Merge branch 'master' into run-sim

The Arduino docs probably has mistake offering non-existent ~/local/bin path instead of ~/.local/bin.
Some systems lack ~/.local/bin as well, so simply use /usr/local/bin.
Also install arduino-cli in CI the same way as in the docs to check them.

.editorconfig

@@ -0,0 +1,15 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[*.{ino,cpp,c,h,hpp,sdf,world}]
+charset = utf-8
+indent_style = tab
+tab_width = 4
+trim_trailing_whitespace = true
+
+[{*.yml,*.yaml,CMakeLists.txt}]
+indent_style = space
+indent_size = 2

.gitattributes

@@ -0,0 +1,2 @@
+# https://github.com/github-linguist/linguist/blob/master/docs/overrides.md
+*.h linguist-language=C++

.github/workflows/build.yml

@@ -0,0 +1,81 @@
+name: Build
+
+on:
+  push:
+    branches: [ '*' ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install Arduino CLI
+      run: curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=/usr/local/bin sh
+    - name: Build firmware
+      run: make
+
+  build_macos:
+    runs-on: macos-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install Arduino CLI
+      run: brew install arduino-cli
+    - name: Build firmware
+      run: make
+
+  build_windows:
+    runs-on: windows-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install Arduino CLI
+      run: choco install arduino-cli
+    - name: Install Make
+      run: choco install make
+    - name: Build firmware
+      run: make
+
+  build_simulator:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Install Arduino CLI
+      uses: arduino/setup-arduino-cli@v1.1.1
+    - uses: actions/checkout@v3
+    - name: Install Gazebo
+      run: curl -sSL http://get.gazebosim.org | sh
+    - name: Install SDL2
+      run: sudo apt-get install libsdl2-dev
+    - name: Build simulator
+      run: make build_simulator
+    - name: Run simulator
+      run: timeout --preserve-status 30 make simulator GAZEBO=gzserver || [ $? -eq 143 ]
+    - uses: actions/upload-artifact@v3
+      with:
+        name: gazebo-plugin-binary
+        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@v3
+    - 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
+    - name: Run simulator
+      run: |
+        brew install coreutils
+        timeout --preserve-status 30 make simulator GAZEBO=gzserver || [ $? -eq 143 ]

.gitignore

@@ -0,0 +1,5 @@
+*.hex
+*.elf
+build/
+tools/log/
+.dependencies

CNAME

@@ -1 +0,0 @@
-quadcopter.dev

Makefile

@@ -0,0 +1,44 @@
+BOARD = esp32:esp32:d1_mini32
+PORT := $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-*)
+PORT := $(strip $(PORT))
+
+build: .dependencies
+	arduino-cli compile --fqbn $(BOARD) flix
+
+upload: build
+	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" flix
+
+monitor:
+	arduino-cli monitor -p "$(PORT)" -c baudrate=115200
+
+dependencies .dependencies:
+	arduino-cli core update-index --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@2.0.11 --config-file arduino-cli.yaml
+	arduino-cli lib update-index
+	arduino-cli lib install "FlixPeriph"
+	arduino-cli lib install "MAVLink"@2.0.1
+	touch .dependencies
+
+gazebo/build cmake: gazebo/CMakeLists.txt
+	mkdir -p gazebo/build
+	cd gazebo/build && cmake ..
+
+build_simulator: .dependencies gazebo/build
+	make -C gazebo/build
+
+GAZEBO ?= gazebo
+simulator: build_simulator
+	GAZEBO_MODEL_PATH=$$GAZEBO_MODEL_PATH:${CURDIR}/gazebo/models \
+	GAZEBO_PLUGIN_PATH=$$GAZEBO_PLUGIN_PATH:${CURDIR}/gazebo/build \
+	$(GAZEBO) --verbose ${CURDIR}/gazebo/flix.world
+
+log:
+	PORT=$(PORT) tools/grab_log.py
+
+plot:
+	plotjuggler -d $(shell ls -t tools/log/*.csv | head -n1)
+
+clean:
+	rm -rf gazebo/build flix/build flix/cache .dependencies
+
+.PHONY: build upload monitor dependencies cmake build_simulator simulator log clean

README.md

@@ -0,0 +1,69 @@
+# flix
+
+**flix** (*flight + X*) — making an open source ESP32-based quadcopter from scratch.
+
+<img src="docs/img/flix.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.
+* Command line interface through USB port.
+* Wi-Fi support.
+* MAVLink support.
+* Control using mobile phone (with QGroundControl app).
+* ESCs with reverse mode support.
+* *Textbook and videos for students on writing a flight controller\*.*
+* *Completely 3D-printed frame*.*
+* *Position control and autonomous flights using external camera\**.
+* [Building and running instructions](docs/build.md).
+
+*\* — planned.*
+
+## It actually flies
+
+<a href="https://youtu.be/8GzzIQ3C6DQ"><img width=500 src="https://i3.ytimg.com/vi/8GzzIQ3C6DQ/maxresdefault.jpg"></a>
+
+See YouTube demo video: https://youtu.be/8GzzIQ3C6DQ.
+
+## Simulation
+
+Simulation in Gazebo using a plugin that runs original Arduino code is implemented:
+
+<img src="docs/img/simulator.png" width=500 alt="Flix simulator">
+
+## Schematics
+
+<img src="docs/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=/) of the drone.
+
+*\* — SBUS inverter is not needed as ESP32 supports [software pin inversion](https://github.com/bolderflight/sbus#inverted-serial).*
+
+## Components (version 0)
+
+|Component|Type|Image|Quantity|
+|-|-|-|-|
+|ESP32 Mini|Microcontroller board|<img src="docs/img/esp32.jpg" width=100>|1|
+|GY-91|IMU+LDO+barometer board|<img src="docs/img/gy-91.jpg" width=100>|1|
+|K100|Quadcopter frame|<img src="docs/img/frame.jpg" width=100>|1|
+|8520 3.7V brushed motor (**shaft 0.8mm!**)|Motor|<img src="docs/img/motor.jpeg" width=100>|4|
+|Hubsan 55 mm| Propeller|<img src="docs/img/prop.jpg" width=100>|4|
+|2.7A 1S Dual Way Micro Brush ESC|Motor ESC|<img src="docs/img/esc.jpg" width=100>|4|
+|KINGKONG TINY X8|RC transmitter|<img src="docs/img/tx.jpg" width=100>|1|
+|DF500 (SBUS)|RC receiver|<img src="docs/img/rx.jpg" width=100>|1|
+||~~SBUS inverter~~*|<img src="docs/img/inv.jpg" width=100>|~~1~~|
+|3.7 Li-Po 850 MaH 60C|Battery|||
+||Battery charger|<img src="docs/img/charger.jpg" width=100>|1|
+||Wires, connectors, tape, ...|||
+||3D-printed frame parts|||
+
+*\* — not needed as ESP32 supports [software pin inversion](https://github.com/bolderflight/sbus#inverted-serial).*
+
+## Materials
+
+Subscribe to Telegram-channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
+
+Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.

arduino-cli.yaml

@@ -0,0 +1,3 @@
+board_manager:
+  additional_urls:
+    - https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

docs/build.md

@@ -0,0 +1,130 @@
+# Building and running
+
+To build the firmware or the simulator, you need to clone the repository using git:
+
+```bash
+git clone https://github.com/okalachev/flix.git
+cd flix
+```
+
+## Simulation
+
+### Ubuntu
+
+1. Install Arduino CLI:
+
+   ```bash
+   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=/usr/local/bin sh
+   ```
+
+2. Install Gazebo 11:
+
+   ```bash
+   curl -sSL http://get.gazebosim.org | sh
+   ```
+
+   Set up your Gazebo environment variables:
+
+   ```bash
+   echo "source /usr/share/gazebo/setup.sh" >> ~/.bashrc
+   source ~/.bashrc
+   ```
+
+3. Install SDL2 and other dependencies:
+
+   ```bash
+   sudo apt-get update && sudo apt-get install build-essential libsdl2-dev
+   ```
+
+4. Add your user to the `input` group to enable joystick support (you need to re-login after this command):
+
+   ```bash
+   sudo usermod -a -G input $USER
+   ```
+
+5. Run the simulation:
+
+   ```bash
+   make simulator
+   ```
+
+### macOS
+
+1. Install Homebrew package manager, if you don't have it installed:
+
+   ```bash
+   /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
+   ```
+
+2. Install Arduino CLI, Gazebo 11 and SDL2:
+
+   ```bash
+   brew tap osrf/simulation
+   brew install arduino-cli
+   brew install gazebo11
+   brew install sdl2
+   ```
+
+   Set up your Gazebo environment variables:
+
+   ```bash
+   echo "source /opt/homebrew/share/gazebo/setup.sh" >> ~/.zshrc
+   source ~/.zshrc
+   ```
+
+3. Run the simulation:
+
+   ```bash
+   make simulator
+   ```
+
+### Flight
+
+Use USB remote control or QGroundControl mobile app (with *Virtual Joystick* setting enabled) to control the drone. *Auto-Center Throttle* setting **should be disabled**.
+
+## Firmware
+
+### Arduino IDE (Windows, Linux, macOS)
+
+1. Install [Arduino IDE](https://www.arduino.cc/en/software) (version 2 is recommended).
+2. Install ESP32 core using [Boards Manager](https://docs.arduino.cc/learn/starting-guide/cores).
+3. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
+   * `FlixPeriph`.
+   * `MAVLink`, version 2.0.1.
+4. Clone the project using git or [download the source code as a ZIP archive](https://codeload.github.com/okalachev/flix/zip/refs/heads/master).
+5. Open the downloaded Arduino sketch `flix/flix.ino` in Arduino IDE.
+6. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
+
+### Command line (Windows, Linux, macOS)
+
+1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
+2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
+3. Compile the firmware using `make`. Arduino dependencies will be installed automatically:
+
+   ```bash
+   make
+   ```
+
+   You can flash the firmware to the board using command:
+
+   ```bash
+   make upload
+   ```
+
+   You can also compile the firmware, upload it and start serial port monitoring using command:
+
+   ```bash
+   make upload monitor
+   ```
+
+See other available Make commands in the [Makefile](../Makefile).
+
+### Firmware code structure
+
+See [firmware overview](firmware.md) for more details.
+
+## Setup
+
+Before flight in simulation and on the real drone, you need to calibrate your remote control. Use drone's command line interface (`make monitor` on the real drone) and type `cr` command. Copy calibration results to the source code (`flix/rc.ino` and/or `gazebo/joystick.h`).
+
+On the real drone, you also need to calibrate the accelerometer and the gyroscope. Use `ca` and `cg` commands for that. Copy calibration results to the source code (`flix/imu.ino`).

docs/firmware.md

@@ -0,0 +1,37 @@
+# Firmware overview
+
+## Dataflow
+
+<img src="img/dataflow.svg" width=800 alt="Firmware dataflow diagram">
+
+The main loop is running at 1000 Hz. All the dataflow is happening through global variables (for simplicity):
+
+* `t` *(float)* — 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.
+* `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
+
+Firmware source files are located in `flix` directory. The key files are:
+
+* [`flix.ino`](../flix/flix.ino) — main entry point, Arduino sketch. Includes global variables definition and the main loop.
+* [`imu.ino`](../flix/imu.ino) — reading data from the IMU sensor (gyroscope and accelerometer), IMU calibration.
+* [`rc.ino`](../flix/rc.ino) — reading data from the RC receiver, RC calibration.
+* [`estimate.ino`](../flix/estimate.ino) — drone's attitude estimation, complementary filter.
+* [`control.ino`](../flix/control.ino) — drone's attitude and rates control, three-dimensional two-level cascade PID controller.
+* [`motors.ino`](../flix/motors.ino) — PWM motor outputs control.
+
+Utility files include:
+
+* [`vector.h`](../flix/vector.h), [`quaternion.h`](../flix/quaternion.h) — project's vector and quaternion libraries implementation.
+* [`pid.h`](../flix/pid.h) — generic PID controller implementation.
+* [`lpf.h`](../flix/lpf.h) — generic low-pass filter implementation.
+
+## Building
+
+See build instructions in [build.md](build.md).

