Change type hints of the most List arguments to Sequence in pyflix

These arguments are effectively immutable, so Sequence makes more sense - the user may use tuples in addition to lists.

.github/workflows/build.yml

@@ -10,28 +10,38 @@ on:
 jobs:
   build_linux:
     runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v4
-    - 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
     env:
         ARDUINO_SKETCH_ALWAYS_EXPORT_BINARIES: 1
+    steps:
+    - uses: actions/checkout@v7
+    - 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 for ESP32
       run: make
+    - name: Build firmware for ESP32-C3
+      run: make BOARD=esp32:esp32:esp32c3
+    - name: Build firmware for ESP32-S3
+      run: make BOARD=esp32:esp32:esp32s3:CDCOnBoot=cdc
+    - name: Build firmware for ESP32-S3 with QSPI PSRAM
+      run: make BOARD=esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=enabled EXTRA=--output-dir=flix/build/esp32.esp32.esp32s3.qspi
+    - name: Build firmware for ESP32-S3 with OPI PSRAM
+      run: make BOARD=esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=opi EXTRA=--output-dir=flix/build/esp32.esp32.esp32s3.opi
+    - name: Build firmware for Flix2
+      run: make BOARD=esp32:esp32:esp32s3:FlashSize=4M,CDCOnBoot=cdc,PSRAM=opi EXTRA='--build-property "compiler.cpp.extra_flags=-DFLIX2" --output-dir=flix/build/esp32.esp32.flix2'
     - name: Upload binaries
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: firmware-binary
         path: flix/build
-    - name: Build firmware for ESP32-S3
+    - name: Build espnow-proxy
-      run: make BOARD=esp32:esp32:esp32s3
+      run: arduino-cli compile --fqbn esp32:esp32:esp32 tools/espnow-proxy
     - name: Check c_cpp_properties.json
       run: tools/check_c_cpp_properties.py
 
   build_macos:
     runs-on: macos-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install Arduino CLI
       run: brew install arduino-cli
     - name: Build firmware
@@ -42,7 +52,7 @@ jobs:
   build_windows:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install Arduino CLI
       run: choco install arduino-cli
     - name: Install Make
@@ -62,8 +72,8 @@ jobs:
         apt-get update
         DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget build-essential cmake g++ pkg-config gnupg2 lsb-release sudo
     - name: Install Arduino CLI
-      uses: arduino/setup-arduino-cli@v1.1.1
+      run: curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=/usr/local/bin sh
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install Gazebo
       run: |
         sudo sh -c 'echo "deb http://packages.osrfoundation.org/gazebo/ubuntu-stable `lsb_release -cs` main" > /etc/apt/sources.list.d/gazebo-stable.list'
@@ -74,7 +84,16 @@ jobs:
       run: sudo apt-get install -y libsdl2-dev
     - name: Build simulator
       run: make build_simulator
-    - uses: actions/upload-artifact@v4
+    - name: Run simulator
+      env:
+        GAZEBO_MODEL_PATH: ${{ github.workspace }}/gazebo/models
+        GAZEBO_PLUGIN_PATH: ${{ github.workspace }}/gazebo/build
+      run: |
+        OUT=$(timeout -k 10s 120s gzserver --verbose gazebo/flix.world 2>&1 | tee /dev/stderr)
+        if echo "$OUT" | grep -Pq "\[Err\](?! \[RenderEngine)"; then
+          exit 1
+        fi
+    - uses: actions/upload-artifact@v7
       with:
         name: gazebo-plugin-binary
         path: gazebo/build/*.so
@@ -86,7 +105,7 @@ jobs:
     steps:
     - name: Install Arduino CLI
       run: brew install arduino-cli
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Clean up python binaries # Workaround for https://github.com/actions/setup-python/issues/577
       run: |
         rm -f /usr/local/bin/2to3*

.github/workflows/docs.yml

@@ -8,6 +8,7 @@ on:
 
 permissions:
   contents: read
+  actions: read
   pages: write
   id-token: write
 
@@ -15,7 +16,7 @@ jobs:
   markdownlint:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install markdownlint
       run: npm install -g markdownlint-cli2
     - name: Run markdownlint
@@ -24,19 +25,57 @@ jobs:
   build_book:
     runs-on: ubuntu-latest
     needs: markdownlint
+    env:
+      BINARIES: ${{ github.event_name == 'push' && (github.ref_name == 'master' || github.ref_name == 'dev') && github.repository == 'okalachev/flix' }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install mdBook
       run: cargo install mdbook --vers 0.4.43 --locked
     - name: Build book
       run: cd docs && mdbook build
+    - name: Wait for Build to complete
+      if: ${{ env.BINARIES }}
+      uses: lewagon/wait-on-check-action@v1.9.1
+      with:
+        ref: ${{ github.sha }}
+        check-name: build_linux
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        wait-interval: 30
+    - name: Find firmware binaries
+      if: ${{ env.BINARIES }}
+      id: build_run
+      run: |
+        RUN_ID=$(gh api "repos/${{ github.repository }}/actions/workflows/build.yml/runs?head_sha=${{ github.sha }}&per_page=1" --jq '.workflow_runs[0].id')
+        echo "id=$RUN_ID" >> $GITHUB_OUTPUT
+      env:
+        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    - name: Download firmware binaries
+      if: ${{ env.BINARIES }}
+      uses: actions/download-artifact@v7
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        repository: ${{ github.repository }}
+        run-id: ${{ steps.build_run.outputs.id }}
+        name: firmware-binary
+        path: docs/build
+    - name: Create shortcuts for firmware binaries
+      if: ${{ env.BINARIES }}
+      working-directory: docs/build
+      run: |
+        for FQBN in esp32.esp32.*; do
+          zip -r $FQBN.zip $FQBN
+          BOARD="${FQBN#esp32.esp32.}"
+          ln -s "$FQBN/flix.ino.merged.bin" "flix.$BOARD.merged.bin"
+          ln -s "$FQBN/flix.ino.bin" "flix.$BOARD.bin"
+          ln -s "$FQBN/flix.ino.bootloader.bin" "flix.$BOARD.bootloader.bin"
+        done
     - name: Upload artifact
-      uses: actions/upload-pages-artifact@v3
+      uses: actions/upload-pages-artifact@v5
       with:
         path: docs/build
 
   deploy:
-    if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
+    if: ${{ github.event_name == 'push' && github.ref_name == 'master' }}
     concurrency:
       group: "pages"
       cancel-in-progress: true
@@ -48,4 +87,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5

