, args);
+	va_end(args);
+	Serial.print(buf);
+#if WIFI_ENABLED
+	mavlinkPrint(buf);
+#endif
+}
+
+void pause(float duration) {
+#if ARDUINO
+	double start = t;
+	while (t - start < duration) {
+		step();
+		handleInput();
+#if WIFI_ENABLED
+		processMavlink();
+#endif
+	}
+#else
+	// Code above won't work in the simulation
+	delay(duration * 1000);
+#endif
+}
+
+void doCommand(String str, bool echo = false) {
+	// parse command
+	String command, arg0, arg1;
+	splitString(str, command, arg0, arg1);
+
+	// echo command
+	if (echo && !command.isEmpty()) {
+		print("> %s\n", str.c_str());
+	}
+
+	// execute command
 	if (command == "help" || command == "motd") {
-		Serial.println(motd);
+		print("%s\n", motd);
+	} else if (command == "p" && arg0 == "") {
+		printParameters();
+	} else if (command == "p" && arg0 != "" && arg1 == "") {
+		print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
+	} else if (command == "p") {
+		bool success = setParameter(arg0.c_str(), arg1.toFloat());
+		if (success) {
+			print("%s = %g\n", arg0.c_str(), arg1.toFloat());
+		} else {
+			print("Parameter not found: %s\n", arg0.c_str());
+		}
+	} else if (command == "preset") {
+		resetParameters();
+	} else if (command == "time") {
+		print("Time: %f\n", t);
+		print("Loop rate: %f\n", loopRate);
+		print("dt: %f\n", dt);
 	} else if (command == "ps") {
-		Vector a = attitude.toEuler();
-		Serial.printf("roll: %f pitch: %f yaw: %f\n", a.x * RAD_TO_DEG, a.y * RAD_TO_DEG, a.z * RAD_TO_DEG);
+		Vector a = attitude.toEulerZYX();
+		print("roll: %f pitch: %f yaw: %f\n", degrees(a.x), degrees(a.y), degrees(a.z));
 	} else if (command == "psq") {
-		Serial.printf("qx: %f qy: %f qz: %f qw: %f\n", attitude.x, attitude.y, attitude.z, attitude.w);
+		print("qx: %f qy: %f qz: %f qw: %f\n", attitude.x, attitude.y, attitude.z, attitude.w);
 	} else if (command == "imu") {
 		printIMUInfo();
-		Serial.printf("gyro: %f %f %f\n", rates.x, rates.y, rates.z);
-		Serial.printf("acc: %f %f %f\n", acc.x, acc.y, acc.z);
-		printIMUCalibration();
-		Serial.printf("rate: %f\n", loopRate);
+		print("gyro: %f %f %f\n", rates.x, rates.y, rates.z);
+		print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
+		printIMUCal();
+		print("rate: %f\n", loopRate);
 	} else if (command == "rc") {
-		Serial.printf("channels: ");
-		for (int i = 0; i < 16; i++) {
-			Serial.printf("%u ", channels[i]);
-		}
-		Serial.printf("\nroll: %g pitch: %g yaw: %g throttle: %g armed: %g mode: %g\n",
-			controlRoll, controlPitch, controlYaw, controlThrottle, controlArmed, controlMode);
-		Serial.printf("mode: %s\n", getModeName());
+		print("Raw: throttle %d yaw %d pitch %d roll %d armed %d mode %d\n",
+			channels[throttleChannel], channels[yawChannel], channels[pitchChannel],
+			channels[rollChannel], channels[armedChannel], channels[modeChannel]);
+		print("Control: throttle %g yaw %g pitch %g roll %g armed %g mode %g\n",
+			controls[throttleChannel], controls[yawChannel], controls[pitchChannel],
+			controls[rollChannel], controls[armedChannel], controls[modeChannel]);
+		print("Mode: %s\n", getModeName());
 	} else if (command == "mot") {
-		Serial.printf("front-right %f front-left %f rear-right %f rear-left %f\n",
+		print("Motors: 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") {
 		dumpLog();
@@ -75,10 +138,12 @@ void doCommand(const String& command) {
 		testMotor(MOTOR_REAR_LEFT);
 	} else if (command == "reset") {
 		attitude = Quaternion();
+	} else if (command == "reboot") {
+		ESP.restart();
 	} else if (command == "") {
 		// do nothing
 	} else {
-		Serial.println("Invalid command: " + command);
+		print("Invalid command: %s\n", command.c_str());
 	}
 }

@@ -87,7 +152,7 @@ void handleInput() {
 	static String input;

 	if (showMotd) {
-		Serial.printf("%s\n", motd);
+		print("%s\n", motd);
 		showMotd = false;
 	}

--- a/flix/control.ino
+++ b/flix/control.ino
@@ -45,6 +45,8 @@ PID yawRatePID(YAWRATE_P, YAWRATE_I, YAWRATE_D);
 PID rollPID(ROLL_P, ROLL_I, ROLL_D);
 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;

 Quaternion attitudeTarget;
 Vector ratesTarget;
@@ -52,6 +54,7 @@ Vector torqueTarget;
 float thrustTarget;

 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
+extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;

 void control() {
 	interpretRC();
@@ -69,39 +72,39 @@ void control() {
 }

 void interpretRC() {
-	armed = controlThrottle >= 0.05 && controlArmed >= 0.5;
-
+	armed = controls[throttleChannel] >= 0.05 &&
+		(controls[armedChannel] >= 0.5 || isnan(controls[armedChannel])); // assume armed if armed channel is not defined

 	// NOTE: put ACRO or MANUAL modes there if you want to use them
-	if (controlMode < 0.25) {
+	if (controls[modeChannel] < 0.25) {
 		mode = STAB;
-	} else if (controlMode < 0.75) {
+	} else if (controls[modeChannel] < 0.75) {
 		mode = STAB;
 	} else {
 		mode = STAB;
 	}

-	thrustTarget = controlThrottle;
+	thrustTarget = controls[throttleChannel];

 	if (mode == ACRO) {
 		yawMode = YAW_RATE;
-		ratesTarget.x = controlRoll * ROLLRATE_MAX;
-		ratesTarget.y = controlPitch * PITCHRATE_MAX;
-		ratesTarget.z = -controlYaw * YAWRATE_MAX; // positive yaw stick means clockwise rotation in FLU
+		ratesTarget.x = controls[rollChannel] * maxRate.x;
+		ratesTarget.y = controls[pitchChannel] * maxRate.y;
+		ratesTarget.z = -controls[yawChannel] * maxRate.z; // positive yaw stick means clockwise rotation in FLU

 	} else if (mode == STAB) {
-		yawMode = controlYaw == 0 ? YAW : YAW_RATE;
+		yawMode = controls[yawChannel] == 0 ? YAW : YAW_RATE;

-		attitudeTarget = Quaternion::fromEuler(Vector(
-			controlRoll * TILT_MAX,
-			controlPitch * TILT_MAX,
+		attitudeTarget = Quaternion::fromEulerZYX(Vector(
+			controls[rollChannel] * tiltMax,
+			controls[pitchChannel] * tiltMax,
 			attitudeTarget.getYaw()));
-		ratesTarget.z = -controlYaw * YAWRATE_MAX; // positive yaw stick means clockwise rotation in FLU
+		ratesTarget.z = -controls[yawChannel] * maxRate.z; // positive yaw stick means clockwise rotation in FLU

 	} else if (mode == MANUAL) {
 		// passthrough mode
 		yawMode = YAW_RATE;
-		torqueTarget = Vector(controlRoll, controlPitch, -controlYaw) * 0.01;
+		torqueTarget = Vector(controls[rollChannel], controls[pitchChannel], -controls[yawChannel]) * 0.01;
 	}

 	if (yawMode == YAW_RATE || !motorsActive()) {
@@ -119,10 +122,10 @@ void controlAttitude() {
 	}

 	const Vector up(0, 0, 1);
-	Vector upActual = Quaternion::rotateVector(up, attitude);
-	Vector upTarget = Quaternion::rotateVector(up, attitudeTarget);
+	Vector upActual = attitude.rotateVector(up);
+	Vector upTarget = attitudeTarget.rotateVector(up);

-	Vector error = Vector::rotationVectorBetween(upTarget, upActual);
+	Vector error = Vector::angularRatesBetweenVectors(upTarget, upActual);

 	ratesTarget.x = rollPID.update(error.x, dt);
 	ratesTarget.y = pitchPID.update(error.y, dt);
--- a/flix/estimate.ino
+++ b/flix/estimate.ino
@@ -23,7 +23,7 @@ void applyGyro() {
 	rates = ratesFilter.update(gyro);