docs/img/dataflow.svg

@@ -0,0 +1,330 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   width="613.59802mm"
+   height="267.24701mm"
+   viewBox="0 -10 613.59802 267.247"
+   version="1.1"
+   id="svg1"
+   xml:space="preserve"
+   inkscape:version="1.3.2 (091e20e, 2023-11-25)"
+   sodipodi:docname="dataflow.svg"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg"><sodipodi:namedview
+     id="namedview1"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:showpageshadow="2"
+     inkscape:pageopacity="0.0"
+     inkscape:pagecheckerboard="0"
+     inkscape:deskcolor="#d1d1d1"
+     inkscape:document-units="mm"
+     inkscape:zoom="0.34862039"
+     inkscape:cx="1219.091"
+     inkscape:cy="608.1113"
+     inkscape:window-width="1496"
+     inkscape:window-height="905"
+     inkscape:window-x="0"
+     inkscape:window-y="34"
+     inkscape:window-maximized="1"
+     inkscape:current-layer="svg1"><inkscape:page
+       x="0"
+       y="0"
+       width="613.59802"
+       height="267.24701"
+       id="page2"
+       margin="0"
+       bleed="0" /><inkscape:page
+       x="-30.32262"
+       y="-66.876167"
+       width="677.33331"
+       height="381"
+       id="page3"
+       margin="0"
+       bleed="0" /></sodipodi:namedview><defs
+     id="defs1"><color-profile
+       inkscape:label="sRGB IEC61966-2.1"
+       name="sRGB-IEC61966-2.1"
+       xlink:href="data:application/vnd.iccprofile;base64,AAAMbGxjbXMCEAAAbW50clJHQiBYWVogB84AAgAJAAYAMQAAYWNzcEFQUEwAAAAASUVDIHNSR0IAAAAAAAAAAAAAAAAAAPbWAAEAAAAA0y1sY21zAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARY3BydAAAAVAAAAAzZGVzYwAAAYQAAACQd3RwdAAAAhQAAAAUYmtwdAAAAigAAAAUclhZWgAAAjwAAAAUZ1hZWgAAAlAAAAAUYlhZWgAAAmQAAAAUZG1uZAAAAngAAABwZG1kZAAAAugAAACIdnVlZAAAA3AAAACGdmlldwAAA/gAAAAkbHVtaQAABBwAAAAUbWVhcwAABDAAAAAkdGVjaAAABFQAAAAMclRSQwAABGAAAAgMZ1RSQwAABGAAAAgMYlRSQwAABGAAAAgMdGV4dAAAAABDb3B5cmlnaHQgKGMpIDE5OTggSGV3bGV0dC1QYWNrYXJkIENvbXBhbnkAAGRlc2MAAAAAAAAAEnNSR0IgSUVDNjE5NjYtMi4xAAAAAAAAAAASAHMAUgBHAEIAIABJAEUAQwA2ADEAOQA2ADYALQAyAC4AMQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFhZWiAAAAAAAADzUQABAAAAARbMWFlaIAAAAAAAAAAAAAAAAAAAAABYWVogAAAAAAAAb6IAADj1AAADkFhZWiAAAAAAAABimQAAt4UAABjaWFlaIAAAAAAAACSgAAAPhAAAts9kZXNjAAAAAAAAABZJRUMgaHR0cDovL3d3dy5pZWMuY2gAAAAAAAAAAAAAABZJRUMgaHR0cDovL3d3dy5pZWMuY2gAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAZGVzYwAAAAAAAAAuSUVDIDYxOTY2LTIuMSBEZWZhdWx0IFJHQiBjb2xvdXIgc3BhY2UgLSBzUkdCAAAAAAAAAAAAAAAuSUVDIDYxOTY2LTIuMSBEZWZhdWx0IFJHQiBjb2xvdXIgc3BhY2UgLSBzUkdCAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGRlc2MAAAAAAAAALFJlZmVyZW5jZSBWaWV3aW5nIENvbmRpdGlvbiBpbiBJRUM2MTk2Ni0yLjEAAAAAAAAAAAAAACxSZWZlcmVuY2UgVmlld2luZyBDb25kaXRpb24gaW4gSUVDNjE5NjYtMi4xAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAB2aWV3AAAAAAATpP4AFF8uABDPFAAD7cwABBMLAANcngAAAAFYWVogAAAAAABMCVYAUAAAAFcf521lYXMAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAKPAAAAAnNpZyAAAAAAQ1JUIGN1cnYAAAAAAAAEAAAAAAUACgAPABQAGQAeACMAKAAtADIANwA7AEAARQBKAE8AVABZAF4AYwBoAG0AcgB3AHwAgQCGAIsAkACVAJoAnwCkAKkArgCyALcAvADBAMYAywDQANUA2wDgAOUA6wDwAPYA+wEBAQcBDQETARkBHwElASsBMgE4AT4BRQFMAVIBWQFgAWcBbgF1AXwBgwGLAZIBmgGhAakBsQG5AcEByQHRAdkB4QHpAfIB+gIDAgwCFAIdAiYCLwI4AkECSwJUAl0CZwJxAnoChAKOApgCogKsArYCwQLLAtUC4ALrAvUDAAMLAxYDIQMtAzgDQwNPA1oDZgNyA34DigOWA6IDrgO6A8cD0wPgA+wD+QQGBBMEIAQtBDsESARVBGMEcQR+BIwEmgSoBLYExATTBOEE8AT+BQ0FHAUrBToFSQVYBWcFdwWGBZYFpgW1BcUF1QXlBfYGBgYWBicGNwZIBlkGagZ7BowGnQavBsAG0QbjBvUHBwcZBysHPQdPB2EHdAeGB5kHrAe/B9IH5Qf4CAsIHwgyCEYIWghuCIIIlgiqCL4I0gjnCPsJEAklCToJTwlkCXkJjwmkCboJzwnlCfsKEQonCj0KVApqCoEKmAquCsUK3ArzCwsLIgs5C1ELaQuAC5gLsAvIC+EL+QwSDCoMQwxcDHUMjgynDMAM2QzzDQ0NJg1ADVoNdA2ODakNww3eDfgOEw4uDkkOZA5/DpsOtg7SDu4PCQ8lD0EPXg96D5YPsw/PD+wQCRAmEEMQYRB+EJsQuRDXEPURExExEU8RbRGMEaoRyRHoEgcSJhJFEmQShBKjEsMS4xMDEyMTQxNjE4MTpBPFE+UUBhQnFEkUahSLFK0UzhTwFRIVNBVWFXgVmxW9FeAWAxYmFkkWbBaPFrIW1hb6Fx0XQRdlF4kXrhfSF/cYGxhAGGUYihivGNUY+hkgGUUZaxmRGbcZ3RoEGioaURp3Gp4axRrsGxQbOxtjG4obshvaHAIcKhxSHHscoxzMHPUdHh1HHXAdmR3DHeweFh5AHmoelB6+HukfEx8+H2kflB+/H+ogFSBBIGwgmCDEIPAhHCFIIXUhoSHOIfsiJyJVIoIiryLdIwojOCNmI5QjwiPwJB8kTSR8JKsk2iUJJTglaCWXJccl9yYnJlcmhya3JugnGCdJJ3onqyfcKA0oPyhxKKIo1CkGKTgpaymdKdAqAio1KmgqmyrPKwIrNitpK50r0SwFLDksbiyiLNctDC1BLXYtqy3hLhYuTC6CLrcu7i8kL1ovkS/HL/4wNTBsMKQw2zESMUoxgjG6MfIyKjJjMpsy1DMNM0YzfzO4M/E0KzRlNJ402DUTNU01hzXCNf02NzZyNq426TckN2A3nDfXOBQ4UDiMOMg5BTlCOX85vDn5OjY6dDqyOu87LTtrO6o76DwnPGU8pDzjPSI9YT2hPeA+ID5gPqA+4D8hP2E/oj/iQCNAZECmQOdBKUFqQaxB7kIwQnJCtUL3QzpDfUPARANER0SKRM5FEkVVRZpF3kYiRmdGq0bwRzVHe0fASAVIS0iRSNdJHUljSalJ8Eo3Sn1KxEsMS1NLmkviTCpMcky6TQJNSk2TTdxOJU5uTrdPAE9JT5NP3VAnUHFQu1EGUVBRm1HmUjFSfFLHUxNTX1OqU/ZUQlSPVNtVKFV1VcJWD1ZcVqlW91dEV5JX4FgvWH1Yy1kaWWlZuFoHWlZaplr1W0VblVvlXDVchlzWXSddeF3JXhpebF69Xw9fYV+zYAVgV2CqYPxhT2GiYfViSWKcYvBjQ2OXY+tkQGSUZOllPWWSZedmPWaSZuhnPWeTZ+loP2iWaOxpQ2maafFqSGqfavdrT2una/9sV2yvbQhtYG25bhJua27Ebx5veG/RcCtwhnDgcTpxlXHwcktypnMBc11zuHQUdHB0zHUodYV14XY+dpt2+HdWd7N4EXhueMx5KnmJeed6RnqlewR7Y3vCfCF8gXzhfUF9oX4BfmJ+wn8jf4R/5YBHgKiBCoFrgc2CMIKSgvSDV4O6hB2EgITjhUeFq4YOhnKG14c7h5+IBIhpiM6JM4mZif6KZIrKizCLlov8jGOMyo0xjZiN/45mjs6PNo+ekAaQbpDWkT+RqJIRknqS45NNk7aUIJSKlPSVX5XJljSWn5cKl3WX4JhMmLiZJJmQmfyaaJrVm0Kbr5wcnImc951kndKeQJ6unx2fi5/6oGmg2KFHobaiJqKWowajdqPmpFakx6U4pammGqaLpv2nbqfgqFKoxKk3qamqHKqPqwKrdavprFys0K1ErbiuLa6hrxavi7AAsHWw6rFgsdayS7LCszizrrQltJy1E7WKtgG2ebbwt2i34LhZuNG5SrnCuju6tbsuu6e8IbybvRW9j74KvoS+/796v/XAcMDswWfB48JfwtvDWMPUxFHEzsVLxcjGRsbDx0HHv8g9yLzJOsm5yjjKt8s2y7bMNcy1zTXNtc42zrbPN8+40DnQutE80b7SP9LB00TTxtRJ1MvVTtXR1lXW2Ndc1+DYZNjo2WzZ8dp22vvbgNwF3IrdEN2W3hzeot8p36/gNuC94UThzOJT4tvjY+Pr5HPk/OWE5g3mlucf56noMui86Ubp0Opb6uXrcOv77IbtEe2c7ijutO9A78zwWPDl8XLx//KM8xnzp/Q09ML1UPXe9m32+/eK+Bn4qPk4+cf6V/rn+3f8B/yY/Sn9uv5L/tz/bf//"
+       id="color-profile1" /><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath2"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         id="path2" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath4"><path
+         d="m 745.9206,375.0079 h 404.1921 V 493.7148 H 745.9206 Z"
+         transform="matrix(1,0,0,-1,-874.5547,410.75391)"
+         id="path4" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath6"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         id="path6" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath7"><path
+         d="m 734.9959,651.142 h 426.0414 V 769.8489 H 734.9959 Z"
+         transform="matrix(1,0,0,-1,-786.22464,686.88802)"
+         id="path7" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath9"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         id="path9" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath10"><path
+         d="m 67.84839,771.7229 h 404.1921 V 890.4298 H 67.84839 Z"
+         transform="matrix(1,0,0,-1,-172.21011,807.46902)"
+         id="path10" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath12"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         id="path12" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath13"><path
+         d="m 1452.804,771.7229 h 375.3804 V 890.4298 H 1452.804 Z"
+         transform="matrix(1,0,0,-1,-1500.8361,807.46902)"
+         id="path13" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath15"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         id="path15" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath16"><path
+         d="m 1452.804,226.7937 h 375.3804 V 345.5006 H 1452.804 Z"
+         transform="matrix(1,0,0,-1,-1499.533,262.53983)"
+         id="path16" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath18"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(1,0,0,-1,-451.65591,778.64052)"
+         id="path18" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath20"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         id="path20" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath21"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(0.98150515,-0.1914358,-0.1914358,-0.98150515,-353.6359,868.10017)"
+         id="path21" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath23"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(0.89875521,0.43845065,0.43845065,-0.89875521,-1406.8193,-156.93149)"
+         id="path23" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath25"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(0.98480768,0.17364817,0.17364817,-0.98480768,-1293.1181,526.43111)"
+         id="path25" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath27"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(1,0,0,-1,-1132.0071,771.72292)"
+         id="path27" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath30"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(1,0,0,-1,-1142.931,782.32692)"
+         id="path30" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath33"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(1,0,0,-1,-1656.51,771.72572)"
+         id="path33" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath35"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(1,0,0,-1,-1703.37,542.87351)"
+         id="path35" /></clipPath><clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath37"><path
+         d="M 0,0 H 1920 V 1080 H 0 Z"
+         transform="matrix(1,0,0,-1,-270.40501,771.68402)"
+         id="path37" /></clipPath></defs><g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(-250.32262,-66.876165)" /><g
+     id="g1"
+     inkscape:groupmode="layer"
+     inkscape:label="1"
+     transform="matrix(0.26458333,0,0,0.26458334,-30.322612,-66.876165)"><g
+       id="g2"><path
+         id="path3"
+         d="m 786.6761,493.7148 h 322.6809 c 6.647,0 10.635,0 13.293,-1.11 3.833,-1.3949 6.852,-4.4141 8.247,-8.2468 1.11,-2.6586 1.11,-6.6466 1.11,-13.2932 v -73.4069 c 0,-6.6466 0,-10.6346 -1.11,-13.2932 -1.395,-3.8327 -4.414,-6.8518 -8.247,-8.2468 -2.658,-1.11 -6.646,-1.11 -13.293,-1.11 H 786.6761 c -6.6467,0 -10.6346,0 -13.2933,1.11 -3.8327,1.395 -6.8518,4.4141 -8.2468,8.2468 -1.1099,2.6586 -1.1099,6.6466 -1.1099,13.2932 v 73.4069 c 0,6.6466 0,10.6346 1.1099,13.2932 1.395,3.8327 4.4141,6.8519 8.2468,8.2468 2.6587,1.11 6.6466,1.11 13.2933,1.11 z"
+         style="fill:#0076ba;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)" /></g><g
+       id="g3"><text
+         id="text3"
+         xml:space="preserve"
+         transform="matrix(1.3333333,0,0,1.3333333,1166.0729,892.32813)"
+         clip-path="url(#clipPath4)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma;writing-mode:lr-tb;fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 21.33 49.02 67.169998 80.879997 114.33"
+           y="0"
+           sodipodi:role="line"
+           id="tspan3">rc.ino</tspan></text></g><g
+       id="g4"><path
+         id="path5"
+         d="m 775.7514,769.8489 h 344.5306 c 6.646,0 10.634,0 13.293,-1.11 3.833,-1.395 6.852,-4.4141 8.247,-8.2468 1.11,-2.6586 1.11,-6.6466 1.11,-13.2932 V 673.792 c 0,-6.6466 0,-10.6346 -1.11,-13.2932 -1.395,-3.8327 -4.414,-6.8519 -8.247,-8.2468 -2.659,-1.11 -6.647,-1.11 -13.293,-1.11 H 775.7514 c -6.6466,0 -10.6346,0 -13.2933,1.11 -3.8326,1.3949 -6.8518,4.4141 -8.2468,8.2468 -1.1099,2.6586 -1.1099,6.6466 -1.1099,13.2932 v 73.4069 c 0,6.6466 0,10.6346 1.1099,13.2932 1.395,3.8327 4.4142,6.8518 8.2468,8.2468 2.6587,1.11 6.6467,1.11 13.2933,1.11 z"
+         style="fill:#0076ba;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)"
+         clip-path="url(#clipPath6)" /></g><g
+       id="g6"><text
+         id="text6"
+         xml:space="preserve"
+         transform="matrix(1.3333333,0,0,1.3333333,1048.2995,524.14933)"
+         clip-path="url(#clipPath7)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma;writing-mode:lr-tb;fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 31.584 58.368 78.431999 92.136002 142.5 173.964 194.028 225.612 243.756 257.45999 290.90399"
+           y="0"
+           sodipodi:role="line"
+           id="tspan6">estimate.ino</tspan></text></g><g
+       id="g7"><path
+         id="path8"
+         d="M 108.6039,890.4298 H 431.285 c 6.6466,0 10.6346,0 13.2932,-1.1099 3.8327,-1.395 6.8519,-4.4142 8.2468,-8.2468 1.11,-2.6587 1.11,-6.6467 1.11,-13.2933 V 794.373 c 0,-6.6467 0,-10.6346 -1.11,-13.2933 -1.3949,-3.8327 -4.4141,-6.8518 -8.2468,-8.2468 -2.6586,-1.11 -6.6466,-1.11 -13.2932,-1.11 H 108.6039 c -6.6467,0 -10.63463,0 -13.29329,1.11 -3.83267,1.395 -6.85182,4.4141 -8.2468,8.2468 -1.10995,2.6587 -1.10995,6.6466 -1.10995,13.2933 v 73.4068 c 0,6.6466 0,10.6346 1.10995,13.2933 1.39498,3.8326 4.41413,6.8518 8.2468,8.2468 2.65866,1.1099 6.64659,1.1099 13.29329,1.1099 z"
+         style="fill:#0076ba;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)"
+         clip-path="url(#clipPath9)" /></g><g
+       id="g9"><text
+         id="text9"
+         xml:space="preserve"
+         transform="matrix(1.3333333,0,0,1.3333333,229.61347,363.37467)"
+         clip-path="url(#clipPath10)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma;writing-mode:lr-tb;fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 13.71 64.080002 97.529999 115.68 129.39 162.84"
+           y="0"
+           sodipodi:role="line"
+           id="tspan9">imu.ino</tspan></text></g><g
+       id="g10"><path
+         id="path11"
+         d="m 1493.56,890.4298 h 293.869 c 6.647,0 10.635,0 13.294,-1.1099 3.832,-1.395 6.851,-4.4142 8.246,-8.2468 1.11,-2.6587 1.11,-6.6467 1.11,-13.2933 V 794.373 c 0,-6.6467 0,-10.6346 -1.11,-13.2933 -1.395,-3.8327 -4.414,-6.8518 -8.246,-8.2468 -2.659,-1.11 -6.647,-1.11 -13.294,-1.11 H 1493.56 c -6.647,0 -10.635,0 -13.293,1.11 -3.833,1.395 -6.852,4.4141 -8.247,8.2468 -1.11,2.6587 -1.11,6.6466 -1.11,13.2933 v 73.4068 c 0,6.6466 0,10.6346 1.11,13.2933 1.395,3.8326 4.414,6.8518 8.247,8.2468 2.658,1.1099 6.646,1.1099 13.293,1.1099 z"
+         style="fill:#0076ba;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)"
+         clip-path="url(#clipPath12)" /></g><g
+       id="g12"><text
+         id="text12"
+         xml:space="preserve"
+         transform="matrix(1.3333333,0,0,1.3333333,2001.1147,363.37467)"
+         clip-path="url(#clipPath13)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma;writing-mode:lr-tb;fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 27.684 60.264 93.720001 113.79 135.12 167.7 181.41 199.57201 213.282 246.73801"
+           y="0"
+           sodipodi:role="line"
+           id="tspan12">control.ino</tspan></text></g><g
+       id="g13"><path
+         id="path14"
+         d="m 1493.56,345.5006 h 293.869 c 6.647,0 10.635,0 13.294,-1.1099 3.832,-1.395 6.851,-4.4142 8.246,-8.2468 1.11,-2.6587 1.11,-6.6467 1.11,-13.2933 v -73.4068 c 0,-6.6467 0,-10.6346 -1.11,-13.2933 -1.395,-3.8327 -4.414,-6.8518 -8.246,-8.2468 -2.659,-1.11 -6.647,-1.11 -13.294,-1.11 H 1493.56 c -6.647,0 -10.635,0 -13.293,1.11 -3.833,1.395 -6.852,4.4141 -8.247,8.2468 -1.11,2.6587 -1.11,6.6466 -1.11,13.2933 v 73.4068 c 0,6.6466 0,10.6346 1.11,13.2933 1.395,3.8326 4.414,6.8518 8.247,8.2468 2.658,1.1099 6.646,1.1099 13.293,1.1099 z"
+         style="fill:#0076ba;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)"
+         clip-path="url(#clipPath15)" /></g><g
+       id="g15"><text
+         id="text15"
+         xml:space="preserve"
+         transform="matrix(1.3333333,0,0,1.3333333,1999.3773,1089.9469)"
+         clip-path="url(#clipPath16)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma;writing-mode:lr-tb;fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 50.388 82.968002 103.038 135.618 157.242 184.02 202.18201 215.892 249.34801"
+           y="0"
+           sodipodi:role="line"
+           id="tspan15">motors.ino</tspan></text></g><g
+       id="g16"><path
+         id="path17"
+         d="m 0,0 c 89.24774,21.64997 181.7839,38.35706 277.6084,50.12129 l 2.9802,0.35217"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(1.3333333,0,0,1.3333333,602.20787,401.81267)"
+         clip-path="url(#clipPath18)" /><path
+         id="path19"
+         d="m 727.8571,716.602 25.2424,9.1006 -22.426,14.7336 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)"
+         clip-path="url(#clipPath20)" /></g><g
+       id="g20" /><g
+       id="g21"><text
+         id="text21"
+         xml:space="preserve"
+         transform="matrix(1.3086735,0.25524773,-0.25524773,1.3086735,684.37453,394.20507)"
+         clip-path="url(#clipPath21)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 22.108 42.028 56.248001 77.400002 89.508003 102.008 123.004 141.34399"
+           y="0"
+           sodipodi:role="line"
+           id="tspan21">gyro, acc</tspan></text></g><g
+       id="g22" /><g
+       id="g23"><text
+         id="text23"
+         xml:space="preserve"
+         transform="matrix(1.1983404,-0.58460093,0.58460093,1.1983404,1777.5907,805.62947)"
+         clip-path="url(#clipPath23)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 18.455999 40.175999 62.48 75.860001 90.080002 111.8 120.94 138.79201 154.104 175.94 197.776"
+           y="0"
+           sodipodi:role="line"
+           id="tspan23">controls[16]</tspan></text></g><g
+       id="g24" /><g
+       id="g25"><text
+         id="text25"
+         xml:space="preserve"
+         transform="matrix(1.3130771,-0.23153093,0.23153093,1.3130771,1576.0787,449.35853)"
+         clip-path="url(#clipPath25)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 13.732 34.743999 48.116001 69.167999 87.019997 99.112 111.604 132.616 145.668 159.03999 168.252 181.62399 203.916 226.008"
+           y="0"
+           sodipodi:role="line"
+           id="tspan25">rates, attitude</tspan></text></g><g
+       id="g26"><path
+         id="path26"
+         d="M 0,306.3767 C 237.7238,253.1408 395.5189,158.083 473.3852,21.20323 l 1.4097,-2.65533"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(1.3333333,0,0,1.3333333,1509.3427,411.03613)"
+         clip-path="url(#clipPath27)" /><path
+         id="path28"
+         d="m 1615.994,744.8981 0.656,26.8248 -21.853,-15.5703 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)" /></g><g
+       id="g28"><path
+         id="path29"
+         d="M 0,60.29815 C 99.1961,49.5746 200.9904,31.41576 305.383,5.821648 l 2.914,-0.728473"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(1.3333333,0,0,1.3333333,1523.908,396.89747)"
+         clip-path="url(#clipPath30)" /><path
+         id="path31"
+         d="m 1451.228,764.8644 20.373,17.4625 -26.194,5.821 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)" /></g><g
+       id="g31"><path
+         id="path32"
+         d="M 5.061111,0 C 39.5121,116.8397 39.6576,251.1261 5.497595,402.859 l -0.68786,2.9234"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(1.3333333,0,0,1.3333333,2208.68,411.0324)"
+         clip-path="url(#clipPath33)" /><path
+         id="path34"
+         d="m 1650.326,371.6119 6.184,-26.1104 17.178,20.6136 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)" /></g><g
+       id="g34" /><g
+       id="g35"><text
+         id="text35"
+         xml:space="preserve"
+         transform="matrix(1.3333333,0,0,1.3333333,2271.16,716.16867)"
+         clip-path="url(#clipPath35)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 33.591999 55.312 68.692001 90.412003 104.828"
+           y="0"
+           sodipodi:role="line"
+           id="tspan35">motors</tspan></text></g><g
+       id="g36"><path
+         id="path36"
+         d="M 1200.4,523.3549 C 431.1994,677.8194 31.45986,511.3581 1.181784,23.97107 L 1.034053,20.97453"
+         style="fill:none;stroke:#ff9300;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:12, 12;stroke-dashoffset:0;stroke-opacity:1"
+         transform="matrix(1.3333333,0,0,1.3333333,360.54,411.088)"
+         clip-path="url(#clipPath37)" /><path
+         id="path38"
+         d="m 283.5722,748.304 -13.1672,23.38 -10.8036,-24.5618 z"
+         style="fill:#ff9300;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,1440)" /></g></g></svg>