.github/workflows/tools.yml

@@ -10,7 +10,7 @@ jobs:
   csv_to_ulog:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Build csv_to_ulog
       run: cd tools/csv_to_ulog && mkdir build && cd build && cmake .. && make
     - name: Test csv_to_ulog
@@ -22,13 +22,13 @@ jobs:
   pyflix:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install Python build tools
       run: pip install build
     - name: Build pyflix
       run: python3 -m build tools
     - name: Upload artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: pyflix
         path: |
@@ -37,7 +37,7 @@ jobs:
   python_tools:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
     - name: Install Python dependencies
       run: pip install -r tools/requirements.txt
     - name: Test csv_to_mcap tool
@@ -46,3 +46,23 @@ jobs:
         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
+  sloc:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v7
+    - run: sudo apt-get install -y cloc jq
+    - name: Print source lines of code
+      run: cloc --by-file-by-lang flix
+    - name: Checkout previous revision
+      uses: actions/checkout@v7
+      with:
+        ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.base.sha || github.event.before }}
+        path: prev
+    - name: Annotate total source lines
+      run: |
+        SLOC_CURR=$(cloc flix --json | jq -r '.SUM.code')
+        SLOC_PREV=$(cloc prev/flix --json | jq -r '.SUM.code')
+        DIFF=$(printf '%+d' "$((SLOC_CURR - SLOC_PREV))")
+        echo "* Current SLOC: $SLOC_CURR" >> $GITHUB_STEP_SUMMARY
+        echo "* Previous SLOC: $SLOC_PREV" >> $GITHUB_STEP_SUMMARY
+        echo "* Diff: $DIFF" >> $GITHUB_STEP_SUMMARY

.gitignore

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

.vscode/c_cpp_properties.json

@@ -6,18 +6,18 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
-				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
 				"~/Arduino/libraries/**",
 				"/usr/include/gazebo-11/",
 				"/usr/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -33,7 +33,7 @@
 				"${workspaceFolder}/flix/parameters.ino",
 				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -53,18 +53,18 @@
 			"name": "Mac",
 			"includePath": [
 				"${workspaceFolder}/flix",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
 				"~/Documents/Arduino/libraries/**",
 				"/opt/homebrew/include/gazebo-11/",
 				"/opt/homebrew/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/flix.ino",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
@@ -80,7 +80,7 @@
 				"${workspaceFolder}/flix/parameters.ino",
 				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -103,16 +103,16 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
 				"~/Documents/Arduino/libraries/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -128,7 +128,7 @@
 				"${workspaceFolder}/flix/parameters.ino",
 				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++.exe",
+			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++.exe",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [

.vscode/extensions.json

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

Makefile

@@ -1,29 +1,40 @@
-BOARD = esp32:esp32:d1_mini32
+BOARD = esp32:esp32:esp32
-PORT := $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-*)
+PORT := $(strip $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-* /dev/cu.usbmodem*))
-PORT := $(strip $(PORT))
 
-build: .dependencies
+export ARDUINO_NETWORK_CONNECTION_TIMEOUT := 1h
-	arduino-cli compile --fqbn $(BOARD) flix
+
+build: .core .libs
+	arduino-cli compile flix --fqbn $(BOARD) --build-property "build.core_debug_level=1" $(EXTRA)
 
 upload: build
-	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" flix
+	arduino-cli upload flix --fqbn $(BOARD) -p "$(PORT)"
+
+erase:
+	arduino-cli burn-bootloader --fqbn $(BOARD) -p "$(PORT)" -P esptool
 
 monitor:
 	arduino-cli monitor -p "$(PORT)" -c baudrate=115200
 
-dependencies .dependencies:
+core .core:
-	arduino-cli core update-index --config-file arduino-cli.yaml
+	arduino-cli core update-index --additional-urls https://espressif.github.io/arduino-esp32/package_esp32_index.json
-	arduino-cli core install esp32:esp32@3.3.6 --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@3.3.10 --additional-urls https://espressif.github.io/arduino-esp32/package_esp32_index.json
+	touch .core
+
+libs .libs:
 	arduino-cli lib update-index
 	arduino-cli lib install "FlixPeriph"
 	arduino-cli lib install "MAVLink"@2.0.25
-	touch .dependencies
+	touch .libs
+
+upload_proxy: .core .libs
+	arduino-cli compile tools/espnow-proxy --fqbn $(BOARD)
+	arduino-cli upload tools/espnow-proxy --fqbn $(BOARD) -p "$(PORT)"
 
 gazebo/build cmake: gazebo/CMakeLists.txt
 	mkdir -p gazebo/build
 	cd gazebo/build && cmake ..
 
-build_simulator: .dependencies gazebo/build
+build_simulator: .libs gazebo/build
 	make -C gazebo/build
 
 simulator: build_simulator
@@ -38,6 +49,6 @@ plot:
 	plotjuggler -d $(shell ls -t tools/log/*.csv | head -n1)
 
 clean:
-	rm -rf gazebo/build flix/build flix/cache .dependencies
+	rm -rf gazebo/build flix/build flix/cache .core .libs
 
-.PHONY: build upload monitor dependencies cmake build_simulator simulator log clean
+.PHONY: build upload monitor core libs cmake build_simulator simulator log clean

README.md

@@ -21,8 +21,8 @@
 * Dedicated for education and research.
 * Made from general-purpose components.
 * Simple and clean source code in Arduino (<2k lines firmware).
-* Connectivity using Wi-Fi and MAVLink protocol.
+* Communication using MAVLink protocol over Wi-Fi or ESP-NOW.
-* Control using USB gamepad, remote control or smartphone.
+* Control with USB gamepad, remote control or smartphone.
 * Wireless command line interface and analyzing.
 * Precise simulation with Gazebo.
 * Python library for scripting and automatic flights.
@@ -47,13 +47,27 @@ See the [user builds gallery](docs/user.md):
 
 <a href="docs/user.md"><img src="docs/img/user/user.jpg" width=500></a>
 
+### PCB
+
+The official PCB *(Flix2)* is in development now. Follow the [project's channel](https://t.me/opensourcequadcopter) to track the progress.
+
+Outdoor flights demo video of the current prototype:
+
+<a href="https://youtu.be/KXlNmvUTi4g"><img width=300 src="https://i3.ytimg.com/vi/KXlNmvUTi4g/maxresdefault.jpg"></a>
+
+### Position control
+
+The position control feature is in development. RoboCamp 2026 demo (using an overhead camera, [sources](https://github.com/xTimop/flix-poscontrol/compare/robolager2026...xTimop:flix-poscontrol:poscontrol)):
+
+<a href="https://youtu.be/369Xowm4HcU"><img width=300 src="https://i3.ytimg.com/vi/369Xowm4HcU/maxresdefault.jpg"></a>
+
 ## Simulation
 