 	// apply rates to attitude
-	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(rates * dt));
+	attitude = attitude.rotate(Quaternion::fromAngularRates(rates * dt));
 }

 void applyAcc() {
@@ -34,9 +34,9 @@ void applyAcc() {
 	if (!landed) return;

 	// calculate accelerometer correction
-	Vector up = Quaternion::rotateVector(Vector(0, 0, 1), attitude);
-	Vector correction = Vector::rotationVectorBetween(acc, up) * WEIGHT_ACC;
+	Vector up = attitude.rotateVector(Vector(0, 0, 1));
+	Vector correction = Vector::angularRatesBetweenVectors(acc, up) * WEIGHT_ACC;

 	// apply correction
-	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(correction));
+	attitude = attitude.rotate(Quaternion::fromAngularRates(correction));
 }
--- a/flix/failsafe.ino
+++ b/flix/failsafe.ino
@@ -1,16 +1,31 @@
 // Copyright (c) 2024 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix

-// Fail-safe for RC loss
+// Fail-safe functions

 #define RC_LOSS_TIMEOUT 0.2
 #define DESCEND_TIME 3.0 // time to descend from full throttle to zero

-extern float controlTime;
+extern double controlsTime;
+extern int rollChannel, pitchChannel, throttleChannel, yawChannel;
+
+void failsafe() {
+	armingFailsafe();
+	rcLossFailsafe();
+}
+
+// Prevent arming without zero throttle input
+void armingFailsafe() {
+	static double zeroThrottleTime;
+	static double armingTime;
+	if (!armed) armingTime = t; // stores the last time when the drone was disarmed, therefore contains arming time
+	if (controlsTime > 0 && controls[throttleChannel] < 0.05) zeroThrottleTime = controlsTime;
+	if (armingTime - zeroThrottleTime > 0.1) armed = false; // prevent arming if there was no zero throttle for 0.1 sec
+}

 // RC loss failsafe
-void failsafe() {
-	if (t - controlTime > RC_LOSS_TIMEOUT) {
+void rcLossFailsafe() {
+	if (t - controlsTime > RC_LOSS_TIMEOUT) {
 		descend();
 	}
 }
@@ -18,9 +33,9 @@ void failsafe() {
 // Smooth descend on RC lost
 void descend() {
 	mode = STAB;
-	controlRoll = 0;
-	controlPitch = 0;
-	controlYaw = 0;
-	controlThrottle -= dt / DESCEND_TIME;
-	if (controlThrottle < 0) controlThrottle = 0;
+	controls[rollChannel] = 0;
+	controls[pitchChannel] = 0;
+	controls[yawChannel] = 0;
+	controls[throttleChannel] -= dt / DESCEND_TIME;
+	if (controls[throttleChannel] < 0) controls[throttleChannel] = 0;
 }
--- a/flix/flix.ino
+++ b/flix/flix.ino
@@ -10,19 +10,21 @@
 #define SERIAL_BAUDRATE 115200
 #define WIFI_ENABLED 1

-float t = NAN; // current step time, s
+double t = NAN; // current step time, s
 float dt; // time delta from previous step, s
-float controlRoll, controlPitch, controlYaw, controlThrottle, controlArmed, controlMode; // pilot's inputs, range [-1, 1]
+int16_t channels[16]; // raw rc channels
+float controls[16]; // normalized controls in range [-1..1] ([0..1] for throttle)
 Vector gyro; // gyroscope data
 Vector acc; // accelerometer data, m/s/s
 Vector rates; // filtered angular rates, rad/s
 Quaternion attitude; // estimated attitude
-float motors[4]; // normalized motors thrust in range [0..1]
+float motors[4]; // normalized motors thrust in range [-1..1]

 void setup() {
 	Serial.begin(SERIAL_BAUDRATE);
-	Serial.println("Initializing flix\n");
+	print("Initializing flix");
 	disableBrownOut();
+	setupParameters();
 	setupLED();
 	setupMotors();
 	setLED(true);
@@ -32,7 +34,7 @@ void setup() {
 	setupIMU();
 	setupRC();
 	setLED(false);
-	Serial.println("Initializing complete\n");
+	print("Initializing complete");
 }

 void loop() {
@@ -47,4 +49,5 @@ void loop() {
 	processMavlink();
 #endif
 	logData();
+	syncParameters();
 }
--- a/flix/imu.ino
+++ b/flix/imu.ino
@@ -9,21 +9,15 @@

 MPU9250 IMU(SPI);

-// NOTE: use 'ca' command to calibrate the accelerometer and put the values here
 Vector accBias;
-Vector accScale(1, 1, 1);
 Vector gyroBias;
+Vector accScale(1, 1, 1);

 void setupIMU() {
-	Serial.println("Setup IMU");
-	bool status = IMU.begin();
-	if (!status) {
-		while (true) {
-			Serial.println("IMU begin error");
-			delay(1000);
-		}
-	}
+	print("Setup IMU\n");
+	IMU.begin();
 	configureIMU();
+	delay(500); // wait a bit before calibrating
 	calibrateGyro();
 }

@@ -55,7 +49,7 @@ void rotateIMU(Vector& data) {

 void calibrateGyro() {
 	const int samples = 1000;
-	Serial.println("Calibrating gyro, stand still");
+	print("Calibrating gyro, stand still\n");
 	IMU.setGyroRange(IMU.GYRO_RANGE_250DPS); // the most sensitive mode

 	gyroBias = Vector(0, 0, 0);
@@ -66,36 +60,34 @@ void calibrateGyro() {
 	}
 	gyroBias = gyroBias / samples;

-	printIMUCalibration();
+	printIMUCal();
 	configureIMU();
 }

 void calibrateAccel() {
-	Serial.println("Calibrating accelerometer");
+	print("Calibrating accelerometer\n");
 	IMU.setAccelRange(IMU.ACCEL_RANGE_2G); // the most sensitive mode

-	Serial.setTimeout(60000);
-	Serial.print("1/6 Place level [enter] ");
-	Serial.readStringUntil('\n');
+	print("Place level [8 sec]\n");
+	pause(8);
 	calibrateAccelOnce();
-	Serial.print("2/6 Place nose up [enter] ");
-	Serial.readStringUntil('\n');
+	print("Place nose up [8 sec]\n");
+	pause(8);
 	calibrateAccelOnce();
-	Serial.print("3/6 Place nose down [enter] ");
-	Serial.readStringUntil('\n');
+	print("Place nose down [8 sec]\n");
+	pause(8);
 	calibrateAccelOnce();
-	Serial.print("4/6 Place on right side [enter] ");
-	Serial.readStringUntil('\n');
+	print("Place on right side [8 sec]\n");
+	pause(8);
 	calibrateAccelOnce();
-	Serial.print("5/6 Place on left side [enter] ");
-	Serial.readStringUntil('\n');
+	print("Place on left side [8 sec]\n");
+	pause(8);
 	calibrateAccelOnce();
-	Serial.print("6/6 Place upside down [enter] ");
-	Serial.readStringUntil('\n');
+	print("Place upside down [8 sec]\n");
+	pause(8);
 	calibrateAccelOnce();

-	printIMUCalibration();
-	Serial.print("✓ Calibration done!\n");
+	printIMUCal();
 	configureIMU();
 }

@@ -121,18 +113,22 @@ void calibrateAccelOnce() {
 	if (acc.x < accMin.x) accMin.x = acc.x;
 	if (acc.y < accMin.y) accMin.y = acc.y;
 	if (acc.z < accMin.z) accMin.z = acc.z;
+	print("acc %f %f %f\n", acc.x, acc.y, acc.z);
+	print("max %f %f %f\n", accMax.x, accMax.y, accMax.z);
+	print("min %f %f %f\n", accMin.x, accMin.y, accMin.z);
 	// Compute scale and bias
 	accScale = (accMax - accMin) / 2 / ONE_G;
 	accBias = (accMax + accMin) / 2;
 }