docs/img/schematics.svg

@@ -0,0 +1,847 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   version="1.1"
+   id="svg1"
+   width="1122.6667"
+   height="793.33331"
+   viewBox="0 0 1122.6667 793.33331"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <defs
+     id="defs1">
+    <color-profile
+       name="sRGB-IEC61966-2.1"
+       xlink:href="data:application/vnd.iccprofile;base64,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"
+       id="color-profile2" />
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath2">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         id="path2" />
+    </clipPath>
+    <color-profile
+       name="Display-P3"
+       xlink:href="data:application/vnd.iccprofile;base64,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"
+       id="color-profile3" />
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath5">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-752.49993,864.97407)"
+         id="path5" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath6">
+      <path
+         d="M 323.3782,236.4351 H 518.6217 V 379.3272 H 323.3782 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-877.1631,678.38361)"
+         id="path6" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath8">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-84.355831,865.05661)"
+         id="path8" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath10">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-84.355831,368.45549)"
+         id="path10" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath11">
+      <path
+         d="m 30.36917,94.69188 h 195.3121 v 66.89117 H 30.36917 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-134.25818,268.30492)"
+         id="path11" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath13">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-753,368.45549)"
+         id="path13" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath14">
+      <path
+         d="m 323.5975,94.69188 h 195.3121 v 66.89117 H 323.5975 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-838.74691,268.30492)"
+         id="path14" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath15">
+      <path
+         d="m 323.5975,94.69188 h 195.3121 v 66.89117 H 323.5975 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1049.6551,268.30492)"
+         id="path15" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath17">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-753,368.45549)"
+         id="path17" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath19">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-432.71735,654.78083)"
+         id="path19" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath21">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         id="path21" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath22">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-591.0243,591.01107)"
+         id="path22" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath24">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-976.18675,536.12963)"
+         id="path24" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath26">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-866.79009,439.55911)"
+         id="path26" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath28">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-502.51117,271.72444)"
+         id="path28" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath30">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-562.46578,294.8447)"
+         id="path30" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath32">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1170.4989,681.58102)"
+         id="path32" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath34">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1236.0252,695.13845)"
+         id="path34" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath36">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1603.7991,622.79116)"
+         id="path36" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath38">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1450.2767,481.38501)"
+         id="path38" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath40">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-152.63463,824.06234)"
+         id="path40" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath41">
+      <path
+         d="m 63.65076,327.618 h 128.7455 v 33.76771 H 63.65076 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-175.24065,773.92504)"
+         id="path41" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath42">
+      <path
+         d="m 63.65076,327.618 h 128.7455 v 33.76771 H 63.65076 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-243.6342,773.92504)"
+         id="path42" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath43">
+      <path
+         d="m 63.65076,327.618 h 128.7455 v 33.76771 H 63.65076 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-283.0092,773.92504)"
+         id="path43" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath44">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-212.88473,560.77723)"
+         id="path44" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath46">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-432.72783,779.78262)"
+         id="path46" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath48">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-588.82907,776.82395)"
+         id="path48" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath50">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-752.42811,1140.845)"
+         id="path50" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath51">
+      <path
+         d="m 323.3467,433.417 h 195.3121 v 66.89117 H 323.3467 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-865.05501,1040.6946)"
+         id="path51" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath53">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-307.72331,1036.0622)"
+         id="path53" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath55">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         id="path55" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath56">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-377.00861,973.65131)"
+         id="path56" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath58">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1170.5842,1056.8967)"
+         id="path58" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath60">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1396.2294,1013.572)"
+         id="path60" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath62">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1420.5002,368.45549)"
+         id="path62" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath63">
+      <path
+         d="m 616.3242,94.69188 h 195.3121 v 66.89117 H 616.3242 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1507.9562,268.30492)"
+         id="path63" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath64">
+      <path
+         d="m 616.3242,94.69188 h 195.3121 v 66.89117 H 616.3242 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1706.5597,268.30492)"
+         id="path64" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath66">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1420.5002,778.3221)"
+         id="path66" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath67">
+      <path
+         d="m 616.3242,274.4356 h 195.3121 v 66.89117 H 616.3242 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1546.3204,678.17176)"
+         id="path67" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath68">
+      <path
+         d="m 616.3242,274.4356 h 195.3121 v 66.89117 H 616.3242 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-1668.1954,678.17176)"
+         id="path68" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath70">
+      <path
+         d="m 0,60.6875 h 842 v 473.625 H 0 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-152.63463,715.88471)"
+         id="path70" />
+    </clipPath>
+    <clipPath
+       clipPathUnits="userSpaceOnUse"
+       id="clipPath71">
+      <path
+         d="m 63.66521,280.1776 h 128.7166 v 33.76771 H 63.66521 Z"
+         transform="matrix(2.2802848,0,0,-2.2802848,-197.83585,665.68264)"
+         id="path71" />
+    </clipPath>
+  </defs>
+  <g
+     id="g1">
+    <path
+       id="path1"
+       d="m 0,534.3125 h 842 v -474 H 0 Z"
+       style="fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+       transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)"
+       clip-path="url(#clipPath2)" />
+    <g
+       id="g2">
+      <path
+         id="path3"
+         d="m 342.5066,379.3272 h 156.9868 c 3.6693,0 5.8709,0 7.3386,-0.6128 2.1158,-0.7701 3.7825,-2.4368 4.5526,-4.5526 0.6128,-1.4677 0.6128,-3.6693 0.6128,-7.3386 V 248.9391 c 0,-3.6693 0,-5.8709 -0.6128,-7.3386 -0.7701,-2.1158 -2.4368,-3.7825 -4.5526,-4.5526 -1.4677,-0.6128 -3.6693,-0.6128 -7.3386,-0.6128 H 342.5066 c -3.6693,0 -5.8709,0 -7.3386,0.6128 -2.1158,0.7701 -3.7825,2.4368 -4.5526,4.5526 -0.6128,1.4677 -0.6128,3.6693 -0.6128,7.3386 v 117.8841 c 0,3.6693 0,5.8709 0.6128,7.3386 0.7701,2.1158 2.4368,3.7825 4.5526,4.5526 1.4677,0.6128 3.6693,0.6128 7.3386,0.6128 z"
+         style="fill:#0076ba;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+      <path
+         id="path4"
+         d="M 28.51265,0 H 386.4873 c 8.3671,0 13.3873,0 16.7341,1.397247 4.8247,1.756051 8.6253,5.556661 10.3814,10.381373 C 415,15.12543 415,20.14564 415,28.51265 V 297.322 c 0,8.367 0,13.3872 -1.3972,16.734 -1.7561,4.8247 -5.5567,8.6254 -10.3814,10.3814 -3.3468,1.3973 -8.367,1.3973 -16.7341,1.3973 H 28.51265 c -8.36701,0 -13.38722,0 -16.73403,-1.3973 C 6.953908,322.6814 3.153298,318.8807 1.397247,314.056 0,310.7092 0,305.689 0,297.322 V 28.51265 C 0,20.14564 0,15.12543 1.397247,11.77862 3.153298,6.953908 6.953908,3.153298 11.77862,1.397247 15.12543,0 20.14564,0 28.51265,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,440.00347,287.56373)"
+         clip-path="url(#clipPath5)" />
+    </g>
+    <g
+       id="g5">
+      <text
+         id="text5"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,512.8968,396.66733)"
+         clip-path="url(#clipPath6)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#ffffff;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 33.66 67.085999 100.164 132.918"
+           y="0"
+           id="tspan5">ESP32</tspan></text>
+    </g>
+    <g
+       id="g6">
+      <path
+         id="path7"
+         d="M 22.77821,0 H 392.3655 c 6.6843,0 10.6948,0 13.3685,1.116234 3.8544,1.402875 6.8906,4.43911 8.2935,8.293479 1.1162,2.673697 1.1162,6.684247 1.1162,13.368497 V 303.2218 c 0,6.6842 0,10.6948 -1.1162,13.3685 -1.4029,3.8544 -4.4391,6.8906 -8.2935,8.2935 C 403.0603,326 399.0498,326 392.3655,326 H 22.77821 c -6.68425,0 -10.6948,0 -13.368497,-1.1162 C 5.555344,323.4809 2.519109,320.4447 1.116234,316.5903 0,313.9166 0,309.906 0,303.2218 V 22.77821 C 0,16.09396 0,12.08341 1.116234,9.409713 2.519109,5.555344 5.555344,2.519109 9.409713,1.116234 12.08341,0 16.09396,0 22.77821,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,49.324733,287.51547)"
+         clip-path="url(#clipPath8)" />
+    </g>
+    <g
+       id="g8">
+      <path
+         id="path9"
+         d="M 25.43947,0 H 389.7043 c 7.4652,0 11.9443,0 14.9304,1.246647 4.3046,1.566779 7.6956,4.957749 9.2624,9.262433 1.2466,2.98608 1.2466,7.4652 1.2466,14.93039 V 127.0915 c 0,7.4652 0,11.9443 -1.2466,14.9304 -1.5668,4.3046 -4.9578,7.6956 -9.2624,9.2624 -2.9861,1.2466 -7.4652,1.2466 -14.9304,1.2466 H 25.43947 c -7.46519,0 -11.94431,0 -14.93039,-1.2466 C 6.204396,149.7175 2.813426,146.3265 1.246647,142.0219 0,139.0358 0,134.5567 0,127.0915 V 25.43947 C 0,17.97428 0,13.49516 1.246647,10.50908 2.813426,6.204396 6.204396,2.813426 10.50908,1.246647 13.49516,0 17.97428,0 25.43947,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,49.324733,577.8892)"
+         clip-path="url(#clipPath10)" />
+    </g>
+    <g
+       id="g10">
+      <text
+         id="text10"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,78.503747,636.44947)"
+         clip-path="url(#clipPath11)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 37.236 73.272003 92.028 128.18401 159.78 187.476 219.07201 232.78799 262.224 293.82001"
+           y="0"
+           id="tspan10">RC Receiver</tspan></text>
+    </g>
+    <g
+       id="g11">
+      <path
+         id="path12"
+         d="M 25.43947,0 H 389.7043 c 7.4652,0 11.9443,0 14.9304,1.246647 4.3046,1.566779 7.6956,4.957749 9.2624,9.262433 1.2466,2.98608 1.2466,7.4652 1.2466,14.93039 V 127.0915 c 0,7.4652 0,11.9443 -1.2466,14.9304 -1.5668,4.3046 -4.9578,7.6956 -9.2624,9.2624 -2.9861,1.2466 -7.4652,1.2466 -14.9304,1.2466 H 25.43947 c -7.46519,0 -11.94431,0 -14.93039,-1.2466 C 6.204396,149.7175 2.813426,146.3265 1.246647,142.0219 0,139.0358 0,134.5567 0,127.0915 V 25.43947 C 0,17.97428 0,13.49516 1.246647,10.50908 2.813426,6.204396 6.204396,2.813426 10.50908,1.246647 13.49516,0 17.97428,0 25.43947,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,440.29587,577.8892)"
+         clip-path="url(#clipPath13)" />
+    </g>
+    <g
+       id="g13">
+      <text
+         id="text13"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,490.434,636.44947)"
+         clip-path="url(#clipPath14)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 22.091999 55.043999 84.456001 116.028 137.64 157.692 189.26401"
+           y="0"
+           id="tspan13">Inverter</tspan></text>
+      <text
+         id="text14"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,613.75672,636.44947)"
+         clip-path="url(#clipPath15)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0"
+           y="0"
+           id="tspan14">*</tspan></text>
+    </g>
+    <path
+       id="path16"
+       d="M 85.74707,83.78818 H 296.6553"
+       style="fill:none;stroke:#000000;stroke-width:2.83382;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:10;stroke-dasharray:none;stroke-opacity:1"
+       transform="matrix(0.58472227,0,0,0.58472227,440.29587,577.8892)"
+       clip-path="url(#clipPath17)" />
+    <g
+       id="g17">
+      <path
+         id="path18"
+         d="M 0,3.82149 C 95.9403,15.70015 193.6043,15.48405 292.9919,3.173172 l 2.9749,-0.39679"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,253.01947,410.4684)"
+         clip-path="url(#clipPath19)" />
+      <path
+         id="path20"
+         d="m 318.95,280.5409 9.7369,6.6078 -11.1284,3.8248 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)"
+         clip-path="url(#clipPath21)" />
+    </g>
+    <g
+       id="g21" />
+    <g
+       id="g22">
+      <text
+         id="text22"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,345.58507,447.756)"
+         clip-path="url(#clipPath22)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 22.284 44.327999"
+           y="0"
+           id="tspan22">SPI</tspan></text>
+    </g>
+    <g
+       id="g23">
+      <path
+         id="path23"
+         d="M 0,164.6745 C 6.628704,118.7909 9.325715,71.89331 8.091034,23.98163 l -0.11774,-2.99781"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,570.79813,479.8464)"
+         clip-path="url(#clipPath24)" />
+      <path
+         id="path25"
+         d="m 436.9053,224.8049 -5.6715,10.3103 -4.8454,-10.7234 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+    </g>
+    <g
+       id="g25" />
+    <g
+       id="g26">
+      <text
+         id="text26"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,506.83147,536.31333)"
+         clip-path="url(#clipPath26)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 26.035999 50.032001 73.788002"
+           y="0"
+           id="tspan26">UART</tspan></text>
+    </g>
+    <g
+       id="g27">
+      <path
+         id="path27"
+         d="M 0,0.9516262 C 72.97435,4.664547 147.4808,4.757047 223.5194,1.229125 l 2.9962,-0.153649"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,293.82947,634.45)"
+         clip-path="url(#clipPath28)" />
+      <path
+         id="path29"
+         d="m 318.6642,113.3678 10.2417,5.7947 -10.7807,4.7165 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+    </g>
+    <g
+       id="g29" />
+    <g
+       id="g30">
+      <text
+         id="text30"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,328.88627,620.93107)"
+         clip-path="url(#clipPath30)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 22.284 45.848 72.092003"
+           y="0"
+           id="tspan30">SBUS</tspan></text>
+    </g>
+    <g
+       id="g31">
+      <path
+         id="path31"
+         d="M 0,0.946387 C 72.81716,4.651248 147.1611,4.745226 223.0318,1.22832 l 2.9962,-0.153549"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,684.4168,394.79773)"
+         clip-path="url(#clipPath32)" />
+      <path
+         id="path33"
+         d="m 611.3907,293.1074 10.2419,5.7943 -10.7805,4.7169 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+    </g>
+    <g
+       id="g33" />
+    <g
+       id="g34">
+      <text
+         id="text34"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,722.73147,386.8704)"
+         clip-path="url(#clipPath34)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 22.052 58.144001"
+           y="0"
+           id="tspan34">PWM</tspan></text>
+    </g>
+    <g
+       id="g35">
+      <path
+         id="path35"
+         d="M 8.544339,0 C -2.139819,73.24743 -2.804077,149.0941 6.551564,227.5399 l 0.391861,2.9755"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,937.77707,429.17347)"
+         clip-path="url(#clipPath36)" />
+      <path
+         id="path37"
+         d="m 700.9885,172.6465 6.5917,-9.7477 3.8432,11.122 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+    </g>
+    <g
+       id="g37" />
+    <g
+       id="g38">
+      <text
+         id="text38"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,848.00907,511.8568)"
+         clip-path="url(#clipPath38)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 22.032 43.751999 52.972 66.351997 87.348 109.456"
+           y="0"
+           id="tspan38">Voltage</tspan></text>
+    </g>
+    <g
+       id="g39">
+      <path
+         id="path39"
+         d="M 15.17917,0 H 263.407 c 4.4543,0 7.1269,0 8.9086,0.7438468 2.5685,0.9348622 4.5918,2.9581782 5.5267,5.5266902 0.7438,1.781727 0.7438,4.454313 0.7438,8.908633 v 46.64166 c 0,4.45432 0,7.12691 -0.7438,8.90863 -0.9349,2.56852 -2.9582,4.59183 -5.5267,5.52669 C 270.5339,77 267.8613,77 263.407,77 H 15.17917 C 10.72485,77 8.052264,77 6.270537,76.25615 3.702025,75.32129 1.678709,73.29798 0.7438468,70.72946 0,68.94774 0,66.27515 0,61.82083 V 15.17917 C 0,10.72485 0,8.052264 0.7438468,6.270537 1.678709,3.702025 3.702025,1.678709 6.270537,0.7438468 8.052264,0 10.72485,0 15.17917,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:3;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,89.248867,311.48573)"
+         clip-path="url(#clipPath40)" />
+    </g>
+    <g
+       id="g40">
+      <text
+         id="text40"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,102.46711,340.80213)"
+         clip-path="url(#clipPath41)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:30px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 16.377001 24.743999 41.120998 59.028"
+           y="0"
+           id="tspan40">3.7V </tspan></text>
+      <text
+         id="text41"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,142.45834,340.80213)"
+         clip-path="url(#clipPath42)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:30px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0"
+           y="0"
+           id="tspan41">→</tspan></text>
+      <text
+         id="text42"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,165.48178,340.80213)"
+         clip-path="url(#clipPath43)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:30px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 16.365 25.440001 41.805 59.700001 69.074997 84 104.355"
+           y="0"
+           id="tspan42">3.3V LDO</tspan></text>
+    </g>
+    <g
+       id="g43" />
+    <g
+       id="g44">
+      <text
+         id="text44"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,124.47844,465.4344)"
+         clip-path="url(#clipPath44)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 40.049999 70.800003 92.610001 125.34"
+           y="0"
+           id="tspan44">GY-91</tspan></text>
+    </g>
+    <g
+       id="g45">
+      <path
+         id="path45"
+         d="m 0,0 c 95.01414,6.248495 192.706,17.29379 293.0756,33.13588 l 2.9635,0.47787"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,253.0256,337.37707)"
+         clip-path="url(#clipPath46)" />
+      <path
+         id="path47"
+         d="m 317.4581,322.2402 11.2285,3.5199 -9.553,6.8709 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+    </g>
+    <g
+       id="g47" />
+    <g
+       id="g48">
+      <text
+         id="text48"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,344.30147,339.10707)"
+         clip-path="url(#clipPath48)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 21.836 33.952 55.787998"
+           y="0"
+           id="tspan48">3.3V</tspan></text>
+    </g>
+    <g
+       id="g49">
+      <path
+         id="path49"
+         d="M 25.43947,0 H 389.7043 c 7.4652,0 11.9443,0 14.9304,1.246647 4.3046,1.566779 7.6956,4.957749 9.2624,9.262433 1.2466,2.98608 1.2466,7.4652 1.2466,14.93039 V 127.0915 c 0,7.4652 0,11.9443 -1.2466,14.9304 -1.5668,4.3046 -4.9578,7.6956 -9.2624,9.2624 -2.9861,1.2466 -7.4652,1.2466 -14.9304,1.2466 H 25.43947 c -7.46519,0 -11.94431,0 -14.93039,-1.2466 C 6.204396,149.7175 2.813426,146.3265 1.246647,142.0219 0,139.0358 0,134.5567 0,127.0915 V 25.43947 C 0,17.97428 0,13.49516 1.246647,10.50908 2.813426,6.204396 6.204396,2.813426 10.50908,1.246647 13.49516,0 17.97428,0 25.43947,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,439.96147,126.25587)"
+         clip-path="url(#clipPath50)" />
+    </g>
+    <g
+       id="g50">
+      <text
+         id="text50"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,505.81693,184.816)"
+         clip-path="url(#clipPath51)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 35.652 67.164001 86.736 106.788 138.36 159.972"
+           y="0"
+           id="tspan50">Battery</tspan></text>
+    </g>
+    <g
+       id="g51">
+      <path
+         id="path52"
+         d="M 441.7047,0 C 216.8519,40.15725 73.8385,103.5263 12.66458,190.1072 l -1.58555,2.5531"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,179.93267,187.52467)"
+         clip-path="url(#clipPath53)" />
+      <path
+         id="path54"
+         d="m 136.0317,373.7609 -1.0822,-11.7174 10.0233,6.1647 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)"
+         clip-path="url(#clipPath55)" />
+    </g>
+    <g
+       id="g55" />
+    <g
+       id="g56">
+      <text
+         id="text56"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,220.44533,224.01773)"
+         clip-path="url(#clipPath56)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 29.1 50.919998 62.060001 83.879997"
+           y="0"
+           id="tspan56">&gt;3.7V</tspan></text>
+    </g>
+    <g
+       id="g57">
+      <path
+         id="path57"
+         d="m 0,0 c 227.9607,25.58255 371.5626,109.9501 430.8056,253.1027 l 1.0572,2.8138"
+         style="fill:none;stroke:#d5d5d5;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,684.46667,175.34227)"
+         clip-path="url(#clipPath58)" />
+      <path
+         id="path59"
+         d="m 697.3509,350.6439 8.6282,-8.0015 1.2243,11.7034 z"
+         style="fill:#d5d5d5;fill-opacity:1;fill-rule:nonzero;stroke:none"
+         transform="matrix(1.3333333,0,0,-1.3333333,0,793.33333)" />
+    </g>
+    <g
+       id="g59" />
+    <g
+       id="g60">
+      <text
+         id="text60"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,816.4064,200.6752)"
+         clip-path="url(#clipPath60)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 29.1 50.919998 62.060001 83.879997"
+           y="0"
+           id="tspan60">&gt;3.7V</tspan></text>
+    </g>
+    <g
+       id="g61">
+      <path
+         id="path61"
+         d="M 25.43947,0 H 389.7043 c 7.4652,0 11.9443,0 14.9304,1.246647 4.3046,1.566779 7.6956,4.957749 9.2624,9.262433 1.2466,2.98608 1.2466,7.4652 1.2466,14.93039 V 127.0915 c 0,7.4652 0,11.9443 -1.2466,14.9304 -1.5668,4.3046 -4.9578,7.6956 -9.2624,9.2624 -2.9861,1.2466 -7.4652,1.2466 -14.9304,1.2466 H 25.43947 c -7.46519,0 -11.94431,0 -14.93039,-1.2466 C 6.204396,149.7175 2.813426,146.3265 1.246647,142.0219 0,139.0358 0,134.5567 0,127.0915 V 25.43947 C 0,17.97428 0,13.49516 1.246647,10.50908 2.813426,6.204396 6.204396,2.813426 10.50908,1.246647 13.49516,0 17.97428,0 25.43947,0 Z"
+         style="fill:none;stroke:#ff9300;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,830.59813,577.8892)"
+         clip-path="url(#clipPath62)" />
+    </g>
+    <g
+       id="g62">
+      <text
+         id="text62"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,881.7356,636.44947)"
+         clip-path="url(#clipPath63)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 46.23 78.809998 98.879997 131.46001 153.084 179.862"
+           y="0"
+           id="tspan62">Motors </tspan></text>
+      <text
+         id="text63"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,997.86349,636.44947)"
+         clip-path="url(#clipPath64)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 19.804001"
+           y="0"
+           id="tspan63">x4</tspan></text>
+    </g>
+    <g
+       id="g64">
+      <path
+         id="path65"
+         d="M 25.43947,0 H 389.7043 c 7.4652,0 11.9443,0 14.9304,1.246647 4.3046,1.566779 7.6956,4.957749 9.2624,9.262433 1.2466,2.98608 1.2466,7.4652 1.2466,14.93039 V 127.0915 c 0,7.4652 0,11.9443 -1.2466,14.9304 -1.5668,4.3046 -4.9578,7.6956 -9.2624,9.2624 -2.9861,1.2466 -7.4652,1.2466 -14.9304,1.2466 H 25.43947 c -7.46519,0 -11.94431,0 -14.93039,-1.2466 C 6.204396,149.7175 2.813426,146.3265 1.246647,142.0219 0,139.0358 0,134.5567 0,127.0915 V 25.43947 C 0,17.97428 0,13.49516 1.246647,10.50908 2.813426,6.204396 6.204396,2.813426 10.50908,1.246647 13.49516,0 17.97428,0 25.43947,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:6;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,830.59813,338.23107)"
+         clip-path="url(#clipPath66)" />
+    </g>
+    <g
+       id="g66">
+      <text
+         id="text66"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,904.168,396.7912)"
+         clip-path="url(#clipPath67)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:60px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 33.66 67.085999 103.122"
+           y="0"
+           id="tspan66">ESC </tspan></text>
+      <text
+         id="text67"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,975.43103,396.7912)"
+         clip-path="url(#clipPath68)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:40px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 19.804001"
+           y="0"
+           id="tspan67">x4</tspan></text>
+    </g>
+    <g
+       id="g68">
+      <path
+         id="path69"
+         d="M 15.17917,0 H 263.407 c 4.4543,0 7.1269,0 8.9086,0.7438468 2.5685,0.9348622 4.5918,2.9581782 5.5267,5.5266902 0.7438,1.781727 0.7438,4.454313 0.7438,8.908633 v 46.64166 c 0,4.45432 0,7.12691 -0.7438,8.90863 -0.9349,2.56852 -2.9582,4.59183 -5.5267,5.52669 C 270.5339,77 267.8613,77 263.407,77 H 15.17917 C 10.72485,77 8.052264,77 6.270537,76.25615 3.702025,75.32129 1.678709,73.29798 0.7438468,70.72946 0,68.94774 0,66.27515 0,61.82083 V 15.17917 C 0,10.72485 0,8.052264 0.7438468,6.270537 1.678709,3.702025 3.702025,1.678709 6.270537,0.7438468 8.052264,0 10.72485,0 15.17917,0 Z"
+         style="fill:none;stroke:#0076ba;stroke-width:3;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+         transform="matrix(0.58472227,0,0,0.58472227,89.248867,374.7396)"
+         clip-path="url(#clipPath70)" />
+    </g>
+    <g
+       id="g70">
+      <text
+         id="text70"
+         xml:space="preserve"
+         transform="matrix(0.58472227,0,0,0.58472227,115.67903,404.09387)"
+         clip-path="url(#clipPath71)"><tspan
+           style="font-variant:normal;font-weight:normal;font-size:30px;font-family:Tahoma,Arial;writing-mode:lr-tb;fill:#000000;fill-opacity:1;fill-rule:nonzero;stroke:none"
+           x="0 23.115 39.653999 59.327999 75.705002 92.082001 108.459 124.836 134.211 145.401 168.51601"
+           y="0"
+           id="tspan70">MPU9250 IMU</tspan></text>
+    </g>
+  </g>
+</svg>