 The simulator is implemented using Gazebo and runs the original Arduino code:
 
 <img src="docs/img/simulator1.png" width=500 alt="Flix simulator">
 
-## Documentation
+## Documentation articles
 
 1. [Assembly instructions](docs/assembly.md).
 2. [Usage: build, setup and flight](docs/usage.md).
@@ -71,14 +85,14 @@ Additional articles:
 
 |Type|Part|Image|Quantity|
 |-|-|:-:|:-:|
-|Microcontroller board|ESP32 Mini|<img src="docs/img/esp32.jpg" width=100>|1|
+|Microcontroller board|ESP32 Mini.<br>ESP32-S3/ESP32-C3 boards are also supported.|<img src="docs/img/esp32.jpg" width=100>|1|
-|IMU (and barometer¹) board|GY‑91, MPU-9265 (or other MPU‑9250/MPU‑6500 board)<br>ICM20948V2 (ICM‑20948)³<br>GY-521 (MPU-6050)³⁻¹|<img src="docs/img/gy-91.jpg" width=90 align=center><br><img src="docs/img/icm-20948.jpg" width=100><br><img src="docs/img/gy-521.jpg" width=100>|1|
+|IMU (and barometer¹) board|GY‑91, MPU-9265 (or other MPU‑9250/MPU‑6500 board)<br>ICM20948V2 (ICM‑20948)<br>GY-521 (MPU-6050)|<img src="docs/img/gy-91.jpg" width=90 align=center><br><img src="docs/img/icm-20948.jpg" width=100><br><img src="docs/img/gy-521.jpg" width=100>|1|
-|Boost converter (optional, for more stable power supply)|5V output|<img src="docs/img/buck-boost.jpg" width=100>|1|
+|*Boost converter (optional, for more stable power supply)*|*5V output*|<img src="docs/img/buck-boost.jpg" width=100>|1|
 |Motor|8520 3.7V brushed motor.<br>Motor with exact 3.7V voltage is needed, not ranged working voltage (3.7V — 6V).<br>Make sure the motor shaft diameter and propeller hole diameter match!|<img src="docs/img/motor.jpeg" width=100>|4|
-|Propeller|55 mm (alternatively 65 mm)|<img src="docs/img/prop.jpg" width=100>|4|
+|Propeller|55 mm or 65 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|
+|MOSFET (transistor)|UMW 100N03A or [analog](https://t.me/opensourcequadcopter/33).<br>Warning: don't use KIA 100N03A or other manufacturers, they might not work!|<img src="docs/img/100n03a.jpg" width=100>|4|
-|Pull-down resistor|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|4|
+|Pull-down resistor<br>Voltage measurement resistor|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|6|
-|3.7V Li-Po battery|LW 952540 (or any compatible by the size)|<img src="docs/img/battery.jpg" width=100>|1|
+|3.7V Li-Po battery|LW 952540 (or any compatible by the size).<br>Make sure the battery has enough discharge rate — 25C or more!|<img src="docs/img/battery.jpg" width=100>|1|
 |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|
@@ -152,14 +166,16 @@ You can see a user-contributed [variant of complete circuit diagram](https://mir
   |-|-|
   |GND|GND|
   |VIN|VCC (or 3.3V depending on the receiver)|
-  |Signal (TX)|GPIO4¹|
+  |Signal (TX)|GPIO4|
 
-*¹ — 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.*
+* Optionally connect the battery voltage divider for voltage monitoring to any ADC1 pin (e. g. *GPIO32* on ESP32, *GPIO3* on ESP32-S3).
+
+  ESP32 and ESP32-S3 [can measure](https://docs.espressif.com/projects/arduino-esp32/en/latest/api/adc.html#analogsetattenuation) up to 3.1 V and ESP32-S3/ESP32-C3 can measure up to 2.5 V, so choose the voltage divider resistors accordingly.
 
 ## Resources
 
 * Telegram channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
-* Official Telegram chat: https://t.me/opensourcequadcopterchat.
+* Official Telegram chat: https://t.me/opensourcequadcopterchat (English / Russian).
 * Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.
 
 ## Disclaimer

arduino-cli.yaml

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

docs/assembly.md

@@ -28,6 +28,8 @@ Soldered components ([schematics variant](https://miro.com/app/board/uXjVN-dTjoo
 
 <img src="img/assembly/7.jpg" width=600>
 
+See an alternative assembly process photos here: https://drive.google.com/drive/folders/1FG5BH9RCzdf1XmJcC70PymiRMXcz6Fx7?usp=sharing.
+
 ## Motor directions
 
 > [!WARNING]

docs/firmware.md

@@ -67,6 +67,38 @@ In order to add a console command, modify the `doCommand()` function in `cli.ino
 >
 > For on-the-ground commands, use `pause()` function, instead of `delay()`. This function allows to pause in a way that MAVLink connection will continue working.
 
