Fix mavlink disconnection in pauses in cli commands

Implement pause function that proceeds processing mavlink. Use temporal workaround for simulation, as micros function gives the same result on the same simulation step.
Use natural order of ino files includes in simulation
2026-01-10 21:16:50 +00:00 · 2025-02-28 19:25:41 +03:00 · 2025-02-28 19:06:58 +03:00 · 2025-02-28 03:17:09 +03:00 · 2025-02-28 00:51:16 +03:00 · 2025-02-26 01:08:36 +03:00
159 changed files with 16206 additions and 1364 deletions
--- a/.editorconfig
+++ b/.editorconfig
@@ -4,8 +4,12 @@ root = true
 end_of_line = lf
 insert_final_newline = true

-[*.{ino,cpp,c,h,hpp,sdf,world}]
+[*.{ino,cpp,c,h,hpp,sdf,world,json}]
 charset = utf-8
 indent_style = tab
 tab_width = 4
 trim_trailing_whitespace = true
+
+[{*.yml,*.yaml,CMakeLists.txt}]
+indent_style = space
+indent_size = 2
--- a/.gitattributes
+++ b/.gitattributes
@@ -0,0 +1,2 @@
+# https://github.com/github-linguist/linguist/blob/master/docs/overrides.md
+*.h linguist-language=C++
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -5,60 +5,81 @@ on:
    branches: [ '*' ]
  pull_request:
    branches: [ master ]
+  workflow_dispatch:

 jobs:
-  build:
+  build_linux:
    runs-on: ubuntu-latest
    steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
    - name: Install Arduino CLI
-      uses: arduino/setup-arduino-cli@v1.1.1
+      run: curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=/usr/local/bin sh
    - name: Build firmware
      run: make
+    - name: Build firmware without Wi-Fi
+      run: sed -i 's/^#define WIFI_ENABLED 1$/#define WIFI_ENABLED 0/' flix/flix.ino && make
+    - name: Check c_cpp_properties.json
+      run: tools/check_c_cpp_properties.py

  build_macos:
    runs-on: macos-latest
    steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
    - name: Install Arduino CLI
      run: brew install arduino-cli
    - name: Build firmware
      run: make
+    - name: Check c_cpp_properties.json
+      run: tools/check_c_cpp_properties.py

  build_windows:
    runs-on: windows-latest
    steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
    - name: Install Arduino CLI
      run: choco install arduino-cli
    - name: Install Make
      run: choco install make
    - name: Build firmware
      run: make
+    - name: Check c_cpp_properties.json
+      run: python3 tools/check_c_cpp_properties.py

  build_simulator:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
    steps:
-    - uses: actions/checkout@v3
+    - name: Install Arduino CLI
+      uses: arduino/setup-arduino-cli@v1.1.1
+    - uses: actions/checkout@v4
    - 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
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
      with:
        name: gazebo-plugin-binary
        path: gazebo/build/*.so
        retention-days: 1