flix/cli.ino

@@ -0,0 +1,170 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Implementation of command line interface
+
+#include "pid.h"
+#include "vector.h"
+
+extern PID rollRatePID, pitchRatePID, yawRatePID, rollPID, pitchPID;
+extern LowPassFilter<Vector> ratesFilter;
+
+const char* motd =
+"\nWelcome to\n"
+" _______  __       __  ___   ___\n"
+"|   ____||  |     |  | \\  \\ /  /\n"
+"|  |__   |  |     |  |  \\  V  /\n"
+"|   __|  |  |     |  |   >   <\n"
+"|  |     |  `----.|  |  /  .  \\\n"
+"|__|     |_______||__| /__/ \\__\\\n\n"
+"Commands:\n\n"
+"help - show help\n"
+"show - show all parameters\n"
+"<name> <value> - set parameter\n"
+"ps - show pitch/roll/yaw\n"
+"psq - show attitude quaternion\n"
+"imu - show IMU data\n"
+"rc - show RC data\n"
+"mot - show motor data\n"
+"log - dump in-RAM log\n"
+"cr - calibrate RC\n"
+"cg - calibrate gyro\n"
+"ca - calibrate accel\n"
+"mfr, mfl, mrr, mrl - test appropriate motor\n"
+"fullmot <n> - full motor test\n"
+"reset - reset drone's state\n";
+
+const struct Param {
+	const char* name;
+	float* value;
+	float* value2;
+} params[] = {
+	{"rp", &rollRatePID.p, &pitchRatePID.p},
+	{"ri", &rollRatePID.i, &pitchRatePID.i},
+	{"rd", &rollRatePID.d, &pitchRatePID.d},
+
+	{"ap", &rollPID.p, &pitchPID.p},
+	{"ai", &rollPID.i, &pitchPID.i},
+	{"ad", &rollPID.d, &pitchPID.d},
+
+	{"yp", &yawRatePID.p, nullptr},
+	{"yi", &yawRatePID.i, nullptr},
+	{"yd", &yawRatePID.d, nullptr},
+
+	{"lpr", &ratesFilter.alpha, nullptr},
+	{"lpd", &rollRatePID.lpf.alpha, &pitchRatePID.lpf.alpha},
+
+	{"ss", &loopFreq, nullptr},
+	{"dt", &dt, nullptr},
+	{"t", &t, nullptr},
+};
+
+void doCommand(String& command, String& value) {
+	if (command == "help" || command == "motd") {
+		Serial.println(motd);
+	} else if (command == "show") {
+		showTable();
+	} else if (command == "ps") {
+		Vector a = attitude.toEulerZYX();
+		Serial.printf("roll: %f pitch: %f yaw: %f\n", a.x * RAD_TO_DEG, a.y * RAD_TO_DEG, a.z * RAD_TO_DEG);
+	} else if (command == "psq") {
+		Serial.printf("qx: %f qy: %f qz: %f qw: %f\n", attitude.x, attitude.y, attitude.z, attitude.w);
+	} else if (command == "imu") {
+		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);
+		printIMUCal();
+		Serial.printf("frequency: %f\n", loopFreq);
+	} else if (command == "rc") {
+		Serial.printf("Raw: throttle %d yaw %d pitch %d roll %d armed %d mode %d\n",
+			channels[RC_CHANNEL_THROTTLE], channels[RC_CHANNEL_YAW], channels[RC_CHANNEL_PITCH],
+			channels[RC_CHANNEL_ROLL], channels[RC_CHANNEL_ARMED], channels[RC_CHANNEL_MODE]);
+		Serial.printf("Control: throttle %f yaw %f pitch %f roll %f armed %f mode %f\n",
+			controls[RC_CHANNEL_THROTTLE], controls[RC_CHANNEL_YAW], controls[RC_CHANNEL_PITCH],
+			controls[RC_CHANNEL_ROLL], controls[RC_CHANNEL_ARMED], controls[RC_CHANNEL_MODE]);
+		Serial.printf("Mode: %s\n", getModeName());
+	} else if (command == "mot") {
+		Serial.printf("MOTOR front-right %f front-left %f rear-right %f rear-left %f\n",
+			motors[MOTOR_FRONT_RIGHT], motors[MOTOR_FRONT_LEFT], motors[MOTOR_REAR_RIGHT], motors[MOTOR_REAR_LEFT]);
+	} else if (command == "log") {
+		dumpLog();
+	} else if (command == "cr") {
+		calibrateRC();
+	} else if (command == "cg") {
+		calibrateGyro();
+	} else if (command == "ca") {
+		calibrateAccel();
+	} else if (command == "mfr") {
+		cliTestMotor(MOTOR_FRONT_RIGHT);
+	} else if (command == "mfl") {
+		cliTestMotor(MOTOR_FRONT_LEFT);
+	} else if (command == "mrr") {
+		cliTestMotor(MOTOR_REAR_RIGHT);
+	} else if (command == "mrl") {
+		cliTestMotor(MOTOR_REAR_LEFT);
+	} else if (command == "fullmot") {
+		fullMotorTest(value.toInt(), false);
+	} else if (command == "reset") {
+		attitude = Quaternion();
+	} else {
+		float val = value.toFloat();
+		// TODO: on error returns 0, check invalid value
+
+		for (uint8_t i = 0; i < sizeof(params) / sizeof(params[0]); i++) {
+			if (command == params[i].name) {
+				*params[i].value = val;
+				if (params[i].value2 != nullptr) *params[i].value2 = val;
+				Serial.print(command);
+				Serial.print(" = ");
+				Serial.println(val, 4);
+				return;
+			}
+		}
+		Serial.println("Invalid command: " + command);
+	}
+}
+
+void showTable() {
+	for (uint8_t i = 0; i < sizeof(params) / sizeof(params[0]); i++) {
+		Serial.print(params[i].name);
+		Serial.print(" ");
+		Serial.println(*params[i].value, 5);
+	}
+}
+
+void cliTestMotor(uint8_t n) {
+	Serial.printf("Testing motor %d\n", n);
+	motors[n] = 1;
+	sendMotors();
+	delay(5000);
+	motors[n] = 0;
+	sendMotors();
+	Serial.println("Done");
+}
+
+void parseInput() {
+	static bool showMotd = true;
+	static String command;
+	static String value;
+	static bool parsingCommand = true;
+
+	if (showMotd) {
+		Serial.println(motd);
+		showMotd = false;
+	}
+
+	while (Serial.available()) {
+		char c = Serial.read();
+		if (c == '\n') {
+			parsingCommand = true;
+			if (!command.isEmpty()) {
+				doCommand(command, value);
+			}
+			command.clear();
+			value.clear();
+		} else if (c == ' ') {
+			parsingCommand = false;
+		} else {
+			(parsingCommand ? command : value) += c;
+		}
+	}
+}