-void printIMUCalibration() {
-	Serial.printf("gyro bias: %f %f %f\n", gyroBias.x, gyroBias.y, gyroBias.z);
-	Serial.printf("accel bias: %f %f %f\n", accBias.x, accBias.y, accBias.z);
-	Serial.printf("accel scale: %f %f %f\n", accScale.x, accScale.y, accScale.z);
+void printIMUCal() {
+	print("gyro bias: %f %f %f\n", gyroBias.x, gyroBias.y, gyroBias.z);
+	print("accel bias: %f %f %f\n", accBias.x, accBias.y, accBias.z);
+	print("accel scale: %f %f %f\n", accScale.x, accScale.y, accScale.z);
 }

 void printIMUInfo() {
-	Serial.printf("model: %s\n", IMU.getModel());
-	Serial.printf("who am I: 0x%02X\n", IMU.whoAmI());
+	IMU.status() ? print("status: ERROR %d\n", IMU.status()) : print("status: OK\n");
+	print("model: %s\n", IMU.getModel());
+	print("who am I: 0x%02X\n", IMU.whoAmI());
 }
--- a/flix/led.ino
+++ b/flix/led.ino
@@ -21,3 +21,7 @@ void setLED(bool on) {
 	digitalWrite(LED_BUILTIN, on ? HIGH : LOW);
 	state = on;
 }
+
+void blinkLED() {
+	setLED(micros() / BLINK_PERIOD % 2);
+}
--- a/flix/log.ino
+++ b/flix/log.ino
@@ -3,36 +3,60 @@

 // In-RAM logging

+#include "vector.h"
+
 #define LOG_RATE 100
 #define LOG_DURATION 10
 #define LOG_PERIOD 1.0 / LOG_RATE
 #define LOG_SIZE LOG_DURATION * LOG_RATE
-#define LOG_COLUMNS 14

-float logBuffer[LOG_SIZE][LOG_COLUMNS]; // * 4 (float)
-int logPointer = 0;
+float tFloat;
+Vector attitudeEuler;
+Vector attitudeTargetEuler;
+
+struct LogEntry {
+	const char *name;
+	float *value;
+};
+
+LogEntry logEntries[] = {
+	{"t", &tFloat},
+	{"rates.x", &rates.x},
+	{"rates.y", &rates.y},
+	{"rates.z", &rates.z},
+	{"ratesTarget.x", &ratesTarget.x},
+	{"ratesTarget.y", &ratesTarget.y},
+	{"ratesTarget.z", &ratesTarget.z},
+	{"attitude.x", &attitudeEuler.x},
+	{"attitude.y", &attitudeEuler.y},
+	{"attitude.z", &attitudeEuler.z},
+	{"attitudeTarget.x", &attitudeTargetEuler.x},
+	{"attitudeTarget.y", &attitudeTargetEuler.y},
+	{"attitudeTarget.z", &attitudeTargetEuler.z},
+	{"thrustTarget", &thrustTarget}
+};
+
+const int logColumns = sizeof(logEntries) / sizeof(logEntries[0]);
+float logBuffer[LOG_SIZE][logColumns];
+
+void prepareLogData() {
+	tFloat = t;
+	attitudeEuler = attitude.toEulerZYX();
+	attitudeTargetEuler = attitudeTarget.toEulerZYX();
+}

 void logData() {
 	if (!armed) return;
-
-	static float logTime = 0;
+	static int logPointer = 0;
+	static double logTime = 0;
 	if (t - logTime < LOG_PERIOD) return;
 	logTime = t;

-	logBuffer[logPointer][0] = t;
-	logBuffer[logPointer][1] = rates.x;
-	logBuffer[logPointer][2] = rates.y;
-	logBuffer[logPointer][3] = rates.z;
-	logBuffer[logPointer][4] = ratesTarget.x;
-	logBuffer[logPointer][5] = ratesTarget.y;
-	logBuffer[logPointer][6] = ratesTarget.z;
-	logBuffer[logPointer][7] = attitude.toEuler().x;
-	logBuffer[logPointer][8] = attitude.toEuler().y;
-	logBuffer[logPointer][9] = attitude.toEuler().z;
-	logBuffer[logPointer][10] = attitudeTarget.toEuler().x;
-	logBuffer[logPointer][11] = attitudeTarget.toEuler().y;
-	logBuffer[logPointer][12] = attitudeTarget.toEuler().z;
-	logBuffer[logPointer][13] = thrustTarget;
+	prepareLogData();
+
+	for (int i = 0; i < logColumns; i++) {
+		logBuffer[logPointer][i] = *logEntries[i].value;
+	}

 	logPointer++;
 	if (logPointer >= LOG_SIZE) {
@@ -41,13 +65,15 @@ void logData() {
 }

 void dumpLog() {
-	Serial.printf("t,rates.x,rates.y,rates.z,ratesTarget.x,ratesTarget.y,ratesTarget.z,"
-		"attitude.x,attitude.y,attitude.z,attitudeTarget.x,attitudeTarget.y,attitudeTarget.z,thrustTarget\n");
+	// Print header
+	for (int i = 0; i < logColumns; i++) {
+		print("%s%s", logEntries[i].name, i < logColumns - 1 ? "," : "\n");
+	}
+	// Print data
 	for (int i = 0; i < LOG_SIZE; i++) {
 		if (logBuffer[i][0] == 0) continue; // skip empty records
-		for (int j = 0; j < LOG_COLUMNS - 1; j++) {
-			Serial.printf("%f,", logBuffer[i][j]);
+		for (int j = 0; j < logColumns; j++) {
+			print("%g%s", logBuffer[i][j], j < logColumns - 1 ? "," : "\n");
 		}
-		Serial.printf("%f\n", logBuffer[i][LOG_COLUMNS - 1]);
 	}
 }
--- a/flix/lpf.h
+++ b/flix/lpf.h
@@ -22,8 +22,7 @@ public:
 			output = input;
 			initialized = true;
 		}
-
-		return output += alpha * (input - output);
+		return output = output * (1 - alpha) + input * alpha;
 	}

 	void setCutOffFrequency(float cutOffFreq, float dt) {
--- a/flix/mavlink.ino
+++ b/flix/mavlink.ino
@@ -13,7 +13,10 @@
 #define MAVLINK_CONTROL_SCALE 0.7f
 #define MAVLINK_CONTROL_YAW_DEAD_ZONE 0.1f

-extern float controlTime;
+float mavlinkControlScale = 0.7;
+
+extern double controlsTime;
+extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;

 void processMavlink() {
 	sendMavlink();
@@ -21,8 +24,8 @@ void processMavlink() {
 }

 void sendMavlink() {
-	static float lastSlow = 0;
-	static float lastFast = 0;
+	static double lastSlow = 0;
+	static double lastFast = 0;

 	mavlink_message_t msg;
 	uint32_t time = t * 1000;
@@ -30,8 +33,8 @@ void sendMavlink() {
 	if (t - lastSlow >= PERIOD_SLOW) {
 		lastSlow = t;

-		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
-			MAV_MODE_FLAG_MANUAL_INPUT_ENABLED | (armed * MAV_MODE_FLAG_SAFETY_ARMED) | ((mode == STAB) * MAV_MODE_FLAG_STABILIZE_ENABLED),
+		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR,
+			MAV_AUTOPILOT_GENERIC, MAV_MODE_FLAG_MANUAL_INPUT_ENABLED | (armed ? MAV_MODE_FLAG_SAFETY_ARMED : 0),
 			0, MAV_STATE_STANDBY);
 		sendMessage(&msg);
 	}
@@ -40,12 +43,15 @@ void sendMavlink() {
 		lastFast = t;

 		const float zeroQuat[] = {0, 0, 0, 0};
+		Quaternion attitudeFRD = fluToFrd(attitude); // MAVLink uses FRD coordinate system
 		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
+			time, attitudeFRD.w, attitudeFRD.x, attitudeFRD.y, attitudeFRD.z, rates.x, rates.y, rates.z, zeroQuat);
 		sendMessage(&msg);

-		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);
+		mavlink_msg_rc_channels_scaled_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, controlsTime * 1000, 0,
+			controls[0] * 10000, controls[1] * 10000, controls[2] * 10000,
+			controls[3] * 10000, controls[4] * 10000, controls[5] * 10000,
+			INT16_MAX, INT16_MAX, UINT8_MAX);
 		sendMessage(&msg);

 		float actuator[32];
@@ -54,8 +60,8 @@ void sendMavlink() {
 		sendMessage(&msg);

 		mavlink_msg_scaled_imu_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time,
-			acc.x * 1000, -acc.y * 1000, -acc.z * 1000, // convert to frd
-			gyro.x * 1000, -gyro.y * 1000, -gyro.z * 1000,
+			acc.x * 1000, acc.y * 1000, acc.z * 1000,
+			gyro.x * 1000, gyro.y * 1000, gyro.z * 1000,
 			0, 0, 0, 0);
 		sendMessage(&msg);
 	}
@@ -82,21 +88,126 @@ void receiveMavlink() {
 }

 void handleMavlink(const void *_msg) {
-	const mavlink_message_t& msg = *(mavlink_message_t *)_msg;
+	const mavlink_message_t &msg = *(mavlink_message_t *)_msg;

 	if (msg.msgid == MAVLINK_MSG_ID_MANUAL_CONTROL) {
 		mavlink_manual_control_t m;
 		mavlink_msg_manual_control_decode(&msg, &m);
-		controlThrottle = m.z / 1000.0f;
-		controlPitch = m.x / 1000.0f * MAVLINK_CONTROL_SCALE;
-		controlRoll = m.y / 1000.0f * MAVLINK_CONTROL_SCALE;
-		controlYaw = m.r / 1000.0f * MAVLINK_CONTROL_SCALE;
-		controlMode = 1; // STAB mode
-		controlArmed = 1; // armed
-		controlTime = t;
+		if (m.target && m.target != SYSTEM_ID) return; // 0 is broadcast