+### Parameter subsystem
+
+Parameters subsystem (`parameters.ino`) uses standard [Preferences.h](https://docs.espressif.com/projects/arduino-esp32/en/latest/tutorials/preferences.html) ESP32 library to store parameters in non-volatile memory. Each parameter is a regular global variable, which is registered in the `parameters` array.
+
+To add a new parameter:
+
+1. Define a global variable for the parameter, two types are supported: `float` and `int`.
+2. Add an entry to the `parameters` array, with the parameter name, a pointer to the variable, and optionally a callback function to call when the parameter is changed.
+3. Everything else will be handled automatically.
+
+See examples of adding new parameters in commits: [c434107](https://github.com/okalachev/flix/commit/c434107), [a687303](https://github.com/okalachev/flix/commit/a687303).
+
+> [!NOTE]
+> Since all the parameters are internally stored and passed as floats, the safe range for `int` parameters is -16777216 to 16777215.
+
+## Adding a subsystem
+
+To add a new subsystem:
+
+1. Create a new `*.ino` file for your subsystem.
+2. Define setup and loop functions for the subsystem, for example `setupMySubsystem()` and `loopMySubsystem()`.
+3. Use `Rate` class if you need to limit the loop frequency, for example:
+
+    ```cpp
+    Rate mySubsystemRate(100); // 100 Hz
+
+    void loopMySubsystem() {
+    	if (!mySubsystemRate) return;
+    	// Do something...
+    }
+4. Add setup and loop calls in to `setup()` and `loop()` functions in `flix.ino`.
+
 ## Building the firmware
 
 See build instructions in [usage.md](usage.md).

docs/troubleshooting.md

@@ -5,27 +5,32 @@
 Do the following:
 
 * **Check ESP32 core is installed**. Check if the version matches the one used in the [tutorial](usage.md#building-the-firmware).
-* **Check libraries**. Install all the required libraries from the tutorial. Make sure there are no MPU9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
+* **Check libraries**. Install all the required libraries from the tutorial. Make sure there are no MPU-9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
 * **Check the chosen board**. The correct board to choose in Arduino IDE for ESP32 Mini is *WEMOS D1 MINI ESP32*.
 
 ## The drone doesn't fly
 
 Do the following:
 
-* **Check the battery voltage**. Use a multimeter to measure the battery voltage. It should be in range of 3.7-4.2 V.
+* **Check the battery voltage**. Use a multimeter to measure the battery voltage. The fully charged battery should have about 4.2V.
-* **Check if there are some startup errors**. Connect the ESP32 to the computer and check the Serial Monitor output. Use the Reset button to make sure you see the whole ESP32 startup output.
+* **Check the battery you use has enough discharge current**. The battery should be able to provide 15A of current. So the C-rating for a 1000 mAh battery should be at least 15C (higher is better).
+* **Check if there are some startup errors**. Connect the ESP32 to the computer and check the Serial Monitor output. Use the Reset button or `reboot` command to see the whole startup output.
 * **Check the baudrate is correct**. If you see garbage characters in the Serial Monitor, make sure the baudrate is set to 115200.
-* **Make sure correct IMU model is chosen**. If using ICM-20948/MPU-6050 board, change `MPU9250` to `ICM20948`/`MPU6050` in the `imu.ino` file.
 * **Check if the console is working**. Perform `help` command in Serial Monitor. You should see the list of available commands. You can also access the console using QGroundControl *(Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console)*.
 * **Configure QGroundControl correctly before connecting to the drone** if you use it to control the drone. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
 * **If QGroundControl doesn't connect**, you might need to disable the firewall and/or VPN on your computer.
+* **Make sure correct IMU model is chosen**. If using ICM-20948/MPU-6050 board, change `MPU9250` to `ICM20948`/`MPU6050` in the `imu.ino` file.
 * **Check the IMU is working**. Perform `imu` command and check its output:
   * The `status` field should be `OK`.
   * The `rate` field should be about 1000 (Hz).
   * The `accel` and `gyro` fields should change as you move the drone.
-* **Calibrate the accelerometer.** if is wasn't done before. Type `ca` command in Serial Monitor and follow the instructions.
-* **Check the attitude estimation**. Connect to the drone using QGroundControl. Rotate the drone in different orientations and check if the attitude estimation shown in QGroundControl is correct.
 * **Check the IMU orientation is set correctly**. If the attitude estimation is rotated, set the correct IMU orientation as described in the [tutorial](usage.md#define-imu-orientation).
+* **Calibrate the accelerometer.** if is wasn't done before. Type `ca` command in Serial Monitor and follow the instructions.
+* **Check the attitude estimation**. Connect to the drone using QGroundControl. Rotate the drone in different orientations and check if the attitude estimation is shown exactly as on the video below:
+
+  <a href="https://youtu.be/yVRN23-GISU"><img width=200 src="https://i3.ytimg.com/vi/yVRN23-GISU/maxresdefault.jpg"></a>
+
+* **Check the IMU output**. Connect to the drone using QGroundControl on your computer. Go to the *Analyze* tab, *MAVLINK Inspector*. Plot the data from the `SCALED_IMU` message. The gyroscope and accelerometer data should change according to the drone movement.
 * **Check the motors type**. Motors with exact 3.7V voltage are needed, not ranged working voltage (3.7V — 6V).
 * **Check the motors**. Perform the following commands using Serial Monitor:
   * `mfr` — should rotate front right motor (counter-clockwise).
@@ -33,7 +38,10 @@ Do the following:
   * `mrl` — should rotate rear left motor (counter-clockwise).
   * `mrr` — should rotate rear right motor (clockwise).
 * **Check the propeller directions are correct**. Make sure your propeller types (A or B) are installed as on the picture:
+
   <img src="img/user/peter_ukhov-2/1.jpg" width="200">
-* **Check the remote control**. Using `rc` command, check the control values reflect your sticks movement. All the controls should change between -1 and 1, and throttle between 0 and 1.
+
-* If using SBUS receiver, **calibrate the RC**. Type `cr` command in Serial Monitor and follow the instructions.
+* **If using an SBUS receiver**:
-* **Check the IMU output using QGroundControl**. Connect to the drone using QGroundControl on your computer. Go to the *Analyze* tab, *MAVLINK Inspector*. Plot the data from the `SCALED_IMU` message. The gyroscope and accelerometer data should change according to the drone movement.
+  * **Define the used GPIO pin** in `RC_RX_PIN` parameter.
+  * **Calibrate the RC** using `cr` command in the console.
+  * **Check the controls** using `rc` command. All the controls should change between -1 and 1, and the throttle between 0 and 1.

docs/usage.md

@@ -1,34 +1,63 @@
 # Usage: build, setup and flight
 
-To fly Flix quadcopter, you need to build the firmware, upload it to the ESP32 board, and set up the drone for flight.
+To fly Flix quadcopter, you need to upload the firmware to the ESP32 board, and set up the drone for flight.
 
-To get the firmware sources, clone the repository using git:
+## Uploading the firmware
+
+You can either use the **prebuilt binaries** or **build the firmware** from sources — this will let you modify the firmware and add new features.
+
+### Prebuilt binaries (the easiest way)
+
+1. Download the latest firmware file using the following links:
+
+   <!-- markdownlint-disable MD044 -->
+   |Type|Boards|Link|
+   |-|-|-|
+   |ESP32|DevKit, D1 Mini|[`quadcopter.dev/flix.esp32.merged.bin`](https://quadcopter.dev/flix.esp32.merged.bin)|
+   |ESP32-S3|Most S3 based|[`quadcopter.dev/flix.esp32s3.merged.bin`](https://quadcopter.dev/flix.esp32s3.merged.bin)|
+   |ESP32-S3 (2MB PSRAM)|S3 Super Mini, S3 Zero (2MB PSRAM)|[`quadcopter.dev/flix.esp32s3.qspi.merged.bin`](https://quadcopter.dev/flix.esp32s3.qspi.merged.bin)|
+   |ESP32-S3 (8/16MB PSRAM)|S3 Zero (8MB PSRAM)|[`quadcopter.dev/flix.esp32s3.opi.merged.bin`](https://quadcopter.dev/flix.esp32s3.opi.merged.bin)|
+   |ESP32-C3|C3 Super Mini|[`quadcopter.dev/flix.esp32c3.merged.bin`](https://quadcopter.dev/flix.esp32c3.merged.bin)|
+   |Flix2|Flix2 board|[`quadcopter.dev/flix.flix2.merged.bin`](https://quadcopter.dev/flix.flix2.merged.bin)|
+   <!-- markdownlint-enable MD044 -->
+
+2. Flash your ESP32 board using [ESP32 Web Flasher](https://www.espboards.dev/tools/program/):
+
+   <img src="img/web-flasher.png" width="400">
+
+   * Connect the board to your computer, press *Connect to ESP*, choose the serial port.
+   * Go to the *Flash* tab.
+   * Choose the downloaded firmware file, set *Flash address* to *0* (important).
+   * Click *Program* button and wait until the process is finished.
+
+### Building from sources (flexible)
+
+You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
+
+Get the sources using git:
 