flix/control.ino

@@ -0,0 +1,175 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Flight control
+
+#include "vector.h"
+#include "quaternion.h"
+#include "pid.h"
+#include "lpf.h"
+
+#define PITCHRATE_P 0.05
+#define PITCHRATE_I 0.2
+#define PITCHRATE_D 0.001
+#define PITCHRATE_I_LIM 0.3
+#define ROLLRATE_P PITCHRATE_P
+#define ROLLRATE_I PITCHRATE_I
+#define ROLLRATE_D PITCHRATE_D
+#define ROLLRATE_I_LIM PITCHRATE_I_LIM
+#define YAWRATE_P 0.3
+#define YAWRATE_I 0.0
+#define YAWRATE_D 0.0
+#define YAWRATE_I_LIM 0.3
+#define ROLL_P 4.5
+#define ROLL_I 0
+#define ROLL_D 0
+#define PITCH_P ROLL_P
+#define PITCH_I ROLL_I
+#define PITCH_D ROLL_D
+#define YAW_P 3
+#define PITCHRATE_MAX radians(360)
+#define ROLLRATE_MAX radians(360)
+#define YAWRATE_MAX radians(360)
+#define MAX_TILT radians(30)
+
+#define RATES_D_LPF_ALPHA 0.2 // cutoff frequency ~ 40 Hz
+
+enum { MANUAL, ACRO, STAB, USER } mode = STAB;
+enum { YAW, YAW_RATE } yawMode = YAW;
+bool armed = false;
+
+PID rollRatePID(ROLLRATE_P, ROLLRATE_I, ROLLRATE_D, ROLLRATE_I_LIM, RATES_D_LPF_ALPHA);
+PID pitchRatePID(PITCHRATE_P, PITCHRATE_I, PITCHRATE_D, PITCHRATE_I_LIM, RATES_D_LPF_ALPHA);
+PID yawRatePID(YAWRATE_P, YAWRATE_I, YAWRATE_D);
+PID rollPID(ROLL_P, ROLL_I, ROLL_D);
+PID pitchPID(PITCH_P, PITCH_I, PITCH_D);
+PID yawPID(YAW_P, 0, 0);
+
+Quaternion attitudeTarget;
+Vector ratesTarget;
+Vector torqueTarget;
+float thrustTarget;
+
+void control() {
+	interpretRC();
+	if (mode == STAB) {
+		controlAttitude();
+		controlRate();
+		controlTorque();
+	} else if (mode == ACRO) {
+		controlRate();
+		controlTorque();
+	} else if (mode == MANUAL) {
+		controlTorque();
+	}
+}
+
+void interpretRC() {
+	armed = controls[RC_CHANNEL_THROTTLE] >= 0.05 && controls[RC_CHANNEL_ARMED] >= 0.5;
+
+	// NOTE: put ACRO or MANUAL modes there if you want to use them
+	if (controls[RC_CHANNEL_MODE] < 0.25) {
+		mode = STAB;
+	} else if (controls[RC_CHANNEL_MODE] < 0.75) {
+		mode = STAB;
+	} else {
+		mode = STAB;
+	}
+
+	thrustTarget = controls[RC_CHANNEL_THROTTLE];
+
+	if (mode == ACRO) {
+		yawMode = YAW_RATE;
+		ratesTarget.x = controls[RC_CHANNEL_ROLL] * ROLLRATE_MAX;
+		ratesTarget.y = -controls[RC_CHANNEL_PITCH] * PITCHRATE_MAX; // up pitch stick means tilt clockwise in frd
+		ratesTarget.z = controls[RC_CHANNEL_YAW] * YAWRATE_MAX;
+
+	} else if (mode == STAB) {
+		yawMode = controls[RC_CHANNEL_YAW] == 0 ? YAW : YAW_RATE;
+
+		attitudeTarget = Quaternion::fromEulerZYX(Vector(
+			controls[RC_CHANNEL_ROLL] * MAX_TILT,
+			-controls[RC_CHANNEL_PITCH] * MAX_TILT,
+			attitudeTarget.getYaw()));
+		ratesTarget.z = controls[RC_CHANNEL_YAW] * YAWRATE_MAX;
+
+	} else if (mode == MANUAL) {
+		// passthrough mode
+		yawMode = YAW_RATE;
+		torqueTarget = Vector(controls[RC_CHANNEL_ROLL], -controls[RC_CHANNEL_PITCH], controls[RC_CHANNEL_YAW]) * 0.01;
+	}
+
+	if (yawMode == YAW_RATE || !motorsActive()) {
+		// update yaw target as we don't have control over the yaw
+		attitudeTarget.setYaw(attitude.getYaw());
+	}
+}
+
+void controlAttitude() {
+	if (!armed) {
+		rollPID.reset();
+		pitchPID.reset();
+		yawPID.reset();
+		return;
+	}
+
+	const Vector up(0, 0, -1);
+	Vector upActual = attitude.rotate(up);
+	Vector upTarget = attitudeTarget.rotate(up);
+
+	Vector error = Vector::angularRatesBetweenVectors(upTarget, upActual);
+
+	ratesTarget.x = rollPID.update(error.x, dt);
+	ratesTarget.y = pitchPID.update(error.y, dt);
+
+	if (yawMode == YAW) {
+		ratesTarget.z = yawPID.update(wrapAngle(attitudeTarget.getYaw() - attitude.getYaw()), dt);
+	}
+}
+
+void controlRate() {
+	if (!armed) {
+		rollRatePID.reset();
+		pitchRatePID.reset();
+		yawRatePID.reset();
+		return;
+	}
+
+	Vector error = ratesTarget - rates;
+
+	// Calculate desired torque, where 0 - no torque, 1 - maximum possible torque
+	torqueTarget.x = rollRatePID.update(error.x, dt);
+	torqueTarget.y = pitchRatePID.update(error.y, dt);
+	torqueTarget.z = yawRatePID.update(error.z, dt);
+}
+
+void controlTorque() {
+	if (!armed) {
+		memset(motors, 0, sizeof(motors));
+		return;
+	}
+
+	motors[MOTOR_FRONT_LEFT] = thrustTarget + torqueTarget.x + torqueTarget.y - torqueTarget.z;
+	motors[MOTOR_FRONT_RIGHT] = thrustTarget - torqueTarget.x + torqueTarget.y + torqueTarget.z;
+	motors[MOTOR_REAR_LEFT] = thrustTarget + torqueTarget.x - torqueTarget.y + torqueTarget.z;
+	motors[MOTOR_REAR_RIGHT] = thrustTarget - torqueTarget.x - torqueTarget.y - torqueTarget.z;
+
+	motors[0] = constrain(motors[0], 0, 1);
+	motors[1] = constrain(motors[1], 0, 1);
+	motors[2] = constrain(motors[2], 0, 1);
+	motors[3] = constrain(motors[3], 0, 1);
+}
+
+bool motorsActive() {
+	return motors[0] > 0 || motors[1] > 0 || motors[2] > 0 || motors[3] > 0;
+}
+
+const char* getModeName() {
+	switch (mode) {
+		case MANUAL: return "MANUAL";
+		case ACRO: return "ACRO";
+		case STAB: return "STAB";
+		case USER: return "USER";
+		default: return "UNKNOWN";
+	}
+}

flix/estimate.ino

@@ -0,0 +1,50 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Attitude estimation from gyro and accelerometer
+
+#include "quaternion.h"
+#include "vector.h"
+#include "lpf.h"
+
+#define ONE_G 9.807f
+#define WEIGHT_ACC 0.5f
+#define RATES_LFP_ALPHA 0.2 // cutoff frequency ~ 40 Hz
+
+LowPassFilter<Vector> ratesFilter(RATES_LFP_ALPHA);
+
+void estimate() {
+	applyGyro();
+	applyAcc();
+	signalizeHorizontality();
+}
+
+void applyGyro() {
+	// filter gyro to get angular rates
+	rates = ratesFilter.update(gyro);
+
+	// apply rates to attitude
+	attitude *= Quaternion::fromAngularRates(rates * dt);
+	attitude.normalize();
+}
+
+void applyAcc() {
+	// test should we apply accelerometer gravity correction
+	float accNorm = acc.norm();
+	bool landed = !motorsActive() && abs(accNorm - ONE_G) < ONE_G * 0.1f;
+
+	if (!landed) return;
+
+	// calculate accelerometer correction
+	Vector up = attitude.rotate(Vector(0, 0, -1));
+	Vector correction = Vector::angularRatesBetweenVectors(acc, up) * dt * WEIGHT_ACC;
+
+	// apply correction
+	attitude *= Quaternion::fromAngularRates(correction);
+	attitude.normalize();
+}
+
+void signalizeHorizontality() {
+	float angle = Vector::angleBetweenVectors(attitude.rotate(Vector(0, 0, -1)), Vector(0, 0, -1));
+	setLED(angle < radians(15));
+}

flix/flix.ino

@@ -0,0 +1,66 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Main firmware file
+
+#include "vector.h"
+#include "quaternion.h"
+
+#define SERIAL_BAUDRATE 115200
+
+#define WIFI_ENABLED 0
+
+#define RC_CHANNELS 6
+#define RC_CHANNEL_ROLL 0
+#define RC_CHANNEL_PITCH 1
+#define RC_CHANNEL_THROTTLE 2
+#define RC_CHANNEL_YAW 3
+#define RC_CHANNEL_ARMED 4
+#define RC_CHANNEL_MODE 5
+
+#define MOTOR_REAR_LEFT 0
+#define MOTOR_REAR_RIGHT 1
+#define MOTOR_FRONT_RIGHT 2
+#define MOTOR_FRONT_LEFT 3
+
+float t = NAN; // current step time, s
+float dt; // time delta from previous step, s
+float loopFreq; // loop frequency, Hz
+int16_t channels[16]; // raw rc channels
+float controls[RC_CHANNELS]; // 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 [-1..1]
+
+void setup() {
+	Serial.begin(SERIAL_BAUDRATE);
+	Serial.println("Initializing flix");
+	disableBrownOut();
+	setupLED();
+	setupMotors();
+	setLED(true);
+#if WIFI_ENABLED == 1
+	setupWiFi();
+#endif
+	setupIMU();
+	setupRC();
+
+	setLED(false);
+	Serial.println("Initializing complete");
+}
+
+void loop() {
+	readIMU();
+	step();
+	readRC();
+	estimate();
+	control();
+	sendMotors();
+	parseInput();
+#if WIFI_ENABLED == 1
+	processMavlink();
+#endif
+	logData();
+}

flix/imu.ino

@@ -0,0 +1,121 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Work with the IMU sensor
+
+#include <SPI.h>
+#include <MPU9250.h>
+
+#define ONE_G 9.80665
+
+// NOTE: use 'ca' command to calibrate the accelerometer and put the values here
+Vector accBias(0, 0, 0);
+Vector accScale(1, 1, 1);
+
+MPU9250 IMU(SPI);
+Vector gyroBias;
+
+void setupIMU() {
+	Serial.println("Setup IMU");
+	bool status = IMU.begin();
+	if (!status) {
+		while (true) {
+			Serial.println("IMU begin error");
+			delay(1000);
+		}
+	}
+	calibrateGyro();
+}
+
+void configureIMU() {
+	IMU.setAccelRange(IMU.ACCEL_RANGE_4G);
+	IMU.setGyroRange(IMU.GYRO_RANGE_2000DPS);
+	IMU.setDlpfBandwidth(IMU.DLPF_BANDWIDTH_184HZ);
+	IMU.setSrd(0); // set sample rate to 1000 Hz
+}
+
+void readIMU() {
+	IMU.waitForData();
+	IMU.getGyro(gyro.x, gyro.y, gyro.z);
+	IMU.getAccel(acc.x, acc.y, acc.z);
+	// apply scale and bias
+	acc = (acc - accBias) / accScale;
+	gyro = gyro - gyroBias;
+}
+
+void calibrateGyro() {
+	const int samples = 1000;
+	Serial.println("Calibrating gyro, stand still");
+	IMU.setGyroRange(IMU.GYRO_RANGE_250DPS); // the most sensitive mode
+
+	gyroBias = Vector(0, 0, 0);
+	for (int i = 0; i < samples; i++) {
+		IMU.waitForData();
+		IMU.getGyro(gyro.x, gyro.y, gyro.z);
+		gyroBias = gyroBias + gyro;
+	}
+	gyroBias = gyroBias / samples;
+
+	printIMUCal();
+	configureIMU();
+}
+
+void calibrateAccel() {
+	Serial.println("Calibrating accelerometer");
+	IMU.setAccelRange(IMU.ACCEL_RANGE_2G); // the most sensitive mode
+	IMU.setDlpfBandwidth(IMU.DLPF_BANDWIDTH_20HZ);
+	IMU.setSrd(19);
+
+	Serial.setTimeout(60000);
+	Serial.print("Place level [enter] "); Serial.readStringUntil('\n');
+	calibrateAccelOnce();
+	Serial.print("Place nose up [enter] "); Serial.readStringUntil('\n');
+	calibrateAccelOnce();
+	Serial.print("Place nose down [enter] "); Serial.readStringUntil('\n');
+	calibrateAccelOnce();
+	Serial.print("Place on right side [enter] "); Serial.readStringUntil('\n');
+	calibrateAccelOnce();
+	Serial.print("Place on left side [enter] "); Serial.readStringUntil('\n');
+	calibrateAccelOnce();
+	Serial.print("Place upside down [enter] "); Serial.readStringUntil('\n');
+	calibrateAccelOnce();
+
+	printIMUCal();
+	configureIMU();
+}
+
+void calibrateAccelOnce() {
+	const int samples = 100;
+	static Vector accMax(-INFINITY, -INFINITY, -INFINITY);
+	static Vector accMin(INFINITY, INFINITY, INFINITY);
+
+	// Compute the average of the accelerometer readings
+	acc = Vector(0, 0, 0);
+	for (int i = 0; i < samples; i++) {
+		IMU.waitForData();
+		Vector sample;
+		IMU.getAccel(sample.x, sample.y, sample.z);
+		acc = acc + sample;
+	}
+	acc = acc / samples;
+
+	// Update the maximum and minimum values
+	if (acc.x > accMax.x) accMax.x = acc.x;
+	if (acc.y > accMax.y) accMax.y = acc.y;
+	if (acc.z > accMax.z) accMax.z = acc.z;
+	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;
+	Serial.printf("acc %f %f %f\n", acc.x, acc.y, acc.z);
+	Serial.printf("max %f %f %f\n", accMax.x, accMax.y, accMax.z);
+	Serial.printf("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 printIMUCal() {
+	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);
+}

flix/led.ino

@@ -0,0 +1,22 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Main LED control
+
+#define BLINK_PERIOD 500000
+
+#ifndef LED_BUILTIN
+#define LED_BUILTIN 2 // for ESP32 Dev Module
+#endif
+
+void setupLED() {
+	pinMode(LED_BUILTIN, OUTPUT);
+}
+
+void setLED(bool on) {
+	digitalWrite(LED_BUILTIN, on ? HIGH : LOW);
+}
+
+void blinkLED() {
+	setLED(micros() / BLINK_PERIOD % 2);
+}

flix/log.ino

@@ -0,0 +1,53 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// In-RAM logging
+
+#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;
+
+void logData() {
+	if (!armed) return;
+
+	static float 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.toEulerZYX().x;
+	logBuffer[logPointer][8] = attitude.toEulerZYX().y;
+	logBuffer[logPointer][9] = attitude.toEulerZYX().z;
+	logBuffer[logPointer][10] = attitudeTarget.toEulerZYX().x;
+	logBuffer[logPointer][11] = attitudeTarget.toEulerZYX().y;
+	logBuffer[logPointer][12] = attitudeTarget.toEulerZYX().z;
+	logBuffer[logPointer][13] = thrustTarget;
+
+	logPointer++;
+	if (logPointer >= LOG_SIZE) {
+		logPointer = 0;
+	}
+}
+
+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");
+	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]);
+		}
+		Serial.printf("%f\n", logBuffer[i][LOG_COLUMNS - 1]);
+	}
+}

flix/lpf.h

@@ -0,0 +1,38 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Low pass filter implementation
+
+#pragma once
+
+template <typename T> // Using template to make the filter usable for scalar and vector values
+class LowPassFilter {
+public:
+	float alpha; // smoothing constant, 1 means filter disabled
+	T output;
+
+	LowPassFilter(float alpha): alpha(alpha) {};
+
+	T update(const T input) {
+		if (alpha == 1) { // filter disabled
+			return input;
+		}
+
+		if (!initialized) {
+			output = input;
+			initialized = true;
+		}
+		return output = output * (1 - alpha) + input * alpha;
+	}
+
+	void setCutOffFrequency(float cutOffFreq, float dt) {
+		alpha = 1 - exp(-2 * PI * cutOffFreq * dt);
+	}
+
+	void reset() {
+		initialized = false;
+	}
+
+private:
+	bool initialized = false;
+};