-		if (abs(controlYaw) < MAVLINK_CONTROL_YAW_DEAD_ZONE) controlYaw = 0;
+		controls[throttleChannel] = m.z / 1000.0f;
+		controls[pitchChannel] = m.x / 1000.0f * mavlinkControlScale;
+		controls[rollChannel] = m.y / 1000.0f * mavlinkControlScale;
+		controls[yawChannel] = m.r / 1000.0f * mavlinkControlScale;
+		controls[modeChannel] = 1; // STAB mode
+		controls[armedChannel] = 1; // armed
+		controlsTime = t;
+
+		if (abs(controls[yawChannel]) < MAVLINK_CONTROL_YAW_DEAD_ZONE) controls[yawChannel] = 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 != SYSTEM_ID) return;
+
+		mavlink_message_t msg;
+		for (int i = 0; i < parametersCount(); i++) {
+			mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
+				getParameterName(i), getParameter(i), MAV_PARAM_TYPE_REAL32, parametersCount(), i);
+			sendMessage(&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 != 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
+		float value = strlen(name) == 0 ? getParameter(m.param_index) : getParameter(name);
+		if (m.param_index != -1) {
+			memcpy(name, getParameterName(m.param_index), 16);
+		}
+		mavlink_message_t 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);
+	}
+
+	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 != 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
+		setParameter(name, m.param_value);
+		// send ack
+		mavlink_message_t msg;
+		mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
+			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 != SYSTEM_ID) return;
+
+		mavlink_message_t msg;
+		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 != 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
+		doCommand(data, true);
+	}
+
+	// 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 != SYSTEM_ID) return;
+		mavlink_message_t ack;
+		mavlink_message_t response;
+
+		if (m.command == MAV_CMD_REQUEST_MESSAGE && m.param1 == MAVLINK_MSG_ID_AUTOPILOT_VERSION) {
+			mavlink_msg_command_ack_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, MAV_RESULT_ACCEPTED, UINT8_MAX, 0, msg.sysid, msg.compid);
+			sendMessage(&ack);
+			mavlink_msg_autopilot_version_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &response,
+				MAV_PROTOCOL_CAPABILITY_PARAM_FLOAT | MAV_PROTOCOL_CAPABILITY_MAVLINK2, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0);
+			sendMessage(&response);
+		} else {
+			mavlink_msg_command_ack_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, MAV_RESULT_UNSUPPORTED, UINT8_MAX, 0, msg.sysid, msg.compid);
+			sendMessage(&ack);
+		}
 	}
 }

+// Send shell output to GCS
+void mavlinkPrint(const char* str) {
+	// Send data in chunks
+	for (int i = 0; i < strlen(str); i += MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN) {
+		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(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
+			SERIAL_CONTROL_DEV_SHELL, 0, 0, 0, strlen(data), (uint8_t *)data, 0, 0);
+		sendMessage(&msg);
+	}
+}
+
+// Convert Forward-Left-Up to Forward-Right-Down quaternion
+inline Quaternion fluToFrd(const Quaternion &q) {
+	return Quaternion(q.w, q.x, -q.y, -q.z);
+}
+
 #endif
--- a/flix/motors.ino
+++ b/flix/motors.ino
@@ -2,6 +2,7 @@
 // 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"

@@ -10,8 +11,11 @@
 #define MOTOR_2_PIN 14 // front right
 #define MOTOR_3_PIN 15 // front left

-#define PWM_FREQUENCY 78000
-#define PWM_RESOLUTION 10
+#define PWM_FREQUENCY 1000
+#define PWM_RESOLUTION 12
+#define PWM_STOP 0
+#define PWM_MIN 0
+#define PWM_MAX 1000000 / PWM_FREQUENCY

 // Motors array indexes:
 const int MOTOR_REAR_LEFT = 0;
@@ -20,7 +24,7 @@ const int MOTOR_FRONT_RIGHT = 2;
 const int MOTOR_FRONT_LEFT = 3;

 void setupMotors() {
-	Serial.println("Setup Motors");
+	print("Setup Motors\n");

 	// configure pins
 	ledcAttach(MOTOR_0_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
@@ -29,12 +33,14 @@ void setupMotors() {
 	ledcAttach(MOTOR_3_PIN, PWM_FREQUENCY, PWM_RESOLUTION);

 	sendMotors();
-	Serial.println("Motors initialized");
+	print("Motors initialized\n");
 }

 int getDutyCycle(float value) {
 	value = constrain(value, 0, 1);
-	float duty = mapff(value, 0, 1, 0, (1 << PWM_RESOLUTION) - 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);
 }

@@ -49,13 +55,13 @@ bool motorsActive() {
 	return motors[0] != 0 || motors[1] != 0 || motors[2] != 0 || motors[3] != 0;
 }

-void testMotor(int n) {
-	Serial.printf("Testing motor %d\n", n);
+void testMotor(uint8_t 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();
-	delay(3000);
+	pause(3);
 	motors[n] = 0;
 	sendMotors();
-	Serial.printf("Done\n");
+	print("Done\n");
 }
--- a/flix/parameters.ino
+++ b/flix/parameters.ino
@@ -0,0 +1,145 @@
+// Copyright (c) 2024 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Parameters storage in flash memory
+
+#include <Preferences.h>
+
+extern float channelNeutral[16];
+extern float channelMax[16];
+extern float mavlinkControlScale;
+
+Preferences storage;
+
+struct Parameter {
+	const char *name;
+	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},
+	{"GYRO_BIAS_X", &gyroBias.x},
+	{"GYRO_BIAS_Y", &gyroBias.y},
+	{"GYRO_BIAS_Z", &gyroBias.z},
+	// rc
+	{"RC_NEUTRAL_0", &channelNeutral[0]},
+	{"RC_NEUTRAL_1", &channelNeutral[1]},
+	{"RC_NEUTRAL_2", &channelNeutral[2]},
+	{"RC_NEUTRAL_3", &channelNeutral[3]},
+	{"RC_NEUTRAL_4", &channelNeutral[4]},
+	{"RC_NEUTRAL_5", &channelNeutral[5]},
+	{"RC_NEUTRAL_6", &channelNeutral[6]},
+	{"RC_NEUTRAL_7", &channelNeutral[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]},
+#if WIFI_ENABLED
+	// MAVLink
+	{"MAV_CTRL_SCALE", &mavlinkControlScale},
+#endif
+};
+
+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 double 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();
+}
--- a/flix/quaternion.h
+++ b/flix/quaternion.h
@@ -15,22 +15,22 @@ public:

 	Quaternion(float w, float x, float y, float z): w(w), x(x), y(y), z(z) {};

-	static Quaternion fromAxisAngle(const Vector& axis, float angle) {
+	static Quaternion fromAxisAngle(float a, float b, float c, float angle) {
 		float halfAngle = angle * 0.5;
 		float sin2 = sin(halfAngle);
 		float cos2 = cos(halfAngle);
-		float sinNorm = sin2 / axis.norm();
-		return Quaternion(cos2, axis.x * sinNorm, axis.y * sinNorm, axis.z * sinNorm);
+		float sinNorm = sin2 / sqrt(a * a + b * b + c * c);
+		return Quaternion(cos2, a * sinNorm, b * sinNorm, c * sinNorm);
 	}

-	static Quaternion fromRotationVector(const Vector& rotation) {
-		if (rotation.zero()) {
+	static Quaternion fromAngularRates(const Vector& rates) {
+		if (rates.zero()) {
 			return Quaternion();
 		}
-		return Quaternion::fromAxisAngle(rotation, rotation.norm());
+		return Quaternion::fromAxisAngle(rates.x, rates.y, rates.z, rates.norm());
 	}