 ```bash
 git clone https://github.com/okalachev/flix.git && cd flix
 ```
 
-Beginners can [download the source code as a ZIP archive](https://github.com/okalachev/flix/archive/refs/heads/master.zip).
+Beginners can [download the sources as a ZIP archive](https://github.com/okalachev/flix/archive/refs/heads/master.zip).
 
-## Building the firmware
+#### Arduino IDE (Windows, Linux, macOS)
-
-You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
-
-### Arduino IDE (Windows, Linux, macOS)
 
 <img src="img/arduino-ide.png" width="400" alt="Flix firmware open in Arduino IDE">
 
 1. Install [Arduino IDE](https://www.arduino.cc/en/software) (version 2 is recommended).
 2. *Windows users might need to install [USB to UART bridge driver from Silicon Labs](https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers).*
-3. Install ESP32 core, version 3.3.6. See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
+3. Install ESP32 core, version 3.3.10. See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
 4. Install the following libraries using [Library Manager](https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-installing-a-library):
    * `FlixPeriph`, the latest version.
    * `MAVLink`, version 2.0.25.
 5. Open the `flix/flix.ino` sketch from downloaded firmware sources in Arduino IDE.
-6. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
+6. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini, *ESP32S3 Dev Module* for ESP32-S3 Super Mini) and the port.
-7. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
+7. Set *Tools* ⇒ *Core Debug Level* to *Error* to see the errors in the serial console. Set *Tools* ⇒ *USB CDC on Boot* to *Enabled* for ESP32-S3/ESP32-C3 boards.
+8. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
 
-### Command line (Windows, Linux, macOS)
+#### Command line (Windows, Linux, macOS)
 
 1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
 
@@ -57,6 +86,12 @@ You can build and upload the firmware using either **Arduino IDE** (easier for b
    make upload monitor
    ```
 
+   For ESP32-S3/ESP32-C3 boards, set the appropriate [FQBN](https://docs.arduino.cc/arduino-cli/FAQ/#whats-the-fqbn-string) using `BOARD` parameter:
+
+   ```bash
+   make BOARD=esp32:esp32:esp32s3:FlashSize=4M,CDCOnBoot=cdc upload
+   ```
+
 See other available Make commands in [Makefile](../Makefile).
 
 > [!TIP]
@@ -64,15 +99,6 @@ See other available Make commands in [Makefile](../Makefile).
 
 ## Before first flight
 
-### Choose the IMU model
-
-In case if using different IMU model than MPU9250, change `imu` variable declaration in the `imu.ino`:
-
-```cpp
-ICM20948 imu(SPI);  // For ICM-20948
-MPU6050 imu(Wire);  // For MPU-6050
-```
-
 ### Connect using QGroundControl
 
 QGroundControl is a ground control station software that can be used to monitor and control the drone.
@@ -82,6 +108,9 @@ QGroundControl is a ground control station software that can be used to monitor
 3. Connect your computer or smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
 4. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
 
+> [!TIP]
+> If QGroundControl doesn't connect, try to disable the firewall and/or VPN on your computer, as they may block the connection.
+
 ### Access console
 
 The console is a command line interface (CLI) that allows to interact with the drone, change parameters, and perform various actions. There are two ways of accessing the console: using **serial port** or using **QGroundControl (wirelessly)**.
@@ -95,7 +124,7 @@ To access the console using serial port:
 To access the console using QGroundControl:
 
 1. Connect to the drone using QGroundControl app.
-2. Go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
+2. Go to the QGroundControl menu ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
 
 <img src="img/cli.png" width="400">
 
@@ -110,11 +139,22 @@ The drone is configured using parameters. To access and modify them, go to the Q
 
 You can also work with parameters using `p` command in the console. Parameter names are case-insensitive.
 
+### Configure the IMU
+
+1. Configure the following parameters for the IMU:
+   * `IMU_MODEL` — IMU model (1 for MPU-9250/MPU-6500, 2 for ICM-20948, 3 for MPU-6050, 4 for ICM-40609-D).
+   * `IMU_BUS` — communication bus (0 for SPI, 1 for I²C).
+   * `IMU_PIN_SCK`, `IMU_PIN_MISO`, `IMU_PIN_MOSI`, `IMU_PIN_CS` — SPI pin numbers.
+   * `IMU_PIN_SCL`, `IMU_PIN_SDA` — I²C pin numbers.
+   * `IMU_PIN_INT` — IMU data ready pin number (-1 if not used).
+2. Reboot the drone.
+3. Check the IMU is working using `imu` command in the console (should print `status: OK`).
+
 ### Define IMU orientation
 
-Use parameters, to define the IMU board axes orientation relative to the drone's axes: `IMU_ROT_ROLL`, `IMU_ROT_PITCH`, and `IMU_ROT_YAW`.
+The IMU orientation (relative to the drone's axes) is defined using the parameters: `IMU_ROT_ROLL`, `IMU_ROT_PITCH`, and `IMU_ROT_YAW`.
 
-The drone has *X* axis pointing forward, *Y* axis pointing left, and *Z* axis pointing up, and the supported IMU boards have *X* axis pointing to the pins side and *Z* axis pointing up from the component side:
+The drone has *X* axis pointing forward, *Y* axis pointing left, and *Z* axis pointing up, and the supported IMU boards have *X* axis pointing to the mounting holes side and *Z* axis pointing up from the component side:
 
 <img src="img/imu-axes.png" width="200">
 
@@ -122,10 +162,10 @@ Use the following table to set the parameters for common IMU orientations:
 
 |Orientation|Parameters|Orientation|Parameters|
 |:-:|-|-|-|
-|<img src="img/imu-rot-1.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0    |<img src="img/imu-rot-5.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0|
+|<img src="img/imu-rot-3.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0    |<img src="img/imu-rot-7.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0|
-|<img src="img/imu-rot-2.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|<img src="img/imu-rot-6.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|
+|<img src="img/imu-rot-2.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|<img src="img/imu-rot-6.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|
-|<img src="img/imu-rot-3.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|<img src="img/imu-rot-7.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|
+|<img src="img/imu-rot-1.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|<img src="img/imu-rot-5.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|
-|<img src="img/imu-rot-4.png" width="180"><br>☑️ **Default**|<br>`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|<img src="img/imu-rot-8.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|
+|<img src="img/imu-rot-4.png" width="180"><br>☑️ **Default**|<br>`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|<img src="img/imu-rot-8.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|
 
 ### Calibrate accelerometer
 
@@ -138,37 +178,48 @@ Before flight you need to calibrate the accelerometer:
 
 If using non-default motor pins, set the pin numbers using the parameters: `MOTOR_PIN_FL`, `MOTOR_PIN_FR`, `MOTOR_PIN_RL`, `MOTOR_PIN_RR` (front-left, front-right, rear-left, rear-right respectively).
 
-If using brushless motors and ESCs:
+#### Brushless motors
+
+If using brushless motors with ESCs:
 
 1. Set the appropriate PWM using the parameters: `MOT_PWM_STOP`, `MOT_PWM_MIN`, and `MOT_PWM_MAX` (1000, 1000, and 2000 is typical).
 2. Decrease the PWM frequency using the `MOT_PWM_FREQ` parameter (400 is typical).
 
-Reboot the drone to apply the changes.
-
 > [!CAUTION]
 > **Remove the props when configuring the motors!** If improperly configured, you may not be able to stop them.
 
-### Check everything works
+### Battery voltage monitoring (optional)
 