flix/mavlink.ino

@@ -0,0 +1,100 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// MAVLink communication
+
+#if WIFI_ENABLED == 1
+
+#include <MAVLink.h>
+
+#define SYSTEM_ID 1
+#define PERIOD_SLOW 1.0
+#define PERIOD_FAST 0.1
+#define MAVLINK_CONTROL_SCALE 0.7f
+#define MAVLINK_CONTROL_YAW_DEAD_ZONE 0.1f
+
+void processMavlink() {
+	sendMavlink();
+	receiveMavlink();
+}
+
+void sendMavlink() {
+	static float lastSlow = 0;
+	static float lastFast = 0;
+
+	mavlink_message_t msg;
+	uint32_t time = t * 1000;
+
+	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 : 0),
+			0, MAV_STATE_STANDBY);
+		sendMessage(&msg);
+	}
+
+	if (t - lastFast >= PERIOD_FAST) {
+		lastFast = t;
+
+		const float zeroQuat[] = {0, 0, 0, 0};
+		mavlink_msg_attitude_quaternion_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
+			time, attitude.w, attitude.x, attitude.y, attitude.z, rates.x, rates.y, rates.z, zeroQuat);
+		sendMessage(&msg);
+
+		mavlink_msg_rc_channels_scaled_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time, 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];
+		memcpy(actuator, motors, sizeof(motors));
+		mavlink_msg_actuator_output_status_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time, 4, actuator);
+		sendMessage(&msg);
+
+		mavlink_msg_scaled_imu_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time,
+			acc.x * 1000, acc.y * 1000, acc.z * 1000,
+			gyro.x * 1000, gyro.y * 1000, gyro.z * 1000,
+			0, 0, 0, 0);
+		sendMessage(&msg);
+	}
+}
+
+void sendMessage(const void *msg) {
+	uint8_t buf[MAVLINK_MAX_PACKET_LEN];
+	int len = mavlink_msg_to_send_buffer(buf, (mavlink_message_t *)msg);
+	sendWiFi(buf, len);
+}
+
+void receiveMavlink() {
+	uint8_t buf[MAVLINK_MAX_PACKET_LEN];
+	int len = receiveWiFi(buf, MAVLINK_MAX_PACKET_LEN);
+
+	// New packet, parse it
+	mavlink_message_t msg;
+	mavlink_status_t status;
+	for (int i = 0; i < len; i++) {
+		if (mavlink_parse_char(MAVLINK_COMM_0, buf[i], &msg, &status)) {
+			handleMavlink(&msg);
+		}
+	}
+}
+
+void handleMavlink(const void *_msg) {
+	mavlink_message_t *msg = (mavlink_message_t *)_msg;
+	if (msg->msgid == MAVLINK_MSG_ID_MANUAL_CONTROL) {
+		mavlink_manual_control_t manualControl;
+		mavlink_msg_manual_control_decode(msg, &manualControl);
+		controls[RC_CHANNEL_THROTTLE] = manualControl.z / 1000.0f;
+		controls[RC_CHANNEL_PITCH] = manualControl.x / 1000.0f * MAVLINK_CONTROL_SCALE;
+		controls[RC_CHANNEL_ROLL] = manualControl.y / 1000.0f * MAVLINK_CONTROL_SCALE;
+		controls[RC_CHANNEL_YAW] = manualControl.r / 1000.0f * MAVLINK_CONTROL_SCALE;
+		controls[RC_CHANNEL_MODE] = 1; // STAB mode
+		controls[RC_CHANNEL_ARMED] = 1; // armed
+
+		if (abs(controls[RC_CHANNEL_YAW]) < MAVLINK_CONTROL_YAW_DEAD_ZONE) controls[RC_CHANNEL_YAW] = 0;
+	}
+}
+
+#endif

flix/motors.ino

@@ -0,0 +1,69 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Motors output control
+// Motor: 8520 3.7V
+// ESC: KINGDUO Micro Mini 4A 1S Brushed Esc 3.6-6V
+
+#define MOTOR_0_PIN 12
+#define MOTOR_1_PIN 13
+#define MOTOR_2_PIN 14
+#define MOTOR_3_PIN 15
+#define PWM_FREQUENCY 200
+#define PWM_RESOLUTION 8
+#define PWM_NEUTRAL 1500
+#define PWM_MIN 1600
+#define PWM_MAX 2300
+#define PWM_REVERSE_MIN 1400
+#define PWM_REVERSE_MAX 700
+
+void setupMotors() {
+	Serial.println("Setup Motors");
+
+	// configure PWM channels
+	ledcSetup(0, PWM_FREQUENCY, PWM_RESOLUTION);
+	ledcSetup(1, PWM_FREQUENCY, PWM_RESOLUTION);
+	ledcSetup(2, PWM_FREQUENCY, PWM_RESOLUTION);
+	ledcSetup(3, PWM_FREQUENCY, PWM_RESOLUTION);
+
+	// attach channels to motor pins
+	ledcAttachPin(MOTOR_0_PIN, 0);
+	ledcAttachPin(MOTOR_1_PIN, 1);
+	ledcAttachPin(MOTOR_2_PIN, 2);
+	ledcAttachPin(MOTOR_3_PIN, 3);
+
+	sendMotors();
+	Serial.println("Motors initialized");
+}
+
+uint16_t getPWM(float val, int n) {
+	if (val == 0) {
+		return PWM_NEUTRAL;
+	} else if (val > 0) {
+		return mapff(val, 0, 1, PWM_MIN, PWM_MAX);
+	} else {
+		return mapff(val, 0, -1, PWM_REVERSE_MIN, PWM_REVERSE_MAX);
+	}
+}
+
+uint8_t pwmToDutyCycle(uint16_t pwm) {
+	return map(pwm, 0, 1000000 / PWM_FREQUENCY, 0, (1 << PWM_RESOLUTION) - 1);
+}
+
+void sendMotors() {
+	ledcWrite(0, pwmToDutyCycle(getPWM(motors[0], 0)));
+	ledcWrite(1, pwmToDutyCycle(getPWM(motors[1], 1)));
+	ledcWrite(2, pwmToDutyCycle(getPWM(motors[2], 2)));
+	ledcWrite(3, pwmToDutyCycle(getPWM(motors[3], 3)));
+}
+
+void fullMotorTest(int n, bool reverse) {
+	printf("Full test for motor %d\n", n);
+	for (int pwm = PWM_NEUTRAL; pwm <= 2300 && pwm >= 700; pwm += reverse ? -100 : 100) {
+		printf("Motor %d: %d\n", n, pwm);
+		ledcWrite(n, pwmToDutyCycle(pwm));
+		delay(3000);
+	}
+	printf("Motor %d: %d\n", n, PWM_NEUTRAL);
+	ledcWrite(n, pwmToDutyCycle(PWM_NEUTRAL));
+}

flix/pid.h

@@ -0,0 +1,48 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// PID controller implementation
+
+#pragma once
+
+#include "lpf.h"
+
+class PID {
+public:
+	float p = 0;
+	float i = 0;
+	float d = 0;
+	float windup = 0;
+
+	float derivative = 0;
+	float integral = 0;
+
+	LowPassFilter<float> lpf; // low pass filter for derivative term
+
+	PID(float p, float i, float d, float windup = 0, float dAlpha = 1) : p(p), i(i), d(d), windup(windup), lpf(dAlpha) {};
+
+	float update(float error, float dt) {
+		integral += error * dt;
+
+		if (isfinite(prevError) && dt > 0) {
+			// calculate derivative if both dt and prevError are valid
+			derivative = (error - prevError) / dt;
+
+			// apply low pass filter to derivative
+			derivative = lpf.update(derivative);
+		}
+
+		prevError = error;
+
+		return p * error + constrain(i * integral, -windup, windup) + d * derivative; // PID
+	}
+
+	void reset() {
+		prevError = NAN;
+		integral = 0;
+		derivative = 0;
+	}
+
+private:
+	float prevError = NAN;
+};

flix/quaternion.h

@@ -0,0 +1,187 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Lightweight rotation quaternion library
+
+#pragma once
+
+#include "vector.h"
+
+class Quaternion : public Printable {
+public:
+	float w, x, y, z;
+
+	Quaternion(): w(1), x(0), y(0), z(0) {};
+
+	Quaternion(float w, float x, float y, float z): w(w), x(x), y(y), z(z) {};
+
+	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 / sqrt(a * a + b * b + c * c);
+		return Quaternion(cos2, a * sinNorm, b * sinNorm, c * sinNorm);
+	}
+
+	static Quaternion fromAngularRates(const Vector& rates) {
+		if (rates.zero()) {
+			return Quaternion();
+		}
+		return Quaternion::fromAxisAngle(rates.x, rates.y, rates.z, rates.norm());
+	}
+
+	static Quaternion fromEulerZYX(const Vector& euler) {
+		float cx = cos(euler.x / 2);
+		float cy = cos(euler.y / 2);
+		float cz = cos(euler.z / 2);
+		float sx = sin(euler.x / 2);
+		float sy = sin(euler.y / 2);
+		float sz = sin(euler.z / 2);
+
+		return Quaternion(
+			cx * cy * cz + sx * sy * sz,
+			sx * cy * cz - cx * sy * sz,
+			cx * sy * cz + sx * cy * sz,
+			cx * cy * sz - sx * sy * cz);
+	}
+
+	static Quaternion fromBetweenVectors(Vector u, Vector v) {
+		float dot = u.x * v.x + u.y * v.y + u.z * v.z;
+		float w1 = u.y * v.z - u.z * v.y;
+		float w2 = u.z * v.x - u.x * v.z;
+		float w3 = u.x * v.y - u.y * v.x;
+
+		Quaternion ret(
+			dot + sqrt(dot * dot + w1 * w1 + w2 * w2 + w3 * w3),
+			w1,
+			w2,
+			w3);
+		ret.normalize();
+		return ret;
+	}
+
+	void toAxisAngle(float& a, float& b, float& c, float& angle) {
+		angle = acos(w) * 2;
+		a = x / sin(angle / 2);
+		b = y / sin(angle / 2);
+		c = z / sin(angle / 2);
+	}
+
+	Vector toEulerZYX() const {
+		// https://github.com/ros/geometry2/blob/589caf083cae9d8fae7effdb910454b4681b9ec1/tf2/include/tf2/impl/utils.h#L87
+		Vector euler;
+		float sqx = x * x;
+		float sqy = y * y;
+		float sqz = z * z;
+		float sqw = w * w;
+		// Cases derived from https://orbitalstation.wordpress.com/tag/quaternion/
+		float sarg = -2 * (x * z - w * y) / (sqx + sqy + sqz + sqw); /* normalization added from urdfom_headers */
+		if (sarg <= -0.99999) {
+			euler.x = 0;
+			euler.y = -0.5 * PI;
+			euler.z = -2 * atan2(y, x);
+		} else if (sarg >= 0.99999) {
+			euler.x = 0;
+			euler.y = 0.5 * PI;
+			euler.z = 2 * atan2(y, x);
+		} else {
+			euler.x = atan2(2 * (y * z + w * x), sqw - sqx - sqy + sqz);
+			euler.y = asin(sarg);
+			euler.z = atan2(2 * (x * y + w * z), sqw + sqx - sqy - sqz);
+		}
+		return euler;
+	}
+
+	float getYaw() const {
+		// https://github.com/ros/geometry2/blob/589caf083cae9d8fae7effdb910454b4681b9ec1/tf2/include/tf2/impl/utils.h#L122
+		float yaw;
+		float sqx = x * x;
+		float sqy = y * y;
+		float sqz = z * z;
+		float sqw = w * w;
+		double sarg = -2 * (x * z - w * y) / (sqx + sqy + sqz + sqw);
+		if (sarg <= -0.99999) {
+			yaw = -2 * atan2(y, x);
+		} else if (sarg >= 0.99999) {
+			yaw = 2 * atan2(y, x);
+		} else {
+			yaw = atan2(2 * (x * y + w * z), sqw + sqx - sqy - sqz);
+		}
+		return yaw;
+	}
+
+	void setYaw(float yaw) {
+		// TODO: optimize?
+		Vector euler = toEulerZYX();
+		euler.z = yaw;
+		(*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) {
+		return Quaternion(
+			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);
+	}
+
+	Quaternion inversed() const {
+		float normSqInv = 1 / (w * w + x * x + y * y + z * z);
+		return Quaternion(
+			w * normSqInv,
+			-x * normSqInv,
+			-y * normSqInv,
+			-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) {
+		Quaternion qv(0, v.x, v.y, v.z);
+		Quaternion res = (*this) * qv * inversed();
+		return Vector(res.x, res.y, res.z);
+	}
+
+	Vector conjugateInversed(const Vector& v) {
+		Quaternion qv(0, v.x, v.y, v.z);
+		Quaternion res = inversed() * qv * (*this);
+		return Vector(res.x, res.y, res.z);
+	}
+
+	// Rotate vector by quaternion
+	inline Vector rotate(const Vector& v) {
+		return conjugateInversed(v);
+	}
+
+	inline bool finite() const {
+		return isfinite(w) && isfinite(x) && isfinite(y) && isfinite(z);
+	}
+
+	size_t printTo(Print& p) const {
+		size_t r = 0;
+		r += p.print(w, 15) + p.print(" ");
+		r += p.print(x, 15) + p.print(" ");
+		r += p.print(y, 15) + p.print(" ");
+		r += p.print(z, 15);
+		return r;
+	}
+};

flix/rc.ino

@@ -0,0 +1,54 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Work with the RC receiver
+
+#include <SBUS.h>
+
+// NOTE: use 'cr' command to calibrate the RC and put the values here
+int channelNeutral[] = {995, 883, 200, 972, 512, 512};
+int channelMax[] = {1651, 1540, 1713, 1630, 1472, 1472};
+
+SBUS RC(Serial2);
+
+void setupRC() {
+	Serial.println("Setup RC");
+	RC.begin();
+}
+
+void readRC() {
+	if (RC.read()) {
+		SBUSData data = RC.data();
+		memcpy(channels, data.ch, sizeof(channels)); // copy channels data
+		normalizeRC();
+	}
+}
+
+void normalizeRC() {
+	for (uint8_t i = 0; i < RC_CHANNELS; i++) {
+		controls[i] = mapf(channels[i], channelNeutral[i], channelMax[i], 0, 1);
+	}
+}
+
+void calibrateRC() {
+	Serial.println("Calibrate RC: move all sticks to maximum positions within 4 seconds");
+	Serial.println("··o     ··o\n···     ···\n···     ···");
+	delay(4000);
+	for (int i = 0; i < 30; i++) readRC(); // ensure the values are updated
+	for (int i = 0; i < RC_CHANNELS; i++) {
+		channelMax[i] = channels[i];
+	}
+	Serial.println("Calibrate RC: move all sticks to neutral positions within 4 seconds");
+	Serial.println("···     ···\n···     ·o·\n·o·     ···");
+	delay(4000);
+	for (int i = 0; i < 30; i++) readRC(); // ensure the values are updated
+	for (int i = 0; i < RC_CHANNELS; i++) {
+		channelNeutral[i] = channels[i];
+	}
+	printRCCal();
+}
+
+void printRCCal() {
+	printArray(channelNeutral, RC_CHANNELS);
+	printArray(channelMax, RC_CHANNELS);
+}

flix/time.ino

@@ -0,0 +1,27 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Time related functions
+
+void step() {
+	float now = micros() / 1000000.0;
+	dt = now - t;
+	t = now;
+
+	if (!(dt > 0)) {
+		dt = 0; // assume dt to be zero on first step and on reset
+	}
+
+	computeLoopFreq();
+}
+
+void computeLoopFreq() {
+	static float windowStart = 0;
+	static uint32_t freq = 0;
+	freq++;
+	if (t - windowStart >= 1) { // 1 second window
+		loopFreq = freq;
+		windowStart = t;
+		freq = 0;
+	}
+}

flix/util.ino

@@ -0,0 +1,50 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Utility functions
+
+#include <math.h>
+#include <soc/soc.h>
+#include <soc/rtc_cntl_reg.h>
+
+float mapf(long x, long in_min, long in_max, float out_min, float out_max) {
+	return (float)(x - in_min) * (out_max - out_min) / (float)(in_max - in_min) + out_min;
+}
+
+float mapff(float x, float in_min, float in_max, float out_min, float out_max) {
+	return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+}
+
+int8_t sign(float x) {
+	return (x > 0) - (x < 0);
+}
+
+float randomFloat(float min, float max) {
+	return min + (max - min) * (float)rand() / RAND_MAX;
+}
+
+// Wrap angle to [-PI, PI)
+float wrapAngle(float angle) {
+	angle = fmodf(angle, 2 * PI);
+	if (angle > PI) {
+		angle -= 2 * PI;
+	} else if (angle < -PI) {
+		angle += 2 * PI;
+	}
+	return angle;
+}
+
+template <typename T>
+void printArray(T arr[], int size) {
+	Serial.print("{");
+	for (uint8_t i = 0; i < size; i++) {
+		Serial.print(arr[i]);
+		if (i < size - 1) Serial.print(", ");
+	}
+	Serial.println("}");
+}
+
+// Disable reset on low voltage
+void disableBrownOut() {
+	WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0);
+}