-  # build_simulator_macos:
-  #   runs-on: macos-latest
-  #   steps:
-  #   - uses: actions/checkout@v3
-  #   - name: Install Gazebo
-  #     run: brew tap osrf/simulation && brew install gazebo11
-  #   - name: Install SDL2
-  #     run: brew install sdl2
-  #   - name: Build simulator
-  #     run: make build_simulator
+  build_simulator_macos:
+    runs-on: macos-latest
+    if: github.event_name == 'workflow_dispatch'
+    steps:
+    - name: Install Arduino CLI
+      run: brew install arduino-cli
+    - uses: actions/checkout@v4
+    - name: Clean up python binaries # Workaround for https://github.com/actions/setup-python/issues/577
+      run: |
+        rm -f /usr/local/bin/2to3*
+        rm -f /usr/local/bin/idle3*
+        rm -f /usr/local/bin/pydoc3*
+        rm -f /usr/local/bin/python3*
+        rm -f /usr/local/bin/python3*-config
+    - name: Install Gazebo
+      run: brew update && brew tap osrf/simulation && brew install gazebo11
+    - name: Install SDL2
+      run: brew install sdl2
+    - name: Build simulator
+      run: make build_simulator
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -0,0 +1,51 @@
+name: Docs
+
+on:
+  push:
+    branches: [ '*' ]
+  pull_request:
+    branches: [ master ]
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+jobs:
+  markdownlint:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install markdownlint
+      run: npm install -g markdownlint-cli2
+    - name: Run markdownlint
+      run: markdownlint-cli2 "**/*.md"
+
+  build_book:
+    runs-on: ubuntu-latest
+    needs: markdownlint
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install mdBook
+      run: cargo install mdbook --vers 0.4.43 --locked
+    - name: Build book
+      run: cd docs && mdbook build
+    - name: Upload artifact
+      uses: actions/upload-pages-artifact@v3
+      with:
+        path: docs/build
+
+  deploy:
+    if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
+    concurrency:
+      group: "pages"
+      cancel-in-progress: true
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build_book
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4
--- a/.github/workflows/tools.yml
+++ b/.github/workflows/tools.yml
@@ -0,0 +1,33 @@
+name: Build tools
+
+on:
+  push:
+    branches: [ '*' ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  csv_to_ulog:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build csv_to_ulog
+      run: cd tools/csv_to_ulog && mkdir build && cd build && cmake .. && make
+    - name: Test csv_to_ulog
+      run: |
+        cd tools/csv_to_ulog/build
+        echo -e "t,x,y,z\n0,1,2,3\n1,4,5,6" > log.csv
+        ./csv_to_ulog log.csv
+        test $(stat -c %s log.ulg) -eq 196
+  python_tools:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Python dependencies
+      run: pip install -r tools/requirements.txt
+    - name: Test csv_to_mcap tool
+      run: |
+        cd tools
+        echo -e "t,x,y,z\n0,1,2,3\n1,4,5,6" > log.csv
+        ./csv_to_mcap.py log.csv
+        test $(stat -c %s log.mcap) -eq 883
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,12 @@
 *.hex
 *.elf
-gazebo/build/
+build/
 tools/log/
 .dependencies
+.vscode/*
+!.vscode/settings.json
+!.vscode/c_cpp_properties.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+!.vscode/intellisense.h
--- a/.markdownlint.json
+++ b/.markdownlint.json
@@ -0,0 +1,67 @@
+{
+	"MD004": {
+		"style": "asterisk"
+	},
+	"MD010": false,
+	"MD013": false,
+	"MD024": false,
+	"MD033": false,
+	"MD034": false,
+	"MD044": {
+		"html_elements": false,
+		"code_blocks": false,
+		"names": [
+			"FlixPeriph",
+			"Wi-Fi",
+			"STM",
+			"Li-ion",
+			"GitHub",
+			"github.com",
+			"PPM",
+			"PWM",
+			"Futaba",
+			"S.Bus",
+			"C++",
+			"PID",
+			"Arduino IDE",
+			"Arduino",
+			"Arduino Nano",
+			"ESP32",
+			"IMU",
+			"MEMS",
+			"imu.ino",
+			"InvenSense",
+			"MPU-6050",
+			"MPU-9250",
+			"GY-91",
+			"ICM-20948",
+			"Linux",
+			"Windows",
+			"macOS",
+			"iOS",
+			"Android",
+			"Bluetooth",
+			"GPS",
+			"GPIO",
+			"USB",
+			"SPI",
+			"I²C",
+			"UART",
+			"GND",
+			"3V3",
+			"VCC",
+			"SCL",
+			"SDA",
+			"SAO",
+			"AD0",
+			"MOSI",
+			"MISO",
+			"NCS",
+			"MOSFET",
+			"ArduPilot",
+			"Betaflight",
+			"PX4"
+		]
+	},
+	"MD045": false
+}
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -0,0 +1,147 @@
+{
+	"configurations": [
+		{
+			"name": "Linux",
+			"includePath": [
+				"${workspaceFolder}/flix",
+				"${workspaceFolder}/gazebo",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/**",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/dio_qspi/include",
+				"~/Arduino/libraries/**",
+				"/usr/include/**"
+			],
+			"forcedInclude": [
+				"${workspaceFolder}/.vscode/intellisense.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32/pins_arduino.h",
+				"${workspaceFolder}/flix/cli.ino",
+				"${workspaceFolder}/flix/control.ino",
+				"${workspaceFolder}/flix/estimate.ino",
+				"${workspaceFolder}/flix/flix.ino",
+				"${workspaceFolder}/flix/imu.ino",
+				"${workspaceFolder}/flix/led.ino",
+				"${workspaceFolder}/flix/log.ino",
+				"${workspaceFolder}/flix/mavlink.ino",
+				"${workspaceFolder}/flix/motors.ino",
+				"${workspaceFolder}/flix/rc.ino",
+				"${workspaceFolder}/flix/time.ino",
+				"${workspaceFolder}/flix/wifi.ino",
+				"${workspaceFolder}/flix/parameters.ino"
+			],
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2405/bin/xtensa-esp32-elf-g++",
+			"cStandard": "c11",
+			"cppStandard": "c++17",
+			"defines": [
+				"F_CPU=240000000L",
+				"ARDUINO=10607",
+				"ARDUINO_D1_MINI32",
+				"ARDUINO_ARCH_ESP32",
+				"ARDUINO_BOARD=D1_MINI32",
+				"ARDUINO_VARIANT=d1_mini32",
+				"ARDUINO_PARTITION_default",
+				"ESP32",
+				"CORE_DEBUG_LEVEL=0",
+				"ARDUINO_USB_CDC_ON_BOOT="
+			]
+		},
+		{
+			"name": "Mac",
+			"includePath": [
+				"${workspaceFolder}/flix",
+				"${workspaceFolder}/gazebo",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/include/**",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/dio_qspi/include",
+				"~/Documents/Arduino/libraries/**",
+				"/opt/homebrew/include/**"
+			],
+			"forcedInclude": [
+				"${workspaceFolder}/.vscode/intellisense.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32/pins_arduino.h",
+				"${workspaceFolder}/flix/flix.ino",
+				"${workspaceFolder}/flix/cli.ino",
+				"${workspaceFolder}/flix/control.ino",
+				"${workspaceFolder}/flix/estimate.ino",
+				"${workspaceFolder}/flix/imu.ino",
+				"${workspaceFolder}/flix/led.ino",
+				"${workspaceFolder}/flix/log.ino",
+				"${workspaceFolder}/flix/mavlink.ino",
+				"${workspaceFolder}/flix/motors.ino",
+				"${workspaceFolder}/flix/rc.ino",
+				"${workspaceFolder}/flix/time.ino",
+				"${workspaceFolder}/flix/wifi.ino",
+				"${workspaceFolder}/flix/parameters.ino"
+			],
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2405/bin/xtensa-esp32-elf-g++",
+			"cStandard": "c11",
+			"cppStandard": "c++17",
+			"defines": [
+				"F_CPU=240000000L",
+				"ARDUINO=10607",
+				"ARDUINO_D1_MINI32",
+				"ARDUINO_ARCH_ESP32",
+				"ARDUINO_BOARD=D1_MINI32",
+				"ARDUINO_VARIANT=d1_mini32",
+				"ARDUINO_PARTITION_default",
+				"ARDUINO_FQBN=esp32:esp32:d1_mini32",
+				"ESP32",
+				"CORE_DEBUG_LEVEL=0",
+				"ARDUINO_USB_CDC_ON_BOOT="
+			]
+		},
+		{
+			"name": "Win32",
+			"includePath": [
+				"${workspaceFolder}/flix",
+				"${workspaceFolder}/gazebo",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/**",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.3-083aad99-v2/esp32/dio_qspi/include",
+				"~/Documents/Arduino/libraries/**"
+			],
+			"forcedInclude": [
+				"${workspaceFolder}/.vscode/intellisense.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.1.0/variants/d1_mini32/pins_arduino.h",
+				"${workspaceFolder}/flix/cli.ino",
+				"${workspaceFolder}/flix/control.ino",
+				"${workspaceFolder}/flix/estimate.ino",
+				"${workspaceFolder}/flix/flix.ino",
+				"${workspaceFolder}/flix/imu.ino",
+				"${workspaceFolder}/flix/led.ino",
+				"${workspaceFolder}/flix/log.ino",
+				"${workspaceFolder}/flix/mavlink.ino",
+				"${workspaceFolder}/flix/motors.ino",
+				"${workspaceFolder}/flix/rc.ino",
+				"${workspaceFolder}/flix/time.ino",
+				"${workspaceFolder}/flix/wifi.ino",
+				"${workspaceFolder}/flix/parameters.ino"
+			],
+			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2405/bin/xtensa-esp32-elf-g++.exe",
+			"cStandard": "c11",
+			"cppStandard": "c++17",
+			"defines": [
+				"F_CPU=240000000L",
+				"ARDUINO=10607",
+				"ARDUINO_D1_MINI32",
+				"ARDUINO_ARCH_ESP32",
+				"ARDUINO_BOARD=D1_MINI32",
+				"ARDUINO_VARIANT=d1_mini32",
+				"ARDUINO_PARTITION_default",
+				"ARDUINO_FQBN=esp32:esp32:d1_mini32",
+				"ESP32",
+				"CORE_DEBUG_LEVEL=0",
+				"ARDUINO_USB_CDC_ON_BOOT="
+			]
+		}
+	],
+	"version": 4
+}
--- a/.vscode/extensions.json
+++ b/.vscode/extensions.json
@@ -0,0 +1,10 @@
+{
+	// See https://go.microsoft.com/fwlink/?LinkId=827846 to learn about workspace recommendations.
+	"recommendations": [
+		"ms-vscode.cpptools",
+		"twxs.cmake",
+		"ms-vscode.cmake-tools",
+		"ms-python.python"
+	],
+	"unwantedRecommendations": []
+}
--- a/.vscode/intellisense.h
+++ b/.vscode/intellisense.h
@@ -0,0 +1,5 @@
+#ifdef __INTELLISENSE__
+	#pragma diag_suppress 144, 513
+	// diag 144: a value of type "enum <unnamed>" cannot be used to initialize an entity of type "enum <unnamed>"C/C++
+	// diag 513: a value of type "enum <unnamed>" cannot be assigned to an entity of type "enum <unnamed>"C/C++
+#endif
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -0,0 +1,25 @@
+{
+	"version": "0.2.0",
+	"configurations": [
+		{
+			"name": "Debug simulation",
+			"type": "cppdbg",
+			"request": "launch",
+			"program": "/usr/bin/gzserver",
+			"osx": {
+				"program": "/opt/homebrew/bin/gzserver",
+				"MIMode": "lldb",
+			},
+			"args": ["--verbose", "${workspaceFolder}/gazebo/flix.world"],
+			"stopAtEntry": false,
+			"cwd": "${fileDirname}",
+			"environment": [
+				{"name": "GAZEBO_MODEL_PATH", "value": "${workspaceFolder}/gazebo/models"},
+				{"name": "GAZEBO_PLUGIN_PATH", "value": "${workspaceFolder}/gazebo/build"}
+			],
+			"MIMode": "gdb",
+			"preLaunchTask": "Build simulator",
+			"externalConsole": true,
+		},
+	]
+}
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -0,0 +1,13 @@
+{
+	"C_Cpp.intelliSenseEngineFallback": "enabled",
+	"files.associations": {
+		"*.sdf": "xml",
+		"*.ino": "cpp",
+		"*.h": "cpp"
+	},
+	"C_Cpp.vcFormat.newLine.beforeOpenBrace.function": "newLine",
+	"C_Cpp.vcFormat.newLine.beforeOpenBrace.block": "sameLine",
+	"C_Cpp.vcFormat.newLine.beforeOpenBrace.lambda": "sameLine",
+	"C_Cpp.vcFormat.newLine.beforeOpenBrace.namespace": "sameLine",
+	"C_Cpp.vcFormat.newLine.beforeOpenBrace.type": "sameLine"
+}
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -0,0 +1,31 @@
+{
+	"tasks": [
+		{
+			"label": "Build firmware",
+			"type": "shell",
+			"command": "make",
+			"problemMatcher": [ "$gcc" ],
+			"presentation": { "clear": true, "showReuseMessage": false },
+		},
+		{
+			"label": "Upload firmware",
+			"type": "shell",
+			"command": "make upload",
+			"problemMatcher": [ "$gcc" ],
+			"presentation": { "clear": true, "showReuseMessage": false }
+		},
+		{
+			"label": "Build simulator",
+			"type": "shell",
+			"command": "make build_simulator",
+			"problemMatcher": [ "$gcc" ],
+			"presentation": { "clear": true, "showReuseMessage": false }
+		},
+		{
+			"label": "Clean",
+			"type": "shell",
+			"command": "make clean",
+		}
+	],
+	"version": "2.0.0"
+}
--- a/14
+++ b/14
@@ -1,5 +1,5 @@
 BOARD = esp32:esp32:d1_mini32
-PORT := $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP2104_USB_to_UART_Bridge_Controller_* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-*)
+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
@@ -13,16 +13,17 @@ monitor:

 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 install "Bolder Flight Systems SBUS"@1.0.1
-	arduino-cli lib install --git-url https://github.com/okalachev/MPU9250.git --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@3.1.0 --config-file arduino-cli.yaml
+	arduino-cli lib update-index
+	arduino-cli lib install "FlixPeriph"
+	arduino-cli lib install "MAVLink"@2.0.12
 	touch .dependencies

 gazebo/build cmake: gazebo/CMakeLists.txt
 	mkdir -p gazebo/build
 	cd gazebo/build && cmake ..

-build_simulator: gazebo/build
+build_simulator: .dependencies gazebo/build
 	make -C gazebo/build

 simulator: build_simulator
@@ -36,9 +37,6 @@ log:
 plot:
 	plotjuggler -d $(shell ls -t tools/log/*.csv | head -n1)

-docs:
-	for FILE in docs/*.d2; do d2 $$FILE; done
-
 clean:
 	rm -rf gazebo/build flix/build flix/cache .dependencies

--- a/README.md
+++ b/README.md
@@ -1,58 +1,163 @@
-# flix
+# Flix

-**flix** (*flight + X*) — making an open source ESP32-based quadcopter from scratch.
+**Flix** (*flight + X*) — making an open source ESP32-based quadcopter from scratch.

-<img src="docs/img/flix.jpg" width=500>
+<table>
+  <tr>
+    <td align=center><strong>Version 1.1</strong> (3D-printed frame)</td>
+    <td align=center><strong>Version 0</strong></td>
+  </tr>
+  <tr>
+    <td><img src="docs/img/flix1.1.jpg" width=500 alt="Flix quadcopter"></td>
+    <td><img src="docs/img/flix.jpg" width=500 alt="Flix quadcopter"></td>
+  </tr>
+</table>

 ## Features

-* Simple and clear Arduino based source code.
+* Simple and clean Arduino based source code.
 * Acro and Stabilized flight using remote control.
 * Precise simulation using Gazebo.
-* In-RAM logging.
+* [In-RAM logging](docs/log.md).
 * Command line interface through USB port.
 * Wi-Fi support.
-* ESCs with reverse mode support.
-* *Textbook and videos for students on writing a flight controller\*.*
-* *MAVLink support\*.*
-* *Completely 3D-printed frame*.*
-* *Position control and autonomous flights using external camera\**.
+* MAVLink support.
+* Control using mobile phone (with QGroundControl app).
+* Completely 3D-printed frame.
+* Textbook for students on writing a flight controller ([in development](https://quadcopter.dev)).
+* *Position control and autonomous flights using external camera¹*.
 * [Building and running instructions](docs/build.md).

-*\* — planned.*
+*¹ — planned.*

 ## It actually flies

+See detailed demo video (for version 0): https://youtu.be/8GzzIQ3C6DQ.
+
 <a href="https://youtu.be/8GzzIQ3C6DQ"><img width=500 src="https://i3.ytimg.com/vi/8GzzIQ3C6DQ/maxresdefault.jpg"></a>

-See YouTube demo video: https://youtu.be/8GzzIQ3C6DQ.
+Version 1 test flight: https://t.me/opensourcequadcopter/42.
+
+<a href="https://t.me/opensourcequadcopter/42"><img width=500 src="docs/img/flight-video.jpg"></a>
+
+See the [user builds gallery](docs/user.md).
+
+<img src="docs/img/user/user.jpg" width=400>

 ## Simulation

-Simulation in Gazebo using a plugin that runs original Arduino code is implemented:
+The simulator is implemented using Gazebo and runs the original Arduino code:

-<img src="docs/img/simulator.png" width=500>
+<img src="docs/img/simulator.png" width=500 alt="Flix simulator">

-## Schematics
+See [instructions on running the simulation](docs/build.md).