-1. Check the IMU is working: perform `imu` command and check its output:
+ESP32 ADC can measure only up to 3.3 V, so you need to use a voltage divider to monitor the battery voltage. To enable voltage measurement, set the following parameters:
+
+1. `PWR_VOLT_PIN` — GPIO pin number where the voltage divider is connected (*-1* to disable).
+2. `PWR_VOLT_SCALE` — voltage divider coefficient (*2* for two equal resistors).
+
+After this setup, you should see the battery voltage in QGroundControl top panel or using `pw` command in the console.
+
+### Important: check everything works
+
+1. Check the IMU is working: perform `imu` command in the console and check the output:
 
    * The `status` field should be `OK`.
    * The `rate` field should be about 1000 (Hz).
    * The `accel` and `gyro` fields should change as you move the drone.
+   * The `accel bias` and `accel scale` fields should contain calibration parameters (not zeros and ones).
+   * The `gyro bias` field should contain estimated gyro bias (not zeros).
    * The `landed` field should be `1` when the drone is still on the ground and `0` when you lift it up.
 
 2. Check the attitude estimation: connect to the drone using QGroundControl, rotate the drone in different orientations and check if the attitude estimation shown in QGroundControl is correct. Compare your attitude indicator (in the *large vertical* mode) to the video:
 
    <a href="https://youtu.be/yVRN23-GISU"><img width=300 src="https://i3.ytimg.com/vi/yVRN23-GISU/maxresdefault.jpg"></a>
 
-3. Perform motor tests in the console. Use the following commands **— remove the propellers before running the tests!**
+3. Perform motor tests. Use the following commands **— remove the propellers before running the tests!**
 
-   * `mfr` — should rotate front right motor (counter-clockwise).
+   * `mfr` — rotate front right motor (counter-clockwise).
-   * `mfl` — should rotate front left motor (clockwise).
+   * `mfl` — rotate front left motor (clockwise).
-   * `mrl` — should rotate rear left motor (counter-clockwise).
+   * `mrl` — rotate rear left motor (counter-clockwise).
-   * `mrr` — should rotate rear right motor (clockwise).
+   * `mrr` — rotate rear right motor (clockwise).
 
-   Rotation diagram:
+   Make sure rotation directions and propeller types match the following diagram:
 
    <img src="img/motors.svg" width=200>
 
@@ -177,10 +228,22 @@ Reboot the drone to apply the changes.
 
 ## Setup remote control
 
-There are several ways to control the drone's flight: using **smartphone** (Wi-Fi), using **SBUS remote control**, or using **USB remote control** (Wi-Fi).
+There are several ways to control the drone's flight: using **smartphone** (Wi-Fi), using **SBUS remote control**, or using **USB remote control** (Wi-Fi/ESP-NOW).
 
 ### Control with a smartphone
 
+#### Using Mavlink Joystick app (Android)
+
+<img src="https://github.com/goldarte/mavlink-joystick/blob/master/app_screen.png?raw=true" width="400">
+
+1. Download and install [Mavlink Joystick app](https://github.com/goldarte/mavlink-joystick/releases/latest).
+2. Power the drone using the battery.
+3. Connect your smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
+4. Open Mavlink Joystick app. It should connect and begin showing the drone's telemetry automatically.
+5. Use the virtual joystick to fly the drone!
+
+#### Using QGroundControl app
+
 1. Install [QGroundControl mobile app](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html#android) on your smartphone.
 2. Power the drone using the battery.
 3. Connect your smartphone to the appeared `flix` Wi-Fi network (password: `flixwifi`).
@@ -193,11 +256,13 @@ There are several ways to control the drone's flight: using **smartphone** (Wi-F
 
 ### Control with a remote control
 
-Before using remote SBUS-connected remote control, you need to calibrate it:
+If using SBUS-connected remote control you need to enable SBUS and calibrate it:
 
-1. Access the console using QGroundControl (recommended) or Serial Monitor.
+1. Connect to the drone using QGroundControl.
-2. Type `cr` command and follow the instructions.
+2. In parameters, set the `RC_RX_PIN` parameter to the GPIO pin number where the SBUS signal is connected, for example: 4. Negative value disables SBUS.
-3. Use the remote control to fly the drone!
+3. Check if the receiver is working using `rc` command in the console.
+4. Open the console, type `cr` command and follow the instructions to calibrate the remote control.
+5. Use the remote control to fly the drone!
 
 ### Control with a USB remote control
 
@@ -208,7 +273,7 @@ If your drone doesn't have RC receiver installed, you can use USB remote control
 3. Power up the drone.
 4. Connect your computer to the appeared `flix` Wi-Fi network (password: `flixwifi`).
 5. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically.
-6. Go the the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate you USB remote control there.
+6. Go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Joystick*. Calibrate your USB remote control there.
 7. Use the USB remote control to fly the drone!
 
 ## Flight
@@ -234,11 +299,11 @@ When finished flying, **disarm** the drone, moving the left stick to the bottom
 
 ### Flight modes
 
-Flight mode is changed using mode switch on the remote control or using the command line.
+Flight mode is changed using mode switch on the remote control (if configured) or using the console commands. The main flight mode is *STAB*. In order to change modes using SBUS remote control, set the parameters: `CTL_FLT_MODE_0`, `CTL_FLT_MODE_1`, and `CTL_FLT_MODE_2` to required mode numbers (0 for *RAW*, 1 for *ACRO*, 2 for *STAB*, 3 for *AUTO*).
 
 #### STAB
 
-The default mode is *STAB*. In this mode, the drone stabilizes its attitude (orientation). The left stick controls throttle and yaw rate, the right stick controls pitch and roll angles.
+In this mode, the drone stabilizes its attitude (orientation). The left stick controls throttle and yaw rate, the right stick controls pitch and roll angles.
 
 > [!IMPORTANT]
 > The drone doesn't stabilize its position, so slight drift is possible. The pilot should compensate it manually.
@@ -253,9 +318,9 @@ In this mode, the pilot controls the angular rates. This control method is diffi
 
 #### AUTO
 
-In this mode, the pilot inputs are ignored (except the mode switch, if configured). The drone can be controlled using [pyflix](../tools/pyflix/) Python library, or by modifying the firmware to implement the needed autonomous behavior.
+In this mode, the pilot inputs are ignored (except the mode switch). The drone can be controlled using [pyflix](../tools/pyflix/) Python library, or by modifying the firmware to implement the needed behavior.
 
-If the pilot moves the control sticks, the drone will switch back to *STAB* mode.
+If the pilot moves the control sticks and mode switch is not configured, the drone will switch back to *STAB* mode.
 
 ## Wi-Fi configuration
 
@@ -265,11 +330,8 @@ The Wi-Fi mode is chosen using `WIFI_MODE` parameter in QGroundControl or in the
 
 * `0` — Wi-Fi is disabled.
 * `1` — Access Point mode *(AP)* — the drone creates a Wi-Fi network.
-* `2` — Client mode *(STA)* — the drone connects to an existing Wi-Fi network.
+* `2` — Client mode *(STA)* — the drone connects to an existing Wi-Fi network (may cause additional delays, so generally not recommended).
-* `3` — *ESP-NOW (not implemented yet)*.
+* `3` — ESP-NOW mode — the drone uses ESP-NOW protocol for communication.
-
-> [!WARNING]
-> Tests showed that Client mode may cause **additional delays** in remote control (due to retranslations), so it's generally not recommended.
 
 The SSID and password are configured using the `ap` and `sta` console commands:
 
@@ -291,9 +353,43 @@ Disabling Wi-Fi:
 p WIFI_MODE 0
 ```
 