flix/vector.h

@@ -0,0 +1,98 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Lightweight vector library
+
+#pragma once
+
+class Vector : public Printable {
+public:
+	float x, y, z;
+
+	Vector(): x(0), y(0), z(0) {};
+
+	Vector(float x, float y, float z): x(x), y(y), z(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;
+		y /= n;
+		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);
+	}
+
+	Vector operator + (const Vector& b) const {
+		return Vector(x + b.x, y + b.y, z + b.z);
+	}
+
+	Vector operator - (const Vector& b) const {
+		return Vector(x - b.x, y - b.y, z - b.z);
+	}
+
+	// Element-wise multiplication
+	Vector operator * (const Vector& b) const {
+		return Vector(x * b.x, y * b.y, z * b.z);
+	}
+
+	// Element-wise division
+	Vector operator / (const Vector& b) const {
+		return Vector(x / b.x, y / b.y, z / b.z);
+	}
+
+	inline bool operator == (const Vector& b) const {
+		return x == b.x && y == b.y && z == b.z;
+	}
+
+	inline bool operator != (const Vector& b) const {
+		return !(*this == b);
+	}
+
+	inline 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;
+	}
+
+	static Vector cross(const Vector& a, const Vector& b) {
+		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 angleBetweenVectors(const Vector& a, const Vector& b) {
+		return acos(constrain(dot(a, b) / (a.norm() * b.norm()), -1, 1));
+	}
+
+	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 = angleBetweenVectors(a, b);
+		return direction * angle;
+	}
+
+	size_t printTo(Print& p) const {
+		return
+			p.print(x, 15) + p.print(" ") +
+			p.print(y, 15) + p.print(" ") +
+			p.print(z, 15);
+	}
+};

flix/wifi.ino

@@ -0,0 +1,37 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Wi-Fi support
+
+#if WIFI_ENABLED == 1
+
+#include <WiFi.h>
+#include <WiFiAP.h>
+#include <WiFiUdp.h>
+
+#define WIFI_SSID "flix"
+#define WIFI_PASSWORD "flixwifi"
+#define WIFI_UDP_IP "255.255.255.255"
+#define WIFI_UDP_PORT 14550
+
+WiFiUDP udp;
+
+void setupWiFi() {
+	Serial.println("Setup Wi-Fi");
+	WiFi.softAP(WIFI_SSID, WIFI_PASSWORD);
+	IPAddress myIP = WiFi.softAPIP();
+	udp.begin(WIFI_UDP_PORT);
+}
+
+void sendWiFi(const uint8_t *buf, int len) {
+	udp.beginPacket(WIFI_UDP_IP, WIFI_UDP_PORT);
+	udp.write(buf, len);
+	udp.endPacket();
+}
+
+int receiveWiFi(uint8_t *buf, int len) {
+	udp.parsePacket();
+	return udp.read(buf, len);
+}
+
+#endif

gazebo/Arduino.h

@@ -0,0 +1,139 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Partial implementation of Arduino API for simulation
+
+#pragma once
+
+#include <cmath>
+#include <string>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/poll.h>
+
+#define PI 3.1415926535897932384626433832795
+#define DEG_TO_RAD 0.017453292519943295769236907684886
+#define RAD_TO_DEG 57.295779513082320876798154814105
+#define radians(deg) ((deg)*DEG_TO_RAD)
+#define degrees(rad) ((rad)*RAD_TO_DEG)
+
+#define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
+
+long map(long x, long in_min, long in_max, long out_min, long out_max) {
+	const long run = in_max - in_min;
+	const long rise = out_max - out_min;
+	const long delta = x - in_min;
+	return (delta * rise) / run + out_min;
+}
+
+class __FlashStringHelper;
+
+// Arduino String partial implementation
+// https://www.arduino.cc/reference/en/language/variables/data-types/stringobject/
+class String: public std::string {
+public:
+	long toInt() const { return atol(this->c_str()); }
+	float toFloat() const { return atof(this->c_str()); }
+	bool isEmpty() const { return this->empty(); }
+};
+
+class Print;
+
+class Printable {
+public:
+	virtual size_t printTo(Print& p) const = 0;
+};
+
+class Print {
+public:
+	size_t printf(const char *format, ...) {
+		va_list args;
+		va_start(args, format);
+		size_t result = vprintf(format, args);
+		va_end(args);
+		return result;
+	}
+
+	size_t print(int n) {
+		return printf("%d", n);
+	}
+
+	size_t print(float n, int digits = 2) {
+		return printf("%.*f", digits, n);
+	}
+
+	size_t println(float n, int digits = 2) {
+		return printf("%.*f\n", digits, n);
+	}
+
+	size_t print(const char* s) {
+		return printf("%s", s);
+	}
+
+	size_t println() {
+		return print("\n");
+	}
+
+	size_t println(const char* s) {
+		return printf("%s\n", s);
+	}
+
+	size_t println(const Printable& p) {
+		return p.printTo(*this) + print("\n");
+	}
+
+	size_t print(const String& s) {
+		return printf("%s", s.c_str());
+	}
+
+	size_t println(const std::string& s) {
+		return printf("%s\n", s.c_str());
+	}
+
+	size_t println(const String& s) {
+		return printf("%s\n", s.c_str());
+	}
+};
+
+class HardwareSerial: public Print {
+public:
+	void begin(unsigned long baud) {
+		// server is running in background by default, so doesn't have access to stdin
+		// https://github.com/gazebosim/gazebo-classic/blob/d45feeb51f773e63960616880b0544770b8d1ad7/gazebo/gazebo_main.cc#L216
+		// set foreground process group to current process group to allow reading from stdin
+		// https://stackoverflow.com/questions/58918188/why-is-stdin-not-propagated-to-child-process-of-different-process-group
+		signal(SIGTTOU, SIG_IGN);
+		tcsetpgrp(STDIN_FILENO, getpgrp());
+		signal(SIGTTOU, SIG_DFL);
+	};
+
+	int available() {
+		// to implement for Windows, see https://stackoverflow.com/a/71992965/6850197
+		struct pollfd pfd = { .fd = STDIN_FILENO, .events = POLLIN };
+		return poll(&pfd, 1, 0) > 0;
+	}
+
+	int read() {
+		if (available()) {
+			char c;
+			::read(STDIN_FILENO, &c, 1); // use raw read to avoid C++ buffering
+			// https://stackoverflow.com/questions/45238997/does-getchar-function-has-its-own-buffer-to-store-remaining-input
+			return c;
+		}
+		return -1;
+	}
+
+	void setRxInvert(bool invert) {};
+};
+
+HardwareSerial Serial, Serial2;
+
+void delay(uint32_t ms) {
+	std::this_thread::sleep_for(std::chrono::milliseconds(ms));
+}
+
+unsigned long __micros;
+
+unsigned long micros() {
+	return __micros;
+}

gazebo/CMakeLists.txt

@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
+project(flix_gazebo)
+
+# === gazebo plugin
+find_package(gazebo REQUIRED)
+find_package(SDL2 REQUIRED)
+include_directories(${GAZEBO_INCLUDE_DIRS})
+link_directories(${GAZEBO_LIBRARY_DIRS})
+list(APPEND CMAKE_CXX_FLAGS "${GAZEBO_CXX_FLAGS}")
+
+set(FLIX_SOURCE_DIR ../flix)
+include_directories(${FLIX_SOURCE_DIR})
+
+set(CMAKE_BUILD_TYPE RelWithDebInfo)
+add_library(flix SHARED simulator.cpp)
+target_link_libraries(flix ${GAZEBO_LIBRARIES} ${SDL2_LIBRARIES})
+target_include_directories(flix PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+
+# Include dir for MAVLink-Arduino library
+target_include_directories(flix PUBLIC $ENV{HOME}/Arduino/libraries/MAVLink)
+target_include_directories(flix PUBLIC $ENV{HOME}/Documents/Arduino/libraries/MAVLink)

gazebo/README.md

@@ -0,0 +1,15 @@
+# Gazebo Simulation
+
+<img src="../docs/img/simulator.png" width=500 alt="Flix simulator">
+
+## Building and running
+
+See [building and running instructions](../docs/build.md#simulation).
+
+## Code structure
+
+Flix simulator is based on [Gazebo Classic](https://classic.gazebosim.org) and consists of the following components:
+
+* Physical model of the drone: [`models/flix/flix.sdf`](models/flix/flix.sdf).
+* Plugin for Gazebo: [`simulator.cpp`](simulator.cpp). The plugin is attached to the physical model. It receives stick positions from the controller, gets the data from the virtual sensors, and then passes this data to the Arduino code.
+* Arduino imitation: [`Arduino.h`](Arduino.h). This file contains partial implementation of the Arduino API, that is working within Gazebo plugin environment.

gazebo/SBUS.h

@@ -0,0 +1,24 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// SBUS library mock to make it possible to compile simulator with rc.ino
+
+#include "joystick.h"
+
+struct SBUSData {
+	int16_t ch[16];
+};
+
+class SBUS {
+public:
+	SBUS(HardwareSerial& bus, const bool inv = true) {};
+	void begin() {};
+	bool read() { return joystickGet(); };
+	SBUSData data() {
+		SBUSData data;
+		for (uint8_t i = 0; i < 16; i++) {
+			data.ch[i] = channels[i];
+		}
+		return data;
+	};
+};

gazebo/flix.h

@@ -0,0 +1,59 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Declarations of some functions and variables in Arduino code
+
+#include <cmath>
+#include <stdio.h>
+#include "vector.h"
+#include "quaternion.h"
+#include "Arduino.h"
+#include "wifi.h"
+
+#define RC_CHANNELS 6
+
+#define MOTOR_REAR_LEFT 0
+#define MOTOR_FRONT_LEFT 3
+#define MOTOR_FRONT_RIGHT 2
+#define MOTOR_REAR_RIGHT 1
+
+#define WIFI_ENABLED 1
+
+float t = NAN;
+float dt;
+float loopFreq;
+float motors[4];
+int16_t channels[16]; // raw rc channels
+float controls[RC_CHANNELS];
+Vector acc;
+Vector gyro;
+Vector rates;
+Quaternion attitude;
+
+// declarations
+void computeLoopFreq();
+void applyGyro();
+void applyAcc();
+void signalizeHorizontality();
+void control();
+void interpretRC();
+void controlAttitude();
+void controlRate();
+void controlTorque();
+void showTable();
+bool motorsActive();
+void cliTestMotor(uint8_t n);
+void printRCCal();
+void processMavlink();
+void sendMavlink();
+void sendMessage(const void *msg);
+void receiveMavlink();
+void handleMavlink(const void *_msg);
+
+// mocks
+void setLED(bool on) {};
+void calibrateGyro() { printf("Skip gyro calibrating\n"); };
+void calibrateAccel() { printf("Skip accel calibrating\n"); };
+void fullMotorTest(int n, bool reverse) { printf("Skip full motor test\n"); };
+void sendMotors() {};
+void printIMUCal() { printf("cal: N/A\n"); };

gazebo/flix.world

@@ -0,0 +1,29 @@
+<?xml version="1.0"?>
+<sdf version="1.4">
+	<world name="default">
+		<scene>
+			<ambient>1 1 1 1</ambient>
+			<sky/>
+			<origin_visual>false</origin_visual>
+			<grid>false</grid>
+		</scene>
+		<gui>
+			<camera name="user_camera">
+				<pose>-2 -0.3 1.5 0 0.5 0.1</pose>
+			</camera>
+		</gui>
+		<physics type="ode">
+			<max_step_size>0.001</max_step_size>
+		</physics>
+		<include>
+			<uri>model://floor</uri>
+		</include>
+		<include>
+			<uri>model://sun</uri>
+		</include>
+		<include>
+			<uri>model://flix</uri>
+			<pose>0 0 0.2 0 0 0</pose>
+		</include>
+	</world>
+</sdf>

gazebo/joystick.h

@@ -0,0 +1,56 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Joystick support for simulation
+
+#include <SDL2/SDL.h>
+#include <gazebo/gazebo.hh>
+#include <iostream>
+
+// simulation calibration overrides, NOTE: use `cr` command and replace with the actual values
+const int channelNeutralOverride[] = {-258, -258, -27349, 0, -27349, 0};
+const int channelMaxOverride[] = {27090, 27090, 27090, 27090, -5676, 1};
+
+#define RC_CHANNEL_ROLL 0
+#define RC_CHANNEL_PITCH 1
+#define RC_CHANNEL_THROTTLE 2
+#define RC_CHANNEL_YAW 3
+#define RC_CHANNEL_ARMED 5
+#define RC_CHANNEL_MODE 4
+
+SDL_Joystick *joystick;
+bool joystickInitialized = false, warnShown = false;
+
+void normalizeRC();
+
+void joystickInit() {
+	SDL_Init(SDL_INIT_JOYSTICK);
+	joystick = SDL_JoystickOpen(0);
+	if (joystick != NULL) {
+		joystickInitialized = true;
+		gzmsg << "Joystick initialized: " << SDL_JoystickNameForIndex(0) << std::endl;
+	} else if (!warnShown) {
+		gzwarn << "Joystick not found, begin waiting for joystick..." << std::endl;
+		warnShown = true;
+	}
+
+	// apply calibration overrides
+	extern int channelNeutral[RC_CHANNELS];
+	extern int channelMax[RC_CHANNELS];
+	memcpy(channelNeutral, channelNeutralOverride, sizeof(channelNeutralOverride));
+	memcpy(channelMax, channelMaxOverride, sizeof(channelMaxOverride));
+}
+
+bool joystickGet() {
+	if (!joystickInitialized) {
+		joystickInit();
+		return false;
+	}
+
+	SDL_JoystickUpdate();
+
+	for (uint8_t i = 0; i < 8; i++) {
+		channels[i] = SDL_JoystickGetAxis(joystick, i);
+	}
+	return true;
+}

gazebo/models/flix/flix.sdf

@@ -0,0 +1,69 @@
+<?xml version="1.0"?>
+<sdf version="1.5">
+	<model name="flix">
+		<link name="body">
+			<inertial>
+				<mass>0.065</mass>
+				<inertia>
+					<ixx>3.55E-5</ixx>
+					<iyy>4.23E-5</iyy>
+					<izz>7.47E-5</izz>
+				</inertia>
+			</inertial>
+			<collision name="collision">
+				<geometry>
+					<box>
+						<size>0.125711 0.125711 0.022</size>
+					</box>
+				</geometry>
+			</collision>
+			<visual name="body">
+				<geometry>
+					<mesh><uri>model://flix/flix.dae</uri></mesh>
+				</geometry>
+			</visual>
+			<sensor name="imu" type="imu">
+				<always_on>1</always_on>
+				<visualize>1</visualize>
+				<update_rate>1000</update_rate>
+				<imu>
+					<angular_velocity>
+						<x>
+							<noise type="gaussian">
+								<stddev>0.00174533</stddev><!-- 0.1 degrees per second -->
+							</noise>
+						</x>
+						<y>
+							<noise type="gaussian">
+								<stddev>0.00174533</stddev>
+							</noise>
+						</y>
+						<z>
+							<noise type="gaussian">
+								<stddev>0.00174533</stddev>
+							</noise>
+						</z>
+					</angular_velocity>
+					<linear_acceleration>
+						<x>
+							<noise type="gaussian">
+								<stddev>0.0784</stddev><!-- 8 mg -->
+							</noise>
+						</x>
+						<y>
+							<noise type="gaussian">
+								<stddev>0.0784</stddev>
+							</noise>
+						</y>
+						<z>
+							<noise type="gaussian">
+								<stddev>0.0784</stddev>
+							</noise>
+						</z>
+					</linear_acceleration>
+				</imu>
+			</sensor>
+		</link>
+		<plugin name="flix" filename="libflix.so"/>
+	</model>
+</sdf>

gazebo/models/flix/model.config

@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+<model>
+    <name>flix</name>
+    <version>1.0</version>
+    <sdf version="1.5">flix.sdf</sdf>
+    <author>
+        <name>Oleg Kalachev</name>
+        <email>okalachev@gmail.com</email>
+    </author>
+    <license>Unknown</license>
+    <description>
+        Flix quadrotor
+    </description>
+</model>

gazebo/models/floor/floor.sdf

@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+<sdf version="1.5">
+	<model name="floor">
+		<static>true</static>
+		<link name="link">
+			<pose>0 0 -0.02 0 0 0</pose>
+			<collision name="collision">
+				<geometry>
+					<box>
+						<size>200 200 .02</size>
+					</box>
+				</geometry>
+			</collision>
+			<visual name="visual">
+				<cast_shadows>false</cast_shadows>
+				<geometry>
+					<box>
+						<size>200 200 .02</size>
+					</box>
+				</geometry>
+				<material>
+					<script>
+						<uri>model://floor/materials/scripts</uri>
+						<uri>model://floor/materials/textures</uri>
+						<name>parquet</name>
+					</script>
+				</material>
+			</visual>
+		</link>
+	</model>
+</sdf>

gazebo/models/floor/materials/scripts/floor.material

@@ -0,0 +1,20 @@
+material parquet
+{
+	technique
+	{
+		pass
+		{
+			ambient 0.5 0.5 0.5 1.0
+			diffuse 0.5 0.5 0.5 1.0
+			specular 0.2 0.2 0.2 1.0 12.5
+
+			texture_unit
+			{
+				texture floor.jpg
+				filtering anistropic
+				max_anisotropy 16
+				scale 0.01 0.01
+			}
+		}
+	}
+}

gazebo/models/floor/model.config

@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+
+<model>
+  <name>Floor</name>
+  <version>1.0</version>
+  <sdf version="1.5">floor.sdf</sdf>
+
+  <author>
+    <name>Oleg Kalachev</name>
+    <email>okalachev@gmail.com</email>
+  </author>
+
+  <license>Unknown</license>
+
+  <description>
+    Floor.
+  </description>
+
+</model>