-	static Quaternion fromEuler(const Vector& euler) {
+	static Quaternion fromEulerZYX(const Vector& euler) {
 		float cx = cos(euler.x / 2);
 		float cy = cos(euler.y / 2);
 		float cz = cos(euler.z / 2);
@@ -60,38 +60,14 @@ public:
 		return ret;
 	}

-	bool finite() const {
-		return isfinite(w) && isfinite(x) && isfinite(y) && isfinite(z);
-	}
-
-	float norm() const {
-		return sqrt(w * w + x * x + y * y + z * z);
-	}
-
-	void normalize() {
-		float n = norm();
-		w /= n;
-		x /= n;
-		y /= n;
-		z /= n;
-	}
-
-	void toAxisAngle(Vector& axis, float& angle) const {
+	void toAxisAngle(float& a, float& b, float& c, float& angle) const {
 		angle = acos(w) * 2;
-		axis.x = x / sin(angle / 2);
-		axis.y = y / sin(angle / 2);
-		axis.z = z / sin(angle / 2);
+		a = x / sin(angle / 2);
+		b = y / sin(angle / 2);
+		c = z / sin(angle / 2);
 	}

-	Vector toRotationVector() const {
-		if (w == 1 && x == 0 && y == 0 && z == 0) return Vector(0, 0, 0); // neutral quaternion
-		float angle;
-		Vector axis;
-		toAxisAngle(axis, angle);
-		return angle * axis;
-	}
-
-	Vector toEuler() const {
+	Vector toEulerZYX() const {
 		// https://github.com/ros/geometry2/blob/589caf083cae9d8fae7effdb910454b4681b9ec1/tf2/include/tf2/impl/utils.h#L87
 		Vector euler;
 		float sqx = x * x;
@@ -136,9 +112,18 @@ public:

 	void setYaw(float yaw) {
 		// TODO: optimize?
-		Vector euler = toEuler();
+		Vector euler = toEulerZYX();
 		euler.z = yaw;
-		(*this) = Quaternion::fromEuler(euler);
+		(*this) = Quaternion::fromEulerZYX(euler);
+	}
+
+	Quaternion& operator *= (const Quaternion& q) {
+		Quaternion ret(
+			w * q.w - x * q.x - y * q.y - z * q.z,
+			w * q.x + x * q.w + y * q.z - z * q.y,
+			w * q.y + y * q.w + z * q.x - x * q.z,
+			w * q.z + z * q.w + x * q.y - y * q.x);
+		return (*this = ret);
 	}

 	Quaternion operator * (const Quaternion& q) const {
@@ -149,14 +134,6 @@ public:
 			w * q.z + z * q.w + x * q.y - y * q.x);
 	}

-	bool operator == (const Quaternion& q) const {
-		return w == q.w && x == q.x && y == q.y && z == q.z;
-	}
-
-	bool operator != (const Quaternion& q) const {
-		return !(*this == q);
-	}
-
 	Quaternion inversed() const {
 		float normSqInv = 1 / (w * w + x * x + y * y + z * z);
 		return Quaternion(
@@ -166,6 +143,18 @@ public:
 			-z * normSqInv);
 	}

+	float norm() const {
+		return sqrt(w * w + x * x + y * y + z * z);
+	}
+
+	void normalize() {
+		float n = norm();
+		w /= n;
+		x /= n;
+		y /= n;
+		z /= n;
+	}
+
 	Vector conjugate(const Vector& v) const {
 		Quaternion qv(0, v.x, v.y, v.z);
 		Quaternion res = (*this) * qv * inversed();
@@ -178,27 +167,22 @@ public:
 		return Vector(res.x, res.y, res.z);
 	}

+	// Rotate vector by quaternion
+	Vector rotateVector(const Vector& v) const {
+		return conjugateInversed(v);
+	}
+
 	// Rotate quaternion by quaternion
-	static Quaternion rotate(const Quaternion& a, const Quaternion& b, const bool normalize = true) {
-		Quaternion rotated = a * b;
+	Quaternion rotate(const Quaternion& q, const bool normalize = true) const {
+		Quaternion rotated = (*this) * q;
 		if (normalize) {
 			rotated.normalize();
 		}
 		return rotated;
 	}

-	// Rotate vector by quaternion
-	static Vector rotateVector(const Vector& v, const Quaternion& q) {
-		return q.conjugateInversed(v);
-	}
-
-	// Quaternion between two quaternions a and b
-	static Quaternion between(const Quaternion& a, const Quaternion& b, const bool normalize = true) {
-		Quaternion q = a * b.inversed();
-		if (normalize) {
-			q.normalize();
-		}
-		return q;
+	bool finite() const {
+		return isfinite(w) && isfinite(x) && isfinite(y) && isfinite(z);
 	}

 	size_t printTo(Print& p) const {
--- a/flix/rc.ino
+++ b/flix/rc.ino
@@ -8,15 +8,7 @@

 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
-
-
-// NOTE: use 'cr' command to calibrate the RC and put the values here
-int channelZero[] = {992, 992, 172, 992, 172, 172, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-int channelMax[] = {1811, 1811, 1811, 1811, 1811, 1811, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-
-// Channels mapping:
+// RC channels mapping:
 int rollChannel = 0;
 int pitchChannel = 1;
 int throttleChannel = 2;
@@ -24,57 +16,54 @@ int yawChannel = 3;
 int armedChannel = 4;
 int modeChannel = 5;

+double controlsTime; // time of the last controls update
+float channelNeutral[16] = {NAN}; // first element NAN means not calibrated
+float channelMax[16];
+
 void setupRC() {
-	Serial.println("Setup RC");
+	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
+		memcpy(channels, data.ch, sizeof(channels)); // copy channels data
 		normalizeRC();
-		controlTime = t;
+		controlsTime = 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);
+	if (isnan(channelNeutral[0])) return; // skip if not calibrated
+	for (uint8_t i = 0; i < 16; i++) {
+		controls[i] = mapf(channels[i], channelNeutral[i], channelMax[i], 0, 1);
 	}
-	// Update control values
-	controlRoll = controls[rollChannel];
-	controlPitch = controls[pitchChannel];
-	controlYaw = controls[yawChannel];
-	controlThrottle = controls[throttleChannel];
-	controlArmed = controls[armedChannel];
-	controlMode = controls[modeChannel];
 }

 void calibrateRC() {
-	Serial.println("Calibrate RC: move all sticks to maximum positions [4 sec]");
-	Serial.println("··o     ··o\n···     ···\n···     ···");
-	delay(4000);
+	print("Calibrate RC: move all sticks to maximum positions [4 sec]\n");
+	print("··o     ··o\n···     ···\n···     ···\n");
+	pause(4);
 	while (!readRC());
 	for (int i = 0; i < 16; i++) {
 		channelMax[i] = channels[i];
 	}
-	Serial.println("Calibrate RC: move all sticks to neutral positions [4 sec]");
-	Serial.println("···     ···\n···     ·o·\n·o·     ···");
-	delay(4000);
+	print("Calibrate RC: move all sticks to neutral positions [4 sec]\n");
+	print("···     ···\n···     ·o·\n·o·     ···\n");
+	pause(4);
 	while (!readRC());
 	for (int i = 0; i < 16; i++) {
-		channelZero[i] = channels[i];
+		channelNeutral[i] = channels[i];
 	}
-	printRCCalibration();
+	printRCCal();
 }

-void printRCCalibration() {
-	for (int i = 0; i < sizeof(channelZero) / sizeof(channelZero[0]); i++) Serial.printf("%d ", channelZero[i]);
-	Serial.printf("\n");
-	for (int i = 0; i < sizeof(channelMax) / sizeof(channelMax[0]); i++) Serial.printf("%d ", channelMax[i]);
-	Serial.printf("\n");
+void printRCCal() {
+	for (int i = 0; i < sizeof(channelNeutral) / sizeof(channelNeutral[0]); i++) print("%g ", channelNeutral[i]);
+	print("\n");
+	for (int i = 0; i < sizeof(channelMax) / sizeof(channelMax[0]); i++) print("%g ", channelMax[i]);
+	print("\n");
 }
--- a/flix/time.ino
+++ b/flix/time.ino
@@ -6,7 +6,7 @@
 float loopRate; // Hz

 void step() {
-	float now = micros() / 1000000.0;
+	double now = micros() / 1000000.0;
 	dt = now - t;
 	t = now;