-<img src="docs/img/schematics.svg" width=800>
+## Components (version 1)
+
+|Type|Part|Image|Quantity|
+|-|-|:-:|:-:|
+|Microcontroller board|ESP32 Mini|<img src="docs/img/esp32.jpg" width=100>|1|
+|IMU (and barometer²) board|GY‑91 (or other MPU‑9250/MPU‑6500 board), ICM‑20948³|<img src="docs/img/gy-91.jpg" width=90 align=center><img src="docs/img/icm-20948.jpg" width=100>|1|
+|Motor|8520 3.7V brushed motor (shaft 0.8mm).<br>Motor with exact 3.7V voltage is needed, not ranged working voltage (3.7V — 6V).|<img src="docs/img/motor.jpeg" width=100>|4|
+|Propeller|Hubsan 55 mm|<img src="docs/img/prop.jpg" width=100>|4|
+|MOSFET (transistor)|100N03A or [analog](https://t.me/opensourcequadcopter/33)|<img src="docs/img/100n03a.jpg" width=100>|4|
+|Pull-down resistor|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|4|
+|3.7V Li-Po battery|LW 952540 (or any compatible by the size)|<img src="docs/img/battery.jpg" width=100>|1|
+|Battery connector cable|MX2.0 2P female|<img src="docs/img/mx.png" width=100>|1|
+|Li-Po Battery charger|Any|<img src="docs/img/charger.jpg" width=100>|1|
+|Screws for IMU board mounting|M3x5|<img src="docs/img/screw-m3.jpg" width=100>|2|
+|Screws for frame assembly|M1.4x5|<img src="docs/img/screw-m1.4.jpg" height=30 align=center>|4|
+|Frame bottom part|3D printed⁴:<br>[`flix-frame-1.1.stl`](docs/assets/flix-frame-1.1.stl) [`flix-frame-1.1.step`](docs/assets/flix-frame-1.1.step)|<img src="docs/img/frame1.jpg" width=100>|1|
+|Frame top part|3D printed:<br>[`esp32-holder.stl`](docs/assets/esp32-holder.stl) [`esp32-holder.step`](docs/assets/esp32-holder.step)|<img src="docs/img/esp32-holder.jpg" width=100>|1|
+|Washer for IMU board mounting|3D printed:<br>[`washer-m3.stl`](docs/assets/washer-m3.stl) [`washer-m3.step`](docs/assets/washer-m3.step)|<img src="docs/img/washer-m3.jpg" width=100>|2|
+|*RC transmitter (optional)*|*KINGKONG TINY X8 or other⁵*|<img src="docs/img/tx.jpg" width=100>|1|
+|*RC receiver (optional)*|*DF500 or other⁵*|<img src="docs/img/rx.jpg" width=100>|1|
+|Wires|28 AWG recommended|<img src="docs/img/wire-28awg.jpg" width=100>||
+|Tape, double-sided tape||||
+
+*² — barometer is not used for now.*<br>
+*³ — change `MPU9250` to `ICM20948` in `imu.ino` file if using ICM-20948 board.*<br>
+*⁴ — this frame is optimized for GY-91 board, if using other, the board mount holes positions should be modified.*<br>
+*⁵ — you may use any transmitter-receiver pair with SBUS interface.*
+
+Tools required for assembly:
+
+* 3D printer.
+* Soldering iron.
+* Solder wire (with flux).
+* Screwdrivers.
+* Multimeter.
+
+Feel free to modify the design and or code, and create your own improved versions of Flix! Send your results to the [official Telegram chat](https://t.me/opensourcequadcopterchat), or directly to the author ([E-mail](mailto:okalachev@gmail.com), [Telegram](https://t.me/okalachev)).
+
+## Schematics (version 1)
+
+### Simplified connection diagram
+
+<img src="docs/img/schematics1.svg" width=800 alt="Flix version 1 schematics">
+
+Motor connection scheme:
+
+<img src="docs/img/mosfet-connection.png" height=400 alt="MOSFET connection scheme">
+
+You can see a user-contributed [variant of complete circuit diagram](https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612338222067&cot=14) of the drone.
+
+See [assembly guide](docs/assembly.md) for instructions on assembling the drone.
+
+### Notes
+
+* Power ESP32 Mini with Li-Po battery using VCC (+) and GND (-) pins.
+* Connect the IMU board to the ESP32 Mini using VSPI, power it using 3.3V and GND pins:
+
+  |IMU pin|ESP32 pin|
+  |-|-|
+  |GND|GND|
+  |3.3V|3.3V|
+  |SCL *(SCK)*|SVP (GPIO18)|
+  |SDA *(MOSI)*|GPIO23|
+  |SAO *(MISO)*|GPIO19|
+  |NCS|GPIO5|
+
+* Solder pull-down resistors to the MOSFETs.
+* Connect the motors to the ESP32 Mini using MOSFETs, by following scheme:
+
+  |Motor|Position|Direction|Wires|GPIO|
+  |-|-|-|-|-|
+  |Motor 0|Rear left|Counter-clockwise|Black & White|GPIO12 (*TDI*)|
+  |Motor 1|Rear right|Clockwise|Blue & Red|GPIO13 (*TCK*)|
+  |Motor 2|Front right|Counter-clockwise|Black & White|GPIO14 (*TMS*)|
+  |Motor 3|Front left|Clockwise|Blue & Red|GPIO15 (*TD0*)|
+
+  Counter-clockwise motors have black and white wires and clockwise motors have blue and red wires.
+
+* Optionally connect the RC receiver to the ESP32's UART2:
+
+  |Receiver pin|ESP32 pin|
+  |-|-|
+  |GND|GND|
+  |VIN|VCC (or 3.3V depending on the receiver)|
+  |Signal (TX)|GPIO4⁶|
+
+*⁶ — UART2 RX pin was [changed](https://docs.espressif.com/projects/arduino-esp32/en/latest/migration_guides/2.x_to_3.0.html#id14) to GPIO4 in Arduino ESP32 core 3.0.*
+
+### IMU placement
+
+Default IMU orientation in the code is **LFD** (Left-Forward-Down):
+
+<img src="docs/img/gy91-lfd.svg" width=400 alt="GY-91 axes">
+
+In case of using other IMU orientation, modify the `rotateIMU` function in the `imu.ino` file.
+
+See [FlixPeriph documentation](https://github.com/okalachev/flixperiph?tab=readme-ov-file#imu-axes-orientation) to learn axis orientation of other IMU boards.

 ## Version 0

-### Components
+See the information on the obsolete version 0 in the [corresponding article](docs/version0.md).