+### Using ESP-NOW
+
+[ESP-NOW](https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/network/esp_now.html) is a low level wireless communication protocol. It can provide lower latency, better reliability, and longer range than Wi-Fi. However, it requires a second ESP32 board to be used as a proxy for the computer.
+
+<img src="img/espnow-connection.jpg" width="600">
+
+To setup ESP-NOW communication:
+
+1. Flash the second ESP32 board with ESP-NOW proxy sketch: [`tools/espnow-proxy/espnow-proxy.ino`](../tools/espnow-proxy/espnow-proxy.ino). Use Arduino IDE or command line: `make upload_proxy`.
+
+2. Open Serial Monitor in Arduino IDE or use `make monitor` command. The ESP32 will print its MAC address and generated encryption key, for example:
+
+   ```
+   espnow 7a:c8:e3:eb:bf:e9 &PiuSysxP9+$L&5E
+   ```
+
+   Run this line as a console command on each drone you want to bind to this proxy board. [The maximum number](https://github.com/espressif/esp-idf/blob/e95cab4be8fd293e3f3323181e7a2280874da6f7/components/esp_wifi/include/esp_now.h#L32-L33) of simultaneously connected drones is 20 (unencrypted) or 6 (encrypted).
+
+3. Set the `WIFI_MODE` parameter to `3` on the drone:
+
+   ```
+   p WIFI_MODE 3
+   ```
+
+4. Go to the QGroundControl menu ⇒ *Application Settings* ⇒ *Comm Links*, add new link with the following settings:
+   * Name: ESP32.
+   * Type: Serial.
+   * Serial Port: choose the port of the proxy ESP32 board, e. g. `/dev/cu.usbserial-0001`.
+   * Baud Rate: 115200.
+5. Click *Save*, click *Connect*. QGroundControl should connect to the drone using ESP-NOW and begin showing the telemetry.
+
+> [!TIP]
+> Make sure Arduino IDE is not running when using ESP-NOW proxy board, as it may block the serial port.
+
 ## Flight log
 