gazebo/models/linnmon/linnmon.sdf

@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+<sdf version="1.5">
+	<model name="table1">
+		<static>true</static>
+		<link name="link">
+			<pose>0 0 0 0 0 0</pose>
+			<collision name="mesh">
+				<geometry>
+					<mesh>
+						<uri>model://linnmon/linnmon.dae</uri>
+					</mesh>
+				</geometry>
+			</collision>
+			<visual name="visual">
+				<geometry>
+					<mesh>
+						<uri>model://linnmon/linnmon.dae</uri>
+					</mesh>
+				</geometry>
+			</visual>
+		</link>
+	</model>
+</sdf>

gazebo/models/linnmon/model.config

@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+
+<model>
+  <name>linnmon</name>
+  <version>1.0</version>
+  <sdf version="1.5">linnmon.sdf</sdf>
+
+  <author>
+    <name>Oleg Kalachev</name>
+    <email>okalachev@gmail.com</email>
+  </author>
+
+  <license>Unknown</license>
+
+  <description>
+    Linnmon table from https://3dlancer.net/en/producermodels/tables-coffee-tables/3dmodel-table-with-ikea-linnmon-36059
+  </description>
+
+</model>

gazebo/simulator.cpp

@@ -0,0 +1,133 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Gazebo plugin for running Arduino code and simulating the drone
+
+#include <functional>
+#include <cmath>
+#include <gazebo/gazebo.hh>
+#include <gazebo/physics/physics.hh>
+#include <gazebo/common/common.hh>
+#include <gazebo/sensors/sensors.hh>
+#include <gazebo/msgs/msgs.hh>
+#include <ignition/math/Vector3.hh>
+#include <ignition/math/Pose3.hh>
+#include <iostream>
+#include <fstream>
+
+#include "Arduino.h"
+#include "flix.h"
+#include "util.h"
+#include "util.ino"
+#include "rc.ino"
+#include "time.ino"
+#include "estimate.ino"
+#include "control.ino"
+#include "log.ino"
+#include "cli.ino"
+#include "mavlink.ino"
+#include "lpf.h"
+
+using ignition::math::Vector3d;
+using namespace gazebo;
+using namespace std;
+
+class ModelFlix : public ModelPlugin {
+private:
+	physics::ModelPtr model;
+	physics::LinkPtr body;
+	sensors::ImuSensorPtr imu;
+	event::ConnectionPtr updateConnection, resetConnection;
+	transport::NodePtr nodeHandle;
+	transport::PublisherPtr motorPub[4];
+	LowPassFilter<Vector> accFilter = LowPassFilter<Vector>(0.1);
+
+public:
+	void Load(physics::ModelPtr _parent, sdf::ElementPtr /*_sdf*/) {
+		this->model = _parent;
+		this->body = this->model->GetLink("body");
+		this->imu = dynamic_pointer_cast<sensors::ImuSensor>(sensors::get_sensor(model->GetScopedName(true) + "::body::imu")); // default::flix::body::imu
+		this->updateConnection = event::Events::ConnectWorldUpdateBegin(bind(&ModelFlix::OnUpdate, this));
+		this->resetConnection = event::Events::ConnectWorldReset(bind(&ModelFlix::OnReset, this));
+		initNode();
+		Serial.begin(0);
+		gzmsg << "Flix plugin loaded" << endl;
+	}
+
+	void OnReset() {
+		attitude = Quaternion(); // reset estimated attitude
+		gzmsg << "Flix plugin reset" << endl;
+	}
+
+	void OnUpdate() {
+		__micros = model->GetWorld()->SimTime().Double() * 1000000;
+		step();
+
+		// read imu
+		gyro = flu2frd(imu->AngularVelocity());
+		acc = this->accFilter.update(flu2frd(imu->LinearAcceleration()));
+
+		// read rc
+		readRC();
+		controls[RC_CHANNEL_MODE] = 1; // 0 acro, 1 stab
+		controls[RC_CHANNEL_ARMED] = 1; // armed
+
+		estimate();
+
+		// correct yaw to the actual yaw
+		attitude.setYaw(-this->model->WorldPose().Yaw());
+
+		control();
+		parseInput();
+		processMavlink();
+
+		applyMotorForces();
+		publishTopics();
+		logData();
+	}
+
+	void applyMotorForces() {
+		// thrusts
+		const double dist = 0.035355; // motors shift from the center, m
+		const double maxThrust = 0.03 * ONE_G; // ~30 g, https://youtu.be/VtKI4Pjx8Sk?&t=78
+
+		const float scale0 = 1.0, scale1 = 1.1, scale2 = 0.9, scale3 = 1.05; // imitating motors asymmetry
+		float mfl = scale0 * maxThrust * motors[MOTOR_FRONT_LEFT];
+		float mfr = scale1 * maxThrust * motors[MOTOR_FRONT_RIGHT];
+		float mrl = scale2 * maxThrust * motors[MOTOR_REAR_LEFT];
+		float mrr = scale3 * maxThrust * motors[MOTOR_REAR_RIGHT];
+
+		body->AddLinkForce(Vector3d(0.0, 0.0, mfl), Vector3d(dist, dist, 0.0));
+		body->AddLinkForce(Vector3d(0.0, 0.0, mfr), Vector3d(dist, -dist, 0.0));
+		body->AddLinkForce(Vector3d(0.0, 0.0, mrl), Vector3d(-dist, dist, 0.0));
+		body->AddLinkForce(Vector3d(0.0, 0.0, mrr), Vector3d(-dist, -dist, 0.0));
+
+		// torque
+		const double maxTorque = 0.0024 * ONE_G; // ~24 g*cm
+		body->AddRelativeTorque(Vector3d(0.0, 0.0, scale0 * maxTorque * motors[MOTOR_FRONT_LEFT]));
+		body->AddRelativeTorque(Vector3d(0.0, 0.0, scale1 * -maxTorque * motors[MOTOR_FRONT_RIGHT]));
+		body->AddRelativeTorque(Vector3d(0.0, 0.0, scale2 * -maxTorque * motors[MOTOR_REAR_LEFT]));
+		body->AddRelativeTorque(Vector3d(0.0, 0.0, scale3 * maxTorque * motors[MOTOR_REAR_RIGHT]));
+	}
+
+	void initNode() {
+		nodeHandle = transport::NodePtr(new transport::Node());
+		nodeHandle->Init();
+		string ns = "~/" + model->GetName();
+		// create motors output topics for debugging and plotting
+		motorPub[0] = nodeHandle->Advertise<msgs::Int>(ns + "/motor0");
+		motorPub[1] = nodeHandle->Advertise<msgs::Int>(ns + "/motor1");
+		motorPub[2] = nodeHandle->Advertise<msgs::Int>(ns + "/motor2");
+		motorPub[3] = nodeHandle->Advertise<msgs::Int>(ns + "/motor3");
+	}
+
+	void publishTopics() {
+		for (int i = 0; i < 4; i++) {
+			msgs::Int msg;
+			msg.set_data(static_cast<int>(round(motors[i] * 1000)));
+			motorPub[i]->Publish(msg);
+		}
+	}
+};
+
+GZ_REGISTER_MODEL_PLUGIN(ModelFlix)

gazebo/soc/rtc_cntl_reg.h

@@ -0,0 +1 @@
+// Dummy file to make it possible to compile simulator with util.ino

gazebo/soc/soc.h

@@ -0,0 +1,3 @@
+// Dummy file to make it possible to compile simulator with util.ino
+
+#define WRITE_PERI_REG(addr, val) {}

gazebo/util.h

@@ -0,0 +1,14 @@
+#include <ignition/math/Vector3.hh>
+#include <ignition/math/Pose3.hh>
+
+using ignition::math::Vector3d;
+using ignition::math::Pose3d;
+
+Pose3d flu2frd(const Pose3d& p) {
+	return ignition::math::Pose3d(p.Pos().X(), -p.Pos().Y(), -p.Pos().Z(),
+	                              p.Rot().W(), p.Rot().X(), -p.Rot().Y(), -p.Rot().Z());
+}
+
+Vector flu2frd(const Vector3d& v) {
+	return Vector(v.X(), -v.Y(), -v.Z());
+}

gazebo/wifi.h

@@ -0,0 +1,44 @@
+// Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// sendWiFi and receiveWiFi implementations for the simulation
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <sys/poll.h>
+#include <gazebo/gazebo.hh>
+
+#define WIFI_UDP_PORT_LOCAL 14580
+#define WIFI_UDP_PORT_REMOTE 14550
+
+int wifiSocket;
+
+void setupWiFi() {
+	wifiSocket = socket(AF_INET, SOCK_DGRAM, 0);
+	sockaddr_in addr;
+	addr.sin_family = AF_INET;
+	addr.sin_addr.s_addr = INADDR_ANY;
+	addr.sin_port = htons(WIFI_UDP_PORT_LOCAL);
+	bind(wifiSocket, (sockaddr *)&addr, sizeof(addr));
+	int broadcast = 1;
+	setsockopt(wifiSocket, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof(broadcast)); // enable broadcast
+	gzmsg << "WiFi UDP socket initialized on port " << WIFI_UDP_PORT_LOCAL << " (remote port " << WIFI_UDP_PORT_REMOTE << ")" << std::endl;
+}
+
+void sendWiFi(const uint8_t *buf, int len) {
+	if (wifiSocket == 0) setupWiFi();
+	sockaddr_in addr;
+	addr.sin_family = AF_INET;
+	addr.sin_addr.s_addr = INADDR_BROADCAST; // send UDP broadcast
+	addr.sin_port = htons(WIFI_UDP_PORT_REMOTE);
+	sendto(wifiSocket, buf, len, 0, (sockaddr *)&addr, sizeof(addr));
+}
+
+int receiveWiFi(uint8_t *buf, int len) {
+	struct pollfd pfd = { .fd = wifiSocket, .events = POLLIN };
+	if (poll(&pfd, 1, 0) <= 0) return 0; // check if there is data to read
+	return recv(wifiSocket, buf, len, 0);
+}

img/gh.svg

@@ -1 +0,0 @@
-<svg width="98" height="96" xmlns="http://www.w3.org/2000/svg"><path fill-rule="evenodd" clip-rule="evenodd" d="M48.854 0C21.839 0 0 22 0 49.217c0 21.756 13.993 40.172 33.405 46.69 2.427.49 3.316-1.059 3.316-2.362 0-1.141-.08-5.052-.08-9.127-13.59 2.934-16.42-5.867-16.42-5.867-2.184-5.704-5.42-7.17-5.42-7.17-4.448-3.015.324-3.015.324-3.015 4.934.326 7.523 5.052 7.523 5.052 4.367 7.496 11.404 5.378 14.235 4.074.404-3.178 1.699-5.378 3.074-6.6-10.839-1.141-22.243-5.378-22.243-24.283 0-5.378 1.94-9.778 5.014-13.2-.485-1.222-2.184-6.275.486-13.038 0 0 4.125-1.304 13.426 5.052a46.97 46.97 0 0 1 12.214-1.63c4.125 0 8.33.571 12.213 1.63 9.302-6.356 13.427-5.052 13.427-5.052 2.67 6.763.97 11.816.485 13.038 3.155 3.422 5.015 7.822 5.015 13.2 0 18.905-11.404 23.06-22.324 24.283 1.78 1.548 3.316 4.481 3.316 9.126 0 6.6-.08 11.897-.08 13.526 0 1.304.89 2.853 3.316 2.364 19.412-6.52 33.405-24.935 33.405-46.691C97.707 22 75.788 0 48.854 0z" fill="black"/></svg>

img/tg.svg

@@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- Generator: Adobe Illustrator 21.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
-<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
-	 viewBox="0 0 54 54" style="enable-background:new 0 0 54 54;" xml:space="preserve">
-<style type="text/css">
-	.st0{fill:none;}
-</style>
-<g>
-	<rect x="-0.2" y="0.1" class="st0" width="53.8" height="53.4"/>
-	<path d="M49.7,16.5c1.3,3.1,2,6.3,2,9.7s-0.7,6.6-2,9.7c-1.3,3.1-3.1,5.7-5.3,8c-2.2,2.2-4.9,4-8,5.3c-3.1,1.3-6.3,2-9.7,2
-		c-3.4,0-6.6-0.7-9.7-2s-5.7-3.1-8-5.3c-2.2-2.2-4-4.9-5.3-8c-1.3-3.1-2-6.3-2-9.7s0.7-6.6,2-9.7c1.3-3.1,3.1-5.7,5.3-8
-		c2.2-2.2,4.9-4,8-5.3s6.3-2,9.7-2c3.4,0,6.6,0.7,9.7,2c3.1,1.3,5.7,3.1,8,5.3C46.6,10.8,48.3,13.5,49.7,16.5z M34.8,37.7l4.1-19.3
-		c0.2-0.8,0.1-1.4-0.3-1.8c-0.4-0.4-0.8-0.4-1.4-0.2l-24.1,9.3c-0.5,0.2-0.9,0.4-1.1,0.7c-0.2,0.3-0.2,0.5-0.1,0.7
-		c0.1,0.2,0.4,0.4,0.9,0.5l6.2,1.9l14.3-9c0.4-0.3,0.7-0.3,0.9-0.2c0.1,0.1,0.1,0.2-0.1,0.4L22.5,31.3L22,37.7
-		c0.4,0,0.8-0.2,1.3-0.6l3-2.9l6.2,4.6C33.8,39.5,34.5,39.1,34.8,37.7z"/>
-</g>
-</svg>

index.html

@@ -1,73 +0,0 @@
-<!DOCTYPE html>
-<html>
-	<head>
-		<title>Flix — разработка квадрокоптера с нуля</title>
-		<style>
-			body {
-				display: flex;
-				justify-content: center;
-				align-items: center;
-				background: #d9d9d7;
-				height: 100vh;
-				font-family: Helvetica, sans-serif;
-				font-size: 22px;
-				margin: 0;
-				padding: 0;
-			}
-			article {
-				max-width: 800px;
-				text-align: center;
-			}
-			img.logo {
-				margin-top: -100px;
-				max-width: 100%;
-			}
-			.github {
-				background-image: url(img/tg.svg);
-				background-repeat: no-repeat;
-				background-position: left center;
-				background-size: auto 30px;
-				padding-left: 40px;
-				vertical-align: middle;
-			}
-			a {
-				color: black;
-			}
-			a:hover {
-				color: rgb(42, 45, 183);
-			}
-			.links {
-				display: inline-block;
-				list-style-type: none;
-				margin: 0;
-				padding: 0;
-				line-height: 50px;
-			}
-			.links li {
-				display: flex;
-				align-items: center;
-			}
-			.links li img {
-				height: 30px;
-				margin-right: 10px;
-				opacity: 0.2;
-			}
-		</style>
-		<!-- 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>
-		<article>
-			<img class="logo" src="img/flix.jpg" alt="Flix, версия 0 (прототип)" title="Flix, версия 0 (прототип)">
-			<ul class="links">
-				<li>
-					<img src="img/gh.svg">
-					GitHub:&nbsp;<a href="https://github.com/okalachev/flix">github.com/okalachev/flix</a>.
-				</li>
-				<li>
-					<img src="img/tg.svg">
-					Telegram-канал:&nbsp;<a href="https://t.me/opensourcequadcopter">@opensourcequadcopter</a>.
-				</li>
-			</ul>
-		</article>
-	</body>
-</html>

tools/fft.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+
+"""Show Fast Fourier Transform plot for log entry.
+
+Usage:
+  fft.py <csv_log_file> <log_entry>
+"""
+
+import docopt
+import csv
+import numpy as np
+import matplotlib.pyplot as plt
+
+args = docopt.docopt(__doc__)
+log_file = args['<csv_log_file>']
+log_entry = args['<log_entry>']
+
+csv_reader = csv.reader(open(log_file, 'r'), delimiter=',')
+header = next(csv_reader)
+log_entry_index = header.index(log_entry)
+
+data = [[float(value) for value in row] for row in csv_reader]
+data = sorted(data, key=lambda row: row[0])
+records = [row[log_entry_index] for row in data]
+duration = data[-1][0] - data[0][0]
+sample_rate = len(data) / duration
+
+print('Duration: ', duration)
+print('Mean sample rate: ', sample_rate)
+print('Mean dt: ', 1 / sample_rate)
+
+N = int(sample_rate * duration)
+
+yf = np.fft.rfft(records)
+xf = np.fft.rfftfreq(N, 1 / sample_rate)
+
+# print out fft data
+print('Frequency, Amplitude')
+for i in range(len(xf)):
+    print(xf[i], ',', abs(yf[i]))
+
+plt.plot(xf, np.abs(yf))
+plt.title('FFT of ' + log_entry)
+plt.xlabel('Frequency')
+plt.ylabel('Amplitude')
+plt.grid(True, which='both', color='#eeeeee')
+plt.minorticks_on()
+plt.get_current_fig_manager().set_window_title(log_entry)
+plt.show()

tools/grab_log.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+# grab flight log and save to file
+
+import datetime
+import serial
+import os
+
+PORT = os.environ['PORT']
+DIR = os.path.dirname(os.path.realpath(__file__))
+
+dev = serial.Serial(port=PORT, baudrate=115200, timeout=0.5)
+lines = []
+
+print('Downloading log...')
+count = 0
+dev.write('log\n'.encode())
+while True:
+    line = dev.readline()
+    if not line:
+        break
+    lines.append(line)
+    count += 1
+    print(f'\r{count} lines', end='')
+
+# sort by timestamp
+header = lines.pop(0)
+lines.sort(key=lambda line: float(line.split(b',')[0]))
+
+log = open(f'{DIR}/log/{datetime.datetime.now().isoformat()}.csv', 'wb')
+log.writelines([header] + lines)
+print(f'\nWritten {os.path.relpath(log.name, os.curdir)}')

tools/requirements.txt

@@ -0,0 +1,2 @@
+docopt
+matplotlib