-|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|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||
+## Materials
+
+Subscribe to the Telegram channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
+
+Join the official Telegram chat: https://t.me/opensourcequadcopterchat.
+
+Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.
--- a/arduino-cli.yaml
+++ b/arduino-cli.yaml
@@ -1,5 +1,3 @@
 board_manager:
  additional_urls:
    - https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
-library:
-  enable_unsafe_install: true
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -0,0 +1,10 @@
+build:
+	mdbook build
+
+serve:
+	mdbook serve
+
+clean:
+	mdbook clean
+
+.PHONY: build serve clean
--- a/docs/alerts.py
+++ b/docs/alerts.py
@@ -0,0 +1,31 @@
+# https://rust-lang.github.io/mdBook/format/configuration/preprocessors.html
+# https://rust-lang.github.io/mdBook/for_developers/preprocessors.html
+
+import json
+import sys
+import re
+
+
+def transform_markdown_to_html(markdown_text):
+    def replace_blockquote(match):
+        tag = match.group(1).lower()
+        content = match.group(2).strip().replace('\n> ', ' ')
+        return f'<div class="alert alert-{tag}">{content}</div>\n'
+
+    pattern = re.compile(r'> \[!(NOTE|TIP|IMPORTANT|WARNING|CAUTION)\]\n>(.*?)\n?(?=(\n[^>]|\Z))', re.DOTALL)
+    transformed_text = pattern.sub(replace_blockquote, markdown_text)
+    return transformed_text
+
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1:
+        if sys.argv[1] == 'supports':
+            sys.exit(0)
+
+    context, book = json.load(sys.stdin)
+
+    for section in book['sections']:
+        if 'Chapter' in section:
+            section['Chapter']['content'] = transform_markdown_to_html(section['Chapter']['content'])
+
+    print(json.dumps(book))
--- a/docs/assembly.md
+++ b/docs/assembly.md
@@ -0,0 +1,29 @@
+# Brief assembly guide
+
+Soldered components ([schematics variant](https://miro.com/app/board/uXjVN-dTjoo=/?moveToWidget=3458764612338222067&cot=14)):
+
+<img src="img/assembly/1.jpg" width=600>
+
+<br>Use double-sided tape to attach ESP32 to the top frame part (ESP32 holder):
+
+<img src="img/assembly/2.jpg" width=600>
+
+<br>Use two washers to screw the IMU board to the frame:
+
+<img src="img/assembly/3.jpg" width=600>
+
+<br>Screw the IMU with M3x5 screws as shown:
+
+<img src="img/assembly/4.jpg" width=600>
+
+<br>Install the motors, attach MOSFETs to the frame using tape:
+
+<img src="img/assembly/5.jpg" width=600>
+
+<br>Screw the ESP32 holder with M1.4x5 screws to the frame:
+
+<img src="img/assembly/6.jpg" width=600>
+
+<br>Assembled drone:
+
+<img src="img/assembly/7.jpg" width=600>
--- a/docs/assets/esp32-holder.step
+++ b/docs/assets/esp32-holder.step
--- a/docs/assets/esp32-holder.stl
+++ b/docs/assets/esp32-holder.stl
--- a/docs/assets/flix-frame-1.1.step
+++ b/docs/assets/flix-frame-1.1.step
--- a/docs/assets/flix-frame-1.1.stl
+++ b/docs/assets/flix-frame-1.1.stl
--- a/docs/assets/flix-frame.step
+++ b/docs/assets/flix-frame.step
--- a/docs/assets/flix-frame.stl
+++ b/docs/assets/flix-frame.stl
--- a/docs/assets/washer-m3.step
+++ b/docs/assets/washer-m3.step
@@ -0,0 +1,200 @@
+ISO-10303-21;
+HEADER;
+
+FILE_DESCRIPTION(
+/* description */ (''),
+/* implementation_level */ '2;1');
+
+FILE_NAME(
+/* name */ 'washer-m3.step',
+/* time_stamp */ '2024-10-29T13:59:42+03:00',
+/* author */ (''),
+/* organization */ (''),
+/* preprocessor_version */ '',
+/* originating_system */ '',
+
+/* authorisation */ '');
+
+FILE_SCHEMA (('AUTOMOTIVE_DESIGN { 1 0 10303 214 3 1 1 }'));
+ENDSEC;
+
+DATA;
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+#143=SURFACE_SIDE_STYLE('',(#144));
+#144=SURFACE_STYLE_FILL_AREA(#145);
+#145=FILL_AREA_STYLE('Steel - Satin',(#146));
+#146=FILL_AREA_STYLE_COLOUR('Steel - Satin',#147);
+#147=COLOUR_RGB('Steel - Satin',0.627450980392157,0.627450980392157,0.627450980392157);
+ENDSEC;
+END-ISO-10303-21;
--- a/docs/assets/washer-m3.stl
+++ b/docs/assets/washer-m3.stl
--- a/docs/book.css
+++ b/docs/book.css
@@ -0,0 +1,110 @@
+.sidebar-resize-handle { display: none !important; }
+
+footer {
+	contain: content;
+	border-top: 3px solid #f4f4f4;
+}
+
+footer a.telegram, footer a.github {
+	display: block;
+	margin-bottom: 10px;
+	margin-top: 10px;
+	display: flex;
+	align-items: center;
+	text-decoration: none;
+}
+
+.content .github, .content .telegram {
+	display: flex;
+	align-items: center;
+	text-align: center;
+	justify-content: center;
+}
+
+.telegram::before, .github::before {
+	font-family: FontAwesome;
+	margin-right: 0.3em;
+	font-size: 1.6em;
+	color: black;
+}
+
+.github::before {
+	content: "\f09b";
+}
+
+.telegram::before {
+	font-size: 1.4em;
+	color: #0084c5;
+	content: "\f2c6";
+}
+
+.content hr {
+	border: none;
+	border-top: 2px solid #c9c9c9;
+	margin: 2em 0;
+}
+
+.content img {
+	display: block;
+	margin: 0 auto;
+}
+
+.content img.border {
+	border: 1px solid #c9c9c9;
+}
+
+.firmware {
+	position: relative;
+	margin: 20px 0;
+	padding: 20px 20px;
+	padding-left: 60px;
+	color: var(--fg);
+	background-color: var(--quote-bg);
+	border-block-start: .1em solid var(--quote-border);
+	border-block-end: .1em solid var(--quote-border);
+}
+
+.firmware::before {
+	font-family: FontAwesome;
+	font-size: 1.5em;
+	content: "\f15b";
+	position: absolute;
+	width: 20px;
+	text-align: center;
+	left: 20px;
+}
+
+.alert {
+	margin-top: 20px;
+	margin-bottom: 20px;
+	position: relative;
+	border-left: 2px solid #0a69da;
+	padding: 20px;
+	padding-left: 60px;
+}
+
+.alert::before {
+	font-family: FontAwesome;
+	font-size: 1.5em;
+	color: #0a69da;
+	content: "\f05a";
+	position: absolute;
+	width: 20px;
+	text-align: center;
+	left: 20px;
+}
+
+.alert-tip { border-left-color: #1b7f37; }
+.alert-tip::before { color: #1b7f37; content: '\f0eb'; }
+
+.alert-caution { border-left-color: #cf212e; }
+.alert-caution::before { color: #cf212e; content: '\f071'; }
+
+.alert-important { border-left-color: #8250df; }
+.alert-important::before { color: #8250df; content: '\f06a'; }
+
+.alert-warning { border-left-color: #f0ad4e; }
+.alert-warning::before { color: #f0ad4e; content: '\f071'; }
+
+.alert-code { border-left-color: #333; }
+.alert-code::before { color: #333; content: '\f121'; }
--- a/docs/book.toml
+++ b/docs/book.toml
@@ -0,0 +1,22 @@
+[book]
+authors = ["Oleg Kalachev"]
+language = "ru"
+multilingual = false
+src = "book"
+title = "Полетный контроллер с нуля"
+description = "Учебник по разработке полетного контроллера квадрокоптера"
+
+[build]
+build-dir = "build"
+
+[output.html]
+additional-css = ["book.css", "zoom.css"]
+additional-js = ["zoom.js", "js.js"]
+edit-url-template = "https://github.com/okalachev/flix/blob/master/docs/{path}?plain=1"
+mathjax-support = true
+
+[output.html.code.hidelines]
+cpp = "//~"
+
+[preprocessor.alerts]
+command = "python3 alerts.py"
--- a/docs/book/README.md
+++ b/docs/book/README.md
@@ -0,0 +1,10 @@
+# Flix
+
+> [!IMPORTANT]
+> Flix — это проект по созданию открытого квадрокоптера на базе ESP32 с нуля и учебника по разработке полетных контроллеров.
+
+<img src="img/flix1.1.jpg" class="border" width=500 alt="Flix quadcopter">
+
+<p class="github">GitHub:&nbsp;<a href="https://github.com/okalachev/flix">github.com/okalachev/flix</a>.</p>
+
+<p class="telegram">Telegram-канал:&nbsp;<a href="https://t.me/opensourcequadcopter">@opensourcequadcopter</a>.</p>
--- a/docs/book/SUMMARY.md
+++ b/docs/book/SUMMARY.md
@@ -0,0 +1,22 @@
+<!-- markdownlint-disable MD041 -->
+<!-- markdownlint-disable MD042 -->
+
+[Главная](./README.md)
+