@@ -18,7 +18,7 @@ void step() {
 }

 void computeLoopRate() {
-	static float windowStart = 0;
+	static double windowStart = 0;
 	static uint32_t rate = 0;
 	rate++;
 	if (t - windowStart >= 1) { // 1 second window
--- a/flix/util.h
+++ b/flix/util.h
@@ -34,3 +34,13 @@ float wrapAngle(float angle) {
 void disableBrownOut() {
 	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA);
 }
+
+// Trim and split string by spaces
+void splitString(String& str, String& token0, String& token1, String& token2) {
+	str.trim();
+	char chars[str.length() + 1];
+	str.toCharArray(chars, str.length() + 1);
+	token0 = strtok(chars, " ");
+	token1 = strtok(NULL, " "); // String(NULL) creates empty string
+	token2 = strtok(NULL, "");
+}
--- a/flix/vector.h
+++ b/flix/vector.h
@@ -13,18 +13,14 @@ public:

 	Vector(float x, float y, float z): x(x), y(y), z(z) {};

-	bool zero() const {
-		return x == 0 && y == 0 && z == 0;
-	}
-
-	bool finite() const {
-		return isfinite(x) && isfinite(y) && isfinite(z);
-	}
-
 	float norm() const {
 		return sqrt(x * x + y * y + z * z);
 	}

+	bool zero() const {
+		return x == 0 && y == 0 && z == 0;
+	}
+
 	void normalize() {
 		float n = norm();
 		x /= n;
@@ -32,10 +28,6 @@ public:
 		z /= n;
 	}

-	Vector operator + (const float b) const {
-		return Vector(x + b, y + b, z + b);
-	}
-
 	Vector operator * (const float b) const {
 		return Vector(x * b, y * b, z * b);
 	}
@@ -52,14 +44,6 @@ public:
 		return Vector(x - b.x, y - b.y, z - b.z);
 	}

-	Vector& operator += (const Vector& b) {
-		return *this = *this + b;
-	}
-
-	Vector& operator -= (const Vector& b) {
-		return *this = *this - b;
-	}
-
 	// Element-wise multiplication
 	Vector operator * (const Vector& b) const {
 		return Vector(x * b.x, y * b.y, z * b.z);
@@ -78,6 +62,10 @@ public:
 		return !(*this == b);
 	}

+	bool finite() const {
+		return isfinite(x) && isfinite(y) && isfinite(z);
+	}
+
 	static float dot(const Vector& a, const Vector& b) {
 		return a.x * b.x + a.y * b.y + a.z * b.z;
 	}
@@ -86,18 +74,18 @@ public:
 		return Vector(a.y * b.z - a.z * b.y, a.z * b.x - a.x * b.z, a.x * b.y - a.y * b.x);
 	}

-	static float angleBetween(const Vector& a, const Vector& b) {
+	static float angleBetweenVectors(const Vector& a, const Vector& b) {
 		return acos(constrain(dot(a, b) / (a.norm() * b.norm()), -1, 1));
 	}

-	static Vector rotationVectorBetween(const Vector& a, const Vector& b) {
+	static Vector angularRatesBetweenVectors(const Vector& a, const Vector& b) {
 		Vector direction = cross(a, b);
 		if (direction.zero()) {
 			// vectors are opposite, return any perpendicular vector
 			return cross(a, Vector(1, 0, 0));
 		}
 		direction.normalize();
-		float angle = angleBetween(a, b);
+		float angle = angleBetweenVectors(a, b);
 		return direction * angle;
 	}

@@ -108,6 +96,3 @@ public:
 			p.print(z, 15);
 	}
 };
-
-Vector operator * (const float a, const Vector& b) { return b * a; }
-Vector operator + (const float a, const Vector& b) { return b + a; }
--- a/flix/wifi.ino
+++ b/flix/wifi.ino
@@ -11,19 +11,20 @@

 #define WIFI_SSID "flix"
 #define WIFI_PASSWORD "flixwifi"
+#define WIFI_UDP_IP "255.255.255.255"
 #define WIFI_UDP_PORT 14550
-#define WIFI_UDP_REMOTE_PORT 14550

 WiFiUDP udp;

 void setupWiFi() {
-	Serial.println("Setup Wi-Fi");
+	print("Setup Wi-Fi\n");
 	WiFi.softAP(WIFI_SSID, WIFI_PASSWORD);
 	udp.begin(WIFI_UDP_PORT);
 }

 void sendWiFi(const uint8_t *buf, int len) {
-	udp.beginPacket(WiFi.softAPBroadcastIP(), WIFI_UDP_REMOTE_PORT);
+	if (WiFi.softAPIP() == IPAddress(0, 0, 0, 0) && WiFi.status() != WL_CONNECTED) return;
+	udp.beginPacket(WIFI_UDP_IP, WIFI_UDP_PORT);
 	udp.write(buf, len);
 	udp.endPacket();
 }
--- a/gazebo/Arduino.h
+++ b/gazebo/Arduino.h
@@ -27,15 +27,31 @@ long map(long x, long in_min, long in_max, long out_min, long out_max) {
 	return (delta * rise) / run + out_min;
 }

+size_t strlcpy(char* dst, const char* src, size_t len) {
+	size_t l = strlen(src);
+	size_t i = 0;
+	while (i < len - 1 && *src != '\0') { *dst++ = *src++; i++; }
+	*dst = '\0';
+	return l;
+}
+
 class __FlashStringHelper;

 // Arduino String partial implementation
 // https://www.arduino.cc/reference/en/language/variables/data-types/stringobject/
 class String: public std::string {
 public:
+	String(const char *str = "") : std::string(str ? str : "") {}
 	long toInt() const { return atol(this->c_str()); }
 	float toFloat() const { return atof(this->c_str()); }
 	bool isEmpty() const { return this->empty(); }
+	void toCharArray(char *buf, unsigned int bufsize, unsigned int index = 0) const {
+		strlcpy(buf, this->c_str() + index, bufsize);
+	}
+	void trim() {
+		this->erase(0, this->find_first_not_of(" \t\n\r"));
+		this->erase(this->find_last_not_of(" \t\n\r") + 1);
+	}
 };

 class Print;
@@ -129,6 +145,11 @@ public:

 HardwareSerial Serial, Serial2;

+class EspClass {
+public:
+	void restart() { Serial.println("Ignore reboot in simulation"); }
+} ESP;
+
 void delay(uint32_t ms) {
 	std::this_thread::sleep_for(std::chrono::milliseconds(ms));
 }
--- a/gazebo/Preferences.h
+++ b/gazebo/Preferences.h
@@ -0,0 +1,61 @@
+// Copyright (c) 2024 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Partial implementation of the ESP32 Preferences library for the simulation
+
+#include <map>
+#include <fstream>
+#include "util.h"
+
+class Preferences {
+private:
+	std::map<std::string, float> storage;
+	std::string storagePath;
+
+	void readFromFile() {
+		std::ifstream file(storagePath);
+		std::string key;
+		float value;
+		while (file >> key >> value) {
+			storage[key] = value;
+		}
+	}
+
+	void writeToFile() {
+		std::ofstream file(storagePath);
+		for (auto &pair : storage) {
+			file << pair.first << " " << pair.second << std::endl;
+		}
+	}
+
+public:
+	bool begin(const char *name, bool readOnly = false, const char *partition_label = NULL) {
+		storagePath = getPluginPath().parent_path() / (std::string(name) + ".txt");
+		gzmsg << "Preferences initialized: " << storagePath << std::endl;
+		readFromFile();
+		return true;
+	}
+
+	bool isKey(const char *key) {
+		return storage.find(key) != storage.end();
+	}
+
+	size_t putFloat(const char *key, float value) {
+		storage[key] = value;
+		writeToFile();
+		return sizeof(value);
+	}
+
+	float getFloat(const char *key, float defaultValue = NAN) {
+		if (!isKey(key)) {
+			return defaultValue;
+		}
+		return storage[key];
+	}
+
+	bool clear() {
+		storage.clear();
+		writeToFile();
+		return true;
+	}
+};
--- a/gazebo/SBUS.h
+++ b/gazebo/SBUS.h
@@ -18,9 +18,6 @@ public:
 	SBUSData data() {
 		SBUSData data;
 		joystickGet(data.ch);
-		for (int i = 0; i < 16; i++) {
-			data.ch[i] = map(data.ch[i], -32768, 32767, 1000, 2000); // convert to pulse width style
-		}
 		return data;
 	};
 };
--- a/gazebo/flix.h
+++ b/gazebo/flix.h
@@ -12,16 +12,18 @@

 #define WIFI_ENABLED 1

-float t = NAN;
+double t = NAN;
 float dt;
 float motors[4];
-float controlRoll, controlPitch, controlYaw, controlThrottle, controlArmed, controlMode;
+int16_t channels[16]; // raw rc channels
+float controls[16];
 Vector acc;
 Vector gyro;
 Vector rates;
 Quaternion attitude;