+* [Архитектура прошивки](firmware.md)
+
+# Учебник
+
+* [Основы]()
+* [Светодиод]()
+* [Моторы]()
+* [Радиоуправление]()
+* [Гироскоп](gyro.md)
+* [Акселерометр]()
+* [Оценка состояния]()
+* [PID-регулятор]()
+* [Режим ACRO]()
+* [Режим STAB]()
+* [Wi-Fi]()
+* [MAVLink]()
+* [Симуляция]()
--- a/docs/book/firmware.md
+++ b/docs/book/firmware.md
@@ -0,0 +1,32 @@
+# Архитектура прошивки
+
+<img src="img/dataflow.svg" width=800 alt="Firmware dataflow diagram">
+
+Главный цикл работает на частоте 1000 Гц. Передача данных между подсистемами происходит через глобальные переменные:
+
+* `t` *(float)* — текущее время шага, *с*.
+* `dt` *(float)* — дельта времени между текущим и предыдущим шагами, *с*.
+* `gyro` *(Vector)* — данные с гироскопа, *рад/с*.
+* `acc` *(Vector)* — данные с акселерометра, *м/с<sup>2</sup>*.
+* `rates` *(Vector)* — отфильтрованные угловые скорости, *рад/с*.
+* `attitude` *(Quaternion)* — оценка ориентации (положения) дрона.
+* `controls` *(float[])* — пользовательские управляющие сигналы с пульта, нормализованные в диапазоне [-1, 1].
+* `motors` *(float[])* — выходные сигналы на моторы, нормализованные в диапазоне [-1, 1] (возможно вращение в обратную сторону).
+
+## Исходные файлы
+
+Исходные файлы прошивки находятся в директории `flix`. Ключевые файлы:
+
+* [`flix.ino`](https://github.com/okalachev/flix/blob/canonical/flix/flix.ino) — основной входной файл, скетч Arduino. Включает определение глобальных переменных и главный цикл.
+* [`imu.ino`](https://github.com/okalachev/flix/blob/canonical/flix/imu.ino) — чтение данных с датчика IMU (гироскоп и акселерометр), калибровка IMU.
+* [`rc.ino`](https://github.com/okalachev/flix/blob/canonical/flix/rc.ino) — чтение данных с RC-приемника, калибровка RC.
+* [`mavlink.ino`](https://github.com/okalachev/flix/blob/canonical/flix/mavlink.ino) — взаимодействие с QGroundControl через MAVLink.
+* [`estimate.ino`](https://github.com/okalachev/flix/blob/canonical/flix/estimate.ino) — оценка ориентации дрона, комплементарный фильтр.
+* [`control.ino`](https://github.com/okalachev/flix/blob/canonical/flix/control.ino) — управление ориентацией и угловыми скоростями дрона, трехмерный двухуровневый каскадный PID-регулятор.
+* [`motors.ino`](https://github.com/okalachev/flix/blob/canonical/flix/motors.ino) — управление выходными сигналами на моторы через ШИМ.
+
+Вспомогательные файлы включают:
+
+* [`vector.h`](https://github.com/okalachev/flix/blob/canonical/flix/vector.h), [`quaternion.h`](https://github.com/okalachev/flix/blob/canonical/flix/quaternion.h) — реализация библиотек векторов и кватернионов проекта.
+* [`pid.h`](https://github.com/okalachev/flix/blob/canonical/flix/pid.h) — реализация общего ПИД-регулятора.
+* [`lpf.h`](https://github.com/okalachev/flix/blob/canonical/flix/lpf.h) — реализация общего фильтра нижних частот.
--- a/docs/book/gyro.md
+++ b/docs/book/gyro.md
@@ -0,0 +1,262 @@
+# Гироскоп
+
+<div class="firmware">
+	<strong>Файл прошивки Flix:</strong>
+	<a href="https://github.com/okalachev/flix/blob/canonical/flix/imu.ino"><code>imu.ino</code></a> <small>(каноничная версия)</small>.<br>
+	Текущая версия: <a href="https://github.com/okalachev/flix/blob/master/flix/imu.ino"><code>imu.ino</code></a>.
+</div>
+
+Поддержание стабильного полета квадрокоптера невозможно без датчиков обратной связи. Важнейший из них — это **MEMS-гироскоп**. MEMS-гироскоп это микроэлектромеханический аналог классического механического гироскопа.
+
+Механический гироскоп состоит из вращающегося диска, который сохраняет свою ориентацию в пространстве. Благодаря этому эффекту возможно определить ориентацию объекта в пространстве.
+
+В MEMS-гироскопе нет вращающихся частей, и он помещается в крошечную микросхему. Он может измерять только текущую угловую скорость вращения объекта вокруг трех осей: X, Y и Z.
+
+|Механический гироскоп|MEMS-гироскоп|
+|-|-|
+|<img src="img/gyroscope.jpg" width="300" alt="Механический гироскоп">|<img src="img/mpu9250.jpg" width="100" alt="MEMS-гироскоп MPU-9250">|
+
+MEMS-гироскоп обычно интегрирован в инерциальный модуль (IMU), в котором также находятся акселерометр и магнитометр. Модуль IMU часто называют 9-осевым датчиком, потому что он измеряет:
+
+* Угловую скорость вращения по трем осям (гироскоп).
+* Ускорение по трем осям (акселерометр).
+* Магнитное поле по трем осям (магнитометр).
+
+Flix поддерживает следующие модели IMU:
+
+* InvenSense MPU-9250.
+* InvenSense MPU-6500.
+* InvenSense ICM-20948.
+
+> [!NOTE]
+> MEMS-гироскоп измеряет угловую скорость вращения объекта.
+
+## Интерфейс подключения
+
+Большинство модулей IMU подключаются к микроконтроллеру через интерфейсы I²C и SPI. Оба этих интерфейса являются *шинами данных*, то есть позволяют подключить к одному микроконтроллеру несколько устройств.
+
+**Интерфейс I²C** использует два провода для передачи данных и тактового сигнала. Выбор устройства для коммуникации происходит при помощи передачи адреса устройства на шину. Разные устройства имеют разные адреса, и микроконтроллер может последовательно общаться с несколькими устройствами.
+
+**Интерфейс SPI** использует два провода для передачи данных, еще один для тактового сигнала и еще один для выбора устройства. При этом для каждого устройства на шине выделяется отдельный GPIO-пин для выбора. В разных реализациях этот пин называется CS/NCS (Chip Select) или SS (Slave Select). Когда CS-пин устройства активен (напряжение на нем низкое), устройство выбрано для общения.
+
+В полетных контроллерах IMU обычно подключают через SPI, потому что он обеспечивает значительно бо́льшую скорость передачи данных и меньшую задержку. Подключение IMU через интерфейс I²C (например, в случае нехватки пинов микроконтроллера) возможно, но не рекомендуется.
+
+Подключение IMU к микроконтроллеру ESP32 через интерфейс SPI выглядит так:
+
+|Пин платы IMU|Пин ESP32|
+|-|-|
+|VCC/3V3|3V3|
+|GND|GND|
+|SCL|IO18|
+|SDA *(MOSI)*|IO23|
+|SAO/AD0 *(MISO)*|IO19|
+|NCS|IO5|
+
+Кроме того, многие IMU могут «будить» микроконтроллер при наличии новых данных. Для этого используется пин INT, который подключается к любому GPIO-пину микроконтроллера. При такой конфигурации можно использовать прерывания для обработки новых данных с IMU, вместо периодического опроса датчика. Это позволяет снизить нагрузку на микроконтроллер в сложных алгоритмах управления.
+
+> [!WARNING]
+> На некоторых платах IMU, например, на ICM-20948, отсутствует стабилизатор напряжения, поэтому их нельзя подключать к пину VIN ESP32, который подает напряжение 5 В. Допустимо питание только от пина 3V3.
+
+## Работа с гироскопом
+
+Для взаимодействия с IMU, включая работу с гироскопом, в Flix используется библиотека *FlixPeriph*. Библиотека устанавливается через менеджер библиотек Arduino IDE:
+
+<img src="img/flixperiph.png" width="300">
+
+Чтобы работать с IMU, используется класс, соответствующий модели IMU: `MPU9250`, `MPU6500` или `ICM20948`. Классы для работы с разными IMU имеют единообразный интерфейс для основных операций, поэтому возможно легко переключаться между разными моделями IMU. Датчик MPU-6500 практически полностью совместим с MPU-9250, поэтому фактически класс `MPU9250` поддерживает обе модели.
+
+## Ориентация осей гироскопа
+
+Данные с гироскопа представляют собой угловую скорость вокруг трех осей: X, Y и Z. Ориентацию этих осей у IMU InvenSense можно легко определить по небольшой точке в углу чипа. Оси координат и направление вращения для измерений гироскопа обозначены на диаграмме:
+
+<img src="img/imu-axes.svg" width="300" alt="Оси координат IMU">
+
+Расположение осей координат в популярных платах IMU:
+
+|GY-91|MPU-92/65|ICM-20948|
+|-|-|-|
+|<img src="https://github.com/okalachev/flixperiph/raw/refs/heads/master/img/gy91-axes.svg" width="200" alt="Оси координат платы GY-91">|<img src="https://github.com/okalachev/flixperiph/raw/refs/heads/master/img/mpu9265-axes.svg" width="200" alt="Оси координат платы MPU-9265">|<img src="https://github.com/okalachev/flixperiph/raw/refs/heads/master/img/icm20948-axes.svg" width="200" alt="Оси координат платы ICM-20948">|
+
+Магнитометр IMU InvenSense обычно является отдельным устройством, интегрированным в чип, поэтому его оси координат могут отличаться. Библиотека FlixPeriph скрывает это различие и приводит данные с магнитометра к системе координат гироскопа и акселерометра.
+
+## Чтение данных
+
+Интерфейс библиотеки FlixPeriph соответствует стилю, принятому в Arduino. Для начала работы с IMU необходимо создать объект соответствующего класса и вызвать метод `begin()`. В конструктор класса передается интерфейс, по которому подключен IMU (SPI или I²C):
+
+```cpp
+#include <FlixPeriph.h>
+#include <SPI.h>
+
+MPU9250 IMU(SPI);
+
+void setup() {
+	Serial.begin(115200);
+	bool success = IMU.begin();
+	if (!success) {
+		Serial.println("Failed to initialize IMU");
+	}
+}
+```
+
+Для однократного считывания данных используется метод `read()`. Затем данные с гироскопа получаются при помощи метода `getGyro(x, y, z)`. Этот метод записывает в переменные `x`, `y` и `z` угловые скорости вокруг соответствующих осей в радианах в секунду.
+
+Если нужно гарантировать, что будут считаны новые данные, можно использовать метод `waitForData()`. Этот метод блокирует выполнение программы до тех пор, пока в IMU не появятся новые данные. Метод `waitForData()` позволяет привязать частоту главного цикла `loop` к частоте обновления данных IMU. Это удобно для организации главного цикла управления квадрокоптером.
+
+Программа для чтения данных с гироскопа и вывода их в консоль для построения графиков в Serial Plotter выглядит так:
+
+```cpp
+#include <FlixPeriph.h>
+#include <SPI.h>
+
+MPU9250 IMU(SPI);
+
+void setup() {
+	Serial.begin(115200);
+	bool success = IMU.begin();
+	if (!success) {
+		Serial.println("Failed to initialize IMU");
+	}
+}
+
+void loop() {
+	IMU.waitForData();
+
+	float gx, gy, gz;
+	IMU.getGyro(gx, gy, gz);
+
+	Serial.printf("gx:%f gy:%f gz:%f\n", gx, gy, gz);
+	delay(50); // замедление вывода
+}
+```
+
+После запуска программы в Serial Plotter можно увидеть графики угловых скоростей. Например, при вращениях IMU вокруг вертикальной оси Z графики будут выглядеть так:
+
+<img src="img/gyro-plotter.png">
+
+## Конфигурация гироскопа
+
+В коде Flix настройка IMU происходит в функции `configureIMU`. В этой функции настраиваются три основных параметра гироскопа: диапазон измерений, частота сэмплов и частота LPF-фильтра.
+
+### Частота сэмплов
+
+Большинство IMU могут обновлять данные с разной частотой. В полетных контроллерах обычно используется частота обновления от 500 Гц до 8 кГц. Чем выше частота сэмплов, тем выше точность управления полетом, но и больше нагрузка на микроконтроллер.
+
+Частота сэмплов устанавливается методом `setSampleRate()`. В Flix используется частота 1 кГц:
+
+```cpp
+IMU.setRate(IMU.RATE_1KHZ_APPROX);
+```
+
+Поскольку не все поддерживаемые IMU могут работать строго на частоте 1 кГц, в библиотеке FlixPeriph существует возможность приближенной настройки частоты сэмплов. Например, у IMU ICM-20948 при такой настройке реальная частота сэмплирования будет равна 1125 Гц.
+
+Другие доступные для установки в библиотеке FlixPeriph частоты сэмплирования:
+
+* `RATE_MIN` — минимальная частота сэмплов для конкретного IMU.
+* `RATE_50HZ_APPROX` — значение, близкое к 50 Гц.
+* `RATE_1KHZ_APPROX`  — значение, близкое к 1 кГц.
+* `RATE_8KHZ_APPROX` — значение, близкое к 8 кГц.
+* `RATE_MAX` — максимальная частота сэмплов для конкретного IMU.
+
+#### Диапазон измерений
+
+Большинство MEMS-гироскопов поддерживают несколько диапазонов измерений угловой скорости. Главное преимущество выбора меньшего диапазона — бо́льшая чувствительность. В полетных контроллерах обычно выбирается максимальный диапазон измерений от –2000 до 2000 градусов в секунду, чтобы обеспечить возможность динамичных маневров.
+
+В библиотеке FlixPeriph диапазон измерений гироскопа устанавливается методом `setGyroRange()`:
+
+```cpp
+IMU.setGyroRange(IMU.GYRO_RANGE_2000DPS);
+```
+
+### LPF-фильтр
+
+IMU InvenSense могут фильтровать измерения на аппаратном уровне при помощи фильтра нижних частот (LPF). Flix реализует собственный фильтр для гироскопа, чтобы иметь больше гибкости при поддержке разных IMU. Поэтому для встроенного LPF устанавливается максимальная частота среза:
+
+```cpp
+IMU.setDLPF(IMU.DLPF_MAX);
+```
+
+## Калибровка гироскопа
+
+Как и любое измерительное устройство, гироскоп вносит искажения в измерения. Наиболее простая модель этих искажений делит их на статические смещения (*bias*) и случайный шум (*noise*):
+
+\\[ gyro_{xyz}=rates_{xyz}+bias_{xyz}+noise \\]
+
+Для качественной работы подсистемы оценки ориентации и управления дроном необходимо оценить *bias* гироскопа и учесть его в вычислениях. Для этого при запуске программы производится калибровка гироскопа, которая реализована в функции `calibrateGyro()`. Эта функция считывает данные с гироскопа в состоянии покоя 1000 раз и усредняет их. Полученные значения считаются *bias* гироскопа и в дальнейшем вычитаются из измерений.
+
+Программа для вывода данных с гироскопа с калибровкой:
+
+```cpp
+#include <FlixPeriph.h>
+#include <SPI.h>
+
+MPU9250 IMU(SPI);
+
+float gyroBiasX, gyroBiasY, gyroBiasZ; // bias гироскопа
+
+void setup() {
+	Serial.begin(115200);
+	bool success = IMU.begin();
+	if (!success) {
+		Serial.println("Failed to initialize IMU");
+	}
+	calibrateGyro();
+}
+
+void loop() {
+	float gx, gy, gz;
+	IMU.waitForData();
+	IMU.getGyro(gx, gy, gz);
+
+	// Устранение bias гироскопа
+	gx -= gyroBiasX;
+	gy -= gyroBiasY;
+	gz -= gyroBiasZ;
+
+	Serial.printf("gx:%f gy:%f gz:%f\n", gx, gy, gz);
+	delay(50); // замедление вывода
+}
+
+void calibrateGyro() {
+	const int samples = 1000;
+	Serial.println("Calibrating gyro, stand still");
+
+	gyroBiasX = 0;
+	gyroBiasY = 0;
+	gyroBiasZ = 0;
+
+	// Получение 1000 измерений гироскопа
+	for (int i = 0; i < samples; i++) {
+		IMU.waitForData();
+		float gx, gy, gz;
+		IMU.getGyro(gx, gy, gz);
+		gyroBiasX += gx;
+		gyroBiasY += gy;
+		gyroBiasZ += gz;
+	}
+
+	// Усреднение значений
+	gyroBiasX = gyroBiasX / samples;
+	gyroBiasY = gyroBiasY / samples;
+	gyroBiasZ = gyroBiasZ / samples;
+
+	Serial.printf("Gyro bias X: %f\n", gyroBiasX);
+	Serial.printf("Gyro bias Y: %f\n", gyroBiasY);
+	Serial.printf("Gyro bias Z: %f\n", gyroBiasZ);
+}
+```
+
+График данных с гироскопа в состоянии покоя без калибровки. Можно увидеть статическую ошибку каждой из осей:
+
+<img src="img/gyro-uncalibrated-plotter.png">
+
+График данных с гироскопа в состоянии покоя после калибровки:
+
+<img src="img/gyro-calibrated-plotter.png">
+
+Откалиброванные данные с гироскопа вместе с данными с акселерометра поступают в *подсистему оценки состояния*.
+
+## Дополнительные материалы
+
+* [MPU-9250 datasheet](https://invensense.tdk.com/wp-content/uploads/2015/02/PS-MPU-9250A-01-v1.1.pdf).
+* [MPU-6500 datasheet](https://invensense.tdk.com/wp-content/uploads/2020/06/PS-MPU-6500A-01-v1.3.pdf).
+* [ICM-20948 datasheet](https://invensense.tdk.com/wp-content/uploads/2016/06/DS-000189-ICM-20948-v1.3.pdf).
--- a/docs/book/img
+++ b/docs/book/img
@@ -0,0 +1 @@
+../img
--- a/docs/build.md
+++ b/docs/build.md
@@ -1,12 +1,25 @@
 # 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