 // declarations
+void step();
 void computeLoopRate();
 void applyGyro();
 void applyAcc();
@@ -30,24 +32,41 @@ void interpretRC();
 void controlAttitude();
 void controlRate();
 void controlTorque();
-void showTable();
+const char* getModeName();
 void sendMotors();
 bool motorsActive();
-void doCommand(const String& command);
+void testMotor(uint8_t n);
+void print(const char* format, ...);
+void pause(float duration);
+void doCommand(String str, bool echo);
+void handleInput();
+void calibrateRC();
 void normalizeRC();
-void printRCCalibration();
+void printRCCal();
+void dumpLog();
 void processMavlink();
 void sendMavlink();
 void sendMessage(const void *msg);
 void receiveMavlink();
 void handleMavlink(const void *_msg);
-void failsafe();
-void descend();
+void mavlinkPrint(const char* str);
 inline Quaternion fluToFrd(const Quaternion &q);
+void failsafe();
+void armingFailsafe();
+void rcLossFailsafe();
+void descend();
+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 printParameters();
+void resetParameters();

 // mocks
 void setLED(bool on) {};
-void calibrateGyro() { printf("Skip gyro calibrating\n"); };
-void calibrateAccel() { printf("Skip accel calibrating\n"); };
-void printIMUCalibration() { printf("cal: N/A\n"); };
+void calibrateGyro() { print("Skip gyro calibrating\n"); };
+void calibrateAccel() { print("Skip accel calibrating\n"); };
+void printIMUCal() { print("cal: N/A\n"); };
 void printIMUInfo() {};
+Vector accBias, gyroBias, accScale(1, 1, 1);
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Oleg Kalachev	3fdebf39d8	Fix mavlink disconnection in pauses in cli commands Implement pause function that proceeds processing mavlink. Use temporal workaround for simulation, as micros function gives the same result on the same simulation step.	2025-02-28 19:25:41 +03:00
Oleg Kalachev	5bf2e06c5a	Use natural order of ino files includes in simulation In Arduino, ino files are included in alphabetical order. Cleanup unused function declarations in simulation, add missing. Rename flu to frd function to match the code style.	2025-02-28 19:06:58 +03:00
Oleg Kalachev	4e3e8c70b0	Update main book illustration	2025-02-28 03:17:09 +03:00
Oleg Kalachev	bda44fca02	Remove dt multiplier from acc correction and increase acc weight More classical complementary filter implementation Increase effective accelerometer weight for faster convergence	2025-02-28 00:51:16 +03:00
Oleg Kalachev	e66f6563a5	Add custom Wi-Fi control description by @pavelkabakov #11 Co-authored-by: Pavel Kabakov <110939392+pavelkabakov@users.noreply.github.com>	2025-02-26 01:08:36 +03:00
Oleg Kalachev	95084c167c	Add user project by jeka_chex	2025-02-26 00:55:14 +03:00
Oleg Kalachev	931b2066bb	Minor book fix	2025-02-26 00:20:50 +03:00
Oleg Kalachev	a2cf318189	Check target system id in mavlink messages Skip messages addressed to other systems	2025-02-26 00:08:23 +03:00
Oleg Kalachev	83a8dcd63e	Cleanup mavlink subsystem code	2025-02-24 13:06:38 +03:00
Oleg Kalachev	c62e536b50	Put last control time in RC control mavlink message instead of send time	2025-02-22 20:07:26 +03:00
Oleg Kalachev	287a4b5a71	Fix accel calibration via mavlink console Add 5 s timeout as waiting for enter is not implemented for mavlink console yet	2025-02-18 13:01:44 +03:00
Oleg Kalachev	d60628e14d	Support MAVLink console Implement receiving and sending SERIAL_CONTROL message Use global defined print function instead of Serial.printf	2025-02-18 10:33:01 +03:00
Oleg Kalachev	bfef7bd26a	Remove non-nessesary printArray function	2025-02-18 10:26:59 +03:00
Oleg Kalachev	e3c6a0d4df	Make some clarifications regarding imu check in troubleshooting	2025-02-18 10:18:27 +03:00
Oleg Kalachev	9566a4a503	Add parameters access method to build article	2025-02-18 10:14:39 +03:00
Oleg Kalachev	e54e0e8c48	Make all the basic functionality work without the imu	2025-02-17 19:44:18 +03:00
Oleg Kalachev	149c62568f	Refactor CLI submodule Move command parsing to doCommand Parse command with splitString instead of stringToken Trim commands Move cliTestMotor to the bottom Rename parseInput to handleInput, which is more clear Move motor test function to motors.ino	2025-02-17 15:51:58 +03:00
Oleg Kalachev	641e711e67	Minor fix in joystick support for simulation Don't use channels variable as it breaks code isolation	2025-02-15 03:29:09 +03:00
Oleg Kalachev	f2171f2db4	Minor clarification in RC receiver connection table	2025-02-12 11:10:04 +03:00
Oleg Kalachev	6ed6ef3e8c	Assume armed is true if armed channel is not defined	2025-02-12 10:15:42 +03:00
Oleg Kalachev	083db659c6	Improve RC reading in calibration process	2025-02-12 10:15:13 +03:00
Oleg Kalachev	ce1223e82d	Allow CI simulator build under macOS if manually triggered	2025-02-12 06:24:51 +03:00
Peter A. Ukhov	437ce81a68	Add video for flix2 by Peter Ukhov (#10 ) Co-authored-by: Oleg Kalachev <okalachev@gmail.com>	2025-02-12 05:01:56 +03:00
Oleg Kalachev	42f318c6df	Another update of hall of fame page	2025-02-11 14:02:15 +03:00
Oleg Kalachev	1450c793b7	Update hall of fame page	2025-02-11 12:11:22 +03:00
Oleg Kalachev	3ed4143ba0	Simplify WIFI_ENABLED macro test	2025-02-08 02:41:09 +03:00
Oleg Kalachev	33adf33f0e	Add proper command to install arduino-cli on Linux in instructions	2025-02-01 22:56:09 +03:00
Oleg Kalachev	373c0f117a	Update user builds page	2025-01-31 11:15:57 +03:00
Oleg Kalachev	0cb2eb5fac	Update upload-artifact action to fix build	2025-01-31 03:32:09 +03:00
Oleg Kalachev	70f63bfbe9	Add hall of fame page	2025-01-31 03:19:49 +03:00
Oleg Kalachev	15fbe34d19	Add failsafe to prevent arming without prior zero throttle	2025-01-24 16:23:59 +03:00
Zatupitel	7d2d54a94d	Fix working on ESP32-S3 (#8 ) Disable brown-out detector in a more correct way: clear only enable bit instead of clearing the whole register. --------- Co-authored-by: Oleg Kalachev <okalachev@gmail.com>	2025-01-24 14:35:44 +03:00
Oleg Kalachev	60fbe1c450	Fix firmware build with Wi-Fi disabled	2025-01-24 13:50:07 +03:00
Oleg Kalachev	40043768fe	Add test on building the firmware without Wi-Fi to Actions	2025-01-24 13:40:27 +03:00
Oleg Kalachev	dcfe39f8c9	Move SBUS RC declaration to the top	2025-01-24 12:10:48 +03:00
Oleg Kalachev	b2100d10da	Add motors voltage notice in troubleshooting article	2025-01-23 15:03:19 +03:00
Oleg Kalachev	fd6bc42e9e	Fix critical typo in RC loss fail-safe	2025-01-23 00:34:59 +03:00
Oleg Kalachev	c01bac0d0a	Update Flix image for frame version 1.1	2025-01-22 22:11:59 +03:00
Oleg Kalachev	f65c668ca1	Add brief assembly guide article	2025-01-22 01:44:31 +03:00
Oleg Kalachev	64cf5929e2	Add new frame models Version 1.1	2025-01-22 01:42:42 +03:00
Oleg Kalachev	a9e5b2d5ca	Add board pin names for motors to readme	2025-01-21 23:42:28 +03:00
Oleg Kalachev	6028b8a617	Catch port bind error in simulation	2025-01-17 17:38:47 +03:00
Oleg Kalachev	b19270f14e	Minor cleanups and fixes	2025-01-17 12:30:12 +03:00
Oleg Kalachev	740121a88e	Check if requested parameters indexes are correct In case if gcs gets crazy and requests incorrect parameter index	2025-01-14 21:14:04 +03:00