-Dependencies are [Gazebo Classic simulator](https://classic.gazebosim.org) and [SDL2](https://www.libsdl.org) library.
+### Ubuntu 20.04

-### Ubuntu
+The latest version of Ubuntu supported by Gazebo 11 simulator is 20.04. If you have a newer version, consider using a virtual machine.

-1. Install Gazebo 11:
+1. Install Arduino CLI:
+
+   ```bash
+   curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh
+   ```
+
+2. Install Gazebo 11:

   ```bash
   curl -sSL http://get.gazebosim.org | sh
@@ -19,13 +32,19 @@ Dependencies are [Gazebo Classic simulator](https://classic.gazebosim.org) and [
   source ~/.bashrc
   ```

-2. Install SDL2:
+3. Install SDL2 and other dependencies:

   ```bash
-   sudo apt-get install libsdl2-dev
+   sudo apt-get update && sudo apt-get install build-essential libsdl2-dev
   ```

-3. Run the simulation:
+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
@@ -39,31 +58,73 @@ Dependencies are [Gazebo Classic simulator](https://classic.gazebosim.org) and [
   /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
   ```

-2. Install Gazebo 11 and SDL2:
+2. Install Arduino CLI, Gazebo 11 and SDL2:

   ```bash
   brew tap osrf/simulation
+   brew install arduino-cli
   brew install gazebo11
   brew install sdl2
   ```

+   Set up your Gazebo environment variables:
+
+   ```bash
+   echo "source /opt/homebrew/share/gazebo/setup.sh" >> ~/.zshrc
+   source ~/.zshrc
+   ```
+
 3. Run the simulation:

   ```bash
   make simulator
   ```

+### Setup and flight
+
+#### Control with smartphone
+
+1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone. For **iOS**, use [QGroundControl build from TAJISOFT](https://apps.apple.com/ru/app/qgc-from-tajisoft/id1618653051).
+2. Connect your smartphone to the same Wi-Fi network as the machine running the simulator.
+3. If you're using a virtual machine, make sure that its network is set to the **bridged** mode with Wi-Fi adapter selected.
+4. Run the simulation.
+5. Open QGroundControl app. It should connect and begin showing the virtual drone's telemetry automatically.
+6. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
+7. Use the virtual joystick to fly the drone!
+
+#### Control with USB remote control
+
+1. Connect your USB remote control to the machine running the simulator.
+2. Run the simulation.
+3. Calibrate the RC using `cr` command in the command line interface.
+4. Run the simulation again.
+5. Use the USB remote control to fly the drone!
+
 ## Firmware

 ### Arduino IDE (Windows, Linux, macOS)

-1. Install [Arduino IDE](https://www.arduino.cc/en/software).
-2. Install ESP32 core using [Boards Manager](https://docs.arduino.cc/learn/starting-guide/cores).
-3. Build and upload the firmware using Arduino IDE.
+1. Install [Arduino IDE](https://www.arduino.cc/en/software) (version 2 is recommended).
+2. Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).
+3. Install ESP32 core, version 3.1.0 (version 2.x is not supported). See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
+4. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
+   * `FlixPeriph`, the latest version.
+   * `MAVLink`, version 2.0.12.
+5. Clone the project using git or [download the source code as a ZIP archive](https://codeload.github.com/okalachev/flix/zip/refs/heads/master).
+6. Open the downloaded Arduino sketch `flix/flix.ino` in Arduino IDE.
+7. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
+8. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.

 ### Command line (Windows, Linux, macOS)

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

@@ -84,3 +145,61 @@ Dependencies are [Gazebo Classic simulator](https://classic.gazebosim.org) and [
   ```

 See other available Make commands in the [Makefile](../Makefile).
+
+> [!TIP]
+> You can test the firmware on a bare ESP32 board without connecting IMU and other peripherals. The Wi-Fi network `flix` should appear and all the basic functionality including CLI and QGroundControl connection should work.
+
+### Setup and flight
+
+Before flight you need to calibrate the accelerometer:
+
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
+2. Type `ca` command there and follow the instructions.
+
+#### Control with smartphone
+
+1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone.
+2. Power the drone using the battery.
+3. Connect your smartphone to the appeared `flix` Wi-Fi network.
+4. Open QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
+5. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
+6. Use the virtual joystick to fly the drone!
+
+#### Control with remote control
+
+Before flight using remote control, you need to calibrate it:
+
+1. Open Serial Monitor in Arduino IDE (or use `make monitor` command in the command line).
+2. Type `cr` command there and follow the instructions.
+3. Use the remote control to fly the drone!
+
+#### Control with USB remote control
+
+If your drone doesn't have RC receiver installed, you can use USB remote control and QGroundControl app to fly it.
+
+1. Install [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html) app on your computer.
+2. Connect your USB remote control to the computer.
+3. Power up the drone.
+4. Connect your computer to the appeared `flix` Wi-Fi network.
+5. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
+6. Go the the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate you USB remote control there.
+7. Use the USB remote control to fly the drone!
+
+#### Adjusting parameters
+
+You can adjust some of the drone's parameters (include PID coefficients) in QGroundControl app. In order to do that, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Parameters*.
+
+<img src="img/parameters.png" width="400">
+
+#### CLI access
+
+In addition to accessing the drone's command line interface (CLI) using the serial port, you can also access it with QGroundControl using Wi-Fi connection. To do that, go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
+
+<img src="img/cli.png" width="400">
+
+> [!NOTE]
+> If something goes wrong, go to the [Troubleshooting](troubleshooting.md) article.
+
+### Firmware code structure
+
+See [firmware overview](firmware.md) for more details.
--- a/docs/firmware.md
+++ b/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` *(double)* — current step time, *s*.
+* `dt` *(float)* — time delta between the current and previous steps, *s*.
+* `gyro` *(Vector)* — data from the gyroscope, *rad/s*.
+* `acc` *(Vector)* — acceleration data from the accelerometer, *m/s<sup>2</sup>*.
+* `rates` *(Vector)* — filtered angular rates, *rad/s*.
+* `attitude` *(Quaternion)* — estimated attitude (orientation) of drone.
+* `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).
--- a/docs/img/100n03a.jpg
+++ b/docs/img/100n03a.jpg
--- a/docs/img/assembly/1.jpg
+++ b/docs/img/assembly/1.jpg
--- a/docs/img/assembly/2.jpg
+++ b/docs/img/assembly/2.jpg
--- a/docs/img/assembly/3.jpg
+++ b/docs/img/assembly/3.jpg
--- a/docs/img/assembly/4.jpg
+++ b/docs/img/assembly/4.jpg
--- a/docs/img/assembly/5.jpg
+++ b/docs/img/assembly/5.jpg
--- a/docs/img/assembly/6.jpg
+++ b/docs/img/assembly/6.jpg
--- a/docs/img/assembly/7.jpg
+++ b/docs/img/assembly/7.jpg
--- a/docs/img/battery.jpg
+++ b/docs/img/battery.jpg
--- a/docs/img/cli.png
+++ b/docs/img/cli.png
--- a/docs/img/dataflow.svg
+++ b/docs/img/dataflow.svg
@@ -0,0 +1,330 @@
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--- a/Show More
+++ b/Show More