Oleg Kalachev	b915e47f33	Add instructions on using USB remote control via QGroundControl app	2025-01-14 15:07:02 +03:00
Oleg Kalachev	7effd92043	Make MAVLink control scale a parameter	2025-01-14 14:51:34 +03:00
Oleg Kalachev	26bb4d2b3f	Add link to working iOS QGroundControl build	2025-01-13 04:23:19 +03:00
Oleg Kalachev	70f5186c1b	Use double for storing time instead of float Float precision may be not enough after some time of operating	2025-01-12 19:58:36 +03:00
Oleg Kalachev	d4e04c46cd	Add time command to cli	2025-01-12 19:50:00 +03:00
Oleg Kalachev	48d21a911f	Add missing const qualifiers	2025-01-12 19:46:50 +03:00
Oleg Kalachev	f456e10177	Increase motors PWM frequency to 1000 To match the main loop frequency	2025-01-12 15:35:05 +03:00
Oleg Kalachev	ac54c954aa	Cleanup	2025-01-11 04:31:53 +03:00
Oleg Kalachev	9e4a2c5ffc	Move controlsTime variable to rc.ino	2025-01-11 00:28:31 +03:00
Oleg Kalachev	7bf5ee330b	Add link to contributed circuit diagram to readme	2025-01-10 10:52:31 +03:00
Oleg Kalachev	b9e30be98c	Better support for ESCs, add PWM_STOP parameter	2025-01-10 10:49:40 +03:00
Oleg Kalachev	821e6b105e	Make channels definition to rc.ino It's also planned to parametrize them later	2025-01-10 09:37:48 +03:00
Oleg Kalachev	568f9dd5b1	Minor code improvements	2025-01-10 08:59:09 +03:00
Oleg Kalachev	698cc3d9b8	Global variables cleanups Remove unused PID objects for cli Move loopRate to time.ino	2025-01-10 07:10:30 +03:00
Oleg Kalachev	85172cdcc8	Make util module header instead of .ino-file	2025-01-10 06:51:14 +03:00
Oleg Kalachev	08b14d1d76	Minor cleanup	2025-01-10 06:04:32 +03:00
Oleg Kalachev	95824e3b75	Make max tilt and max angle rates MAVLink parameters Also decrease default max yaw rate to 300 degrees	2025-01-10 06:00:06 +03:00
Oleg Kalachev	0a45614751	Move `motorsActive` function to motors.ino	2025-01-09 11:30:04 +03:00
Oleg Kalachev	c8109af04f	Make ONE_G definition const and move to utils.ino	2025-01-09 11:24:40 +03:00
Oleg Kalachev	404ceed851	Make motor indexes definition const int and move them to motors.ino Remove motor indexes definitions from flix.ino Add motors.ino to simulation code and implement required mocks	2025-01-09 11:14:18 +03:00
Oleg Kalachev	72033cdd75	Increase motors PWM resolution to 12 bits	2025-01-09 11:02:38 +03:00
Oleg Kalachev	3088ade743	Fix getDutyCycle return type to make it possible to increase resolution	2025-01-09 11:02:21 +03:00
Oleg Kalachev	c2a9d36d4e	Add small delay before gyro calibration	2025-01-09 10:06:15 +03:00
Oleg Kalachev	ca409396c7	Add missing const qualifiers to some quaternion methods	2025-01-09 10:02:53 +03:00
Oleg Kalachev	ca032abc03	Implement `rotate` method for quaternions as replace for multiplication Vector rotating method is renamed from `rotate` to `rotateVector` to avoid inconsistent object and argument order in different `rotate` methods	2025-01-09 09:56:49 +03:00
Oleg Kalachev	5d10446aaf	Bring back possibility to use ESCs for motors	2025-01-09 07:43:49 +03:00
Oleg Kalachev	87cf44371b	Some fixes and updates to readme and other articles	2025-01-09 03:46:54 +03:00
Oleg Kalachev	5ee407af8d	Update ESP32-core to 3.1.0	2025-01-06 21:01:39 +03:00
Oleg Kalachev	59cb55cf94	Use ubuntu-20.04 runner to build simulator in CI The latest Ubuntu Gazebo 11 officially supports is Ubuntu 20.04	2025-01-06 00:56:25 +03:00
Oleg Kalachev	5db1258f78	Add battery connector cable to components list	2025-01-06 00:21:59 +03:00
Oleg Kalachev	732de2a5d6	Remove redundant inline specifiers In-class defined methods are specified as inline by default	2025-01-04 04:09:51 +03:00
Oleg Kalachev	e10475a5e0	Some minor cleanups and fixes	2024-12-28 23:57:44 +03:00
Oleg Kalachev	7ae5457bb4	Improve logging code Make it easer to add and remove log entries	2024-12-28 22:10:43 +03:00
Oleg Kalachev	299c8a6a02	Various minor fixes	2024-12-27 21:52:21 +03:00
Oleg Kalachev	43be27c43d	Fix joystick work in simulation Logic was broken as joystickGet never got called	2024-12-27 15:34:33 +03:00
Oleg Kalachev	2440c65c46	Remove unused include	2024-12-26 16:07:01 +03:00
Oleg Kalachev	8d7a4595f5	Rename flushParameters to more clear syncParameters	2024-12-26 01:14:26 +03:00
Oleg Kalachev	acc0274175	Minor fix	2024-12-25 02:21:17 +03:00
Oleg Kalachev	edd249566e	Increase motors output frequency	2024-12-25 02:13:57 +03:00
Oleg Kalachev	ca355e0162	Simplify motors duty cycle computation	2024-12-25 02:13:33 +03:00
Oleg Kalachev	2efae82177	Minor fixes	2024-12-25 01:41:45 +03:00
Oleg Kalachev	fd30027ea4	Support AUTOPILOT_VERSION message request to make qgc connection faster Don't have to wait until the request is timed out.	2024-12-23 17:59:35 +03:00
Oleg Kalachev	6f190295cf	Fix building article regarding new parameters subsystem	2024-12-23 13:59:44 +03:00
Oleg Kalachev	ae349fb73c	Implement parameters subsystem * Unified parameters storage. * Store parameters in flash on the hardware. * Store parameters in text file in simulation. * Work with parameters in command line. * Support parameters in MAVLink for working with parameters in QGC.	2024-12-23 13:00:02 +03:00
Oleg Kalachev	28f6cfff60	Fix SBUS simulation logic Don't consider zero values from not connected joystick	2024-12-23 04:04:00 +03:00
Oleg Kalachev	7533a9cbfa	Move ONE_G definition to flix.ino	2024-12-23 02:37:03 +03:00
Oleg Kalachev	3cc3014ca0	Improve logic of passing channels data in simulated SBUS Return the data the same way as on the real drone without touching channels global vairable	2024-12-23 02:04:22 +03:00
Oleg Kalachev	b6286a50b2	Minor change	2024-12-23 02:01:55 +03:00
Oleg Kalachev	4f2cf0c0b1	Don't let throttle be less than 0 in failsafe	2024-12-23 01:32:25 +03:00
Oleg Kalachev	f06a9301df	Add notice on removing props in motor test commands in help	2024-12-23 01:14:05 +03:00
Oleg Kalachev	41cde3261a	Minor troubleshooting article fix	2024-12-21 13:53:04 +03:00
Oleg Kalachev	f54da5bf42	Add CLI command for rebooting the drone	2024-12-20 20:59:59 +03:00
Oleg Kalachev	d01d5b7ecb	Improve Markdown linting * Move .markdownlint to the root so it applies to the main readme. * Improve .markdownlint, enable proper names checks. * Use markdownlint-cli2 instead of markdownlint-cli as it's more compatible with VSCode extension.	2024-12-17 17:16:19 +03:00
Oleg Kalachev	0608765347	Add link to textbook website to readme	2024-12-17 11:27:14 +03:00
Oleg Kalachev	b70d16c1f7	Update deploy-pages version to fix website deploy	2024-12-16 12:13:36 +03:00
Oleg Kalachev	f7253bed70	Temporarily disable macOS simulation build	2024-12-16 11:59:49 +03:00
Oleg Kalachev	9957205d8f	Fix website deploy	2024-12-16 11:58:35 +03:00
Oleg Kalachev	8440ddd3ee	Create book and deploy it to the website (#6 ) * Create book structure. * Add workflow for linting the markdown using markdownlint. * Add workflow for building the book with mdBook and deploying to the website. * Restyle mdBook and support GitHub-style alerts. * Add images zooming. * Add index, firmware structure and gyroscope articles.	2024-12-16 11:53:43 +03:00
Oleg Kalachev	66ba9518ae	Minor readme fix	2024-12-16 11:30:53 +03:00
Oleg Kalachev	d273b77ce2	Bring back macOS simulation build in Actions	2024-12-12 09:07:09 +03:00