-After the flight, you can download the flight log for analysis wirelessly. Use the following command on your computer for that:
+After the flight, you can download the flight log wirelessly for analysis. Use the following command on your computer for that:
 
 ```bash
 make log

docs/user.md

@@ -4,6 +4,98 @@ This page contains user-built drones based on the Flix project. Publish your pro
 
 ---
 
+Author: [Oleg1405](https://t.me/Oleg1405).<br>
+Description: ESP32 Mini, MPU-6500 IMU, boost converter, BT2.0 power connector, 65 mm props, BetaFPV ELRS Lite Receiver, Radiomaster Pocket + Mavlink Joystick (Android) control.
+
+<img src="img/user/oleg1405/1.jpg" height=300>
+
+[Flight video](https://www.youtube.com/shorts/rbXV4sHbpso).
+
+---
+
+Author: Alican Erüst.<br>
+Description: QX95 mm frame, 55 mm propellers, 3.7 V 25C 1050 mAh LiPo battery, MPU6050 IMU, Logitech F310 gamepad controller, with a total quadcopter weight of 66 g.
+
+<img src="img/user/alicanerus/1.jpg" height=200> <img src="img/user/alicanerus/2.jpg" height=200> <img src="img/user/alicanerus/3.jpg" height=200>
+
+[Flight video](https://drive.google.com/file/d/1k0WeWTKnCAfaugkX7LcmNxsUuq79RL8Z/view?usp=sharing).
+
+---
+
+Author: [Неруш Михаил](https://t.me/NerushMV).<br>
+Description: custom frame made of 4 mm plywood, 8520 brushed motors, 75 mm propellers, MPU-6500. FlySky FS-i6X with ESP32-based adapter for ESP-NOW communication (using PPM output).<br>
+Sources and materials: [link](https://drive.google.com/drive/folders/1uWiDcuorLrtVs_IIR7Y13omij-7Q1nx8).
+
+<img src="img/user/nerush/1.jpg" height=200> <img src="img/user/nerush/2.jpg" height=200>
+
+[Flight video](https://drive.google.com/file/d/1jRXeGx34lJpUfw0GKLQeIzkWZvooQJSE/view?usp=sharing).
+
+---
+
+Author: [Konstantinos Paraskevas](https://github.com/Frapais).<br>
+Description: drone with a custom single-boarded airframe, extending the [Sprig-C3 module](https://github.com/Frapais/Sprig-C3).
+ESP32-C3 microcontroller, ICM-20948 IMU, on-board fuel-gauge, status LED indicator.<br>
+Repository with all the code and PCB sources: https://github.com/Frapais/Sprig-Drone.
+
+<img src="img/user/kostas/1.jpg" height=150> <img src="img/user/kostas/2.jpg" height=150>
+
+Detailed video about making the drone:
+
+<a href="https://youtu.be/82Q-uBq6s48"><img width=400 src="https://i3.ytimg.com/vi/82Q-uBq6s48/maxresdefault.jpg"></a>
+
+---
+
+Author: [Awab Anas](http://t.me/AW_VENOM).<br>
+Description: ESP32 D1 Mini, MPU-6050, 8520 3.7V brushed motors, 55 mm propellers, battery li-po 1200 mAh, controlling via [Mavlink Joystick app](https://github.com/goldarte/mavlink-joystick/releases/latest).<br>
+[Flight validation](https://drive.google.com/file/d/12z0jfctZDBA6b5UKCG0Uje5rAxj6DhF-/view?usp=sharing).
+
+<img src="img/user/aw_venom/1.jpg" height=200>
+
+---
+
+Author: [Ina Tix](https://t.me/ina_tix).<br>
+Description: XR2981 based DC-DC converter, ELRS MINI 2.4GHz RX SX1280 receiver (SBUS interface), Radiomaster TX12 remote control.<br>
+[Flight validation](https://drive.google.com/file/d/1yqkKNuz4R_yxGqUNQxVpixJbXqEEcUSj/view?usp=share_link).
+
+<img src="img/user/ina_tix/1.jpg" height=200> <img src="img/user/ina_tix/2.jpg" height=200> <img src="img/user/ina_tix/3.jpg" height=200>
+
+---
+
+Author: Oleg Kalachev.<br>
+Description: the first attempt on making an official PCB based Flix drone (Flix2 board). The IMU is not working on this version, so an external MPU-6050 board was used, therefore considered as **Flix version 1.5**.<br>
+[Flight video](https://drive.google.com/file/d/1R7tuUsFmPY0CGcOCFfMFaCp9kR49K3bl/view?usp=sharing).
+
+<img src="img/flix1.5.jpg" width=300>
+
+---
+
+Author: [FanBy0ru](https://https://github.com/FanBy0ru).<br>
+Description: custom 3D-printed frame.<br>
+Frame STLs and flight validation: https://cults3d.com/en/3d-model/gadget/armature-pour-flix-drone.
+
+<img src="img/user/fanby0ru/1.jpg" height=200> <img src="img/user/fanby0ru/2.jpg" height=200>
+
+---
+
+Author: Ivan44 Phalko.<br>
+Description: custom PCB, cusom test bench.<br>
+[Flight validation](https://drive.google.com/file/d/17DNDJ1gPmCmDRAwjedCbJ9RXAyqMqqcX/view?usp=sharing).
+
+<img src="img/user/phalko/1.jpg" height=200> <img src="img/user/phalko/2.jpg" height=200> <img src="img/user/phalko/3.jpg" height=200>
+
+---
+
+Author: **Arkadiy "Arky" Matsekh**, Foucault Dynamics, Gold Coast, Australia.<br>
+The drone was built for the University of Queensland industry-led Master's capstone project.
+
+**Flight video:**
+
+<a href="https://drive.google.com/file/d/1NNYSVXBY-w0JjCo07D8-PgnVq3ca9plj/view?usp=sharing"><img height=300 src="img/user/arkymatsekh/video.jpg"></a>
+
+<img src="img/user/arkymatsekh/1.jpg" height=150> <img src="img/user/arkymatsekh/2.jpg" height=150> <img src="img/user/arkymatsekh/3.jpg" height=150>
+
+---
+
 Author: [goldarte](https://t.me/goldarte).<br>
 
 <img src="img/user/goldarte/1.jpg" height=150> <img src="img/user/goldarte/2.jpg" height=150>
@@ -14,6 +106,17 @@ Author: [goldarte](https://t.me/goldarte).<br>
 
 ---
 
+Author: [malagis](https://oshwhub.com/malagis).<br>
+
+A Chinese custom PCB version of Flix with a big community of users, lots of materials and modifications.
+
+Main project's page: https://oshwhub.com/malagis/esp32-mini-plane.<br>
+Video about the project: https://www.bilibili.com/video/BV14vyqBFEJn/.
+
+<img src="img/user/malagis/1.jpg" height=200> <img src="img/user/malagis/2.jpg" height=200> <img src="img/user/malagis/3.jpg" height=200>
+
+---
+
 ## School 548 course
 
 Special course on quadcopter design and engineering took place in october-november 2025 in School 548, Moscow. The course included UAV control theory, electronics, drone assembly and setup practice, using the Flix project.

flix/cli.ino

@@ -6,53 +6,58 @@
 #include "pid.h"
 #include "vector.h"
 #include "util.h"
-#include "lpf.h"
+#include "filter.h"
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
 extern const int RAW, ACRO, STAB, AUTO;
+extern const int W_AP, W_STA, W_ESPNOW;
 extern float t, dt, loopRate;
 extern uint16_t channels[16];
 extern float controlTime;
 extern int mode;
 extern bool armed;
 extern LowPassFilter<Vector> gyroBiasFilter;
+extern float voltage;
 
 const char* motd =
-"\nWelcome to\n"
 " _______  __       __  ___   ___\n"
 "|   ____||  |     |  | \\  \\ /  /\n"
 "|  |__   |  |     |  |  \\  V  /\n"
 "|   __|  |  |     |  |   >   <\n"
 "|  |     |  `----.|  |  /  .  \\\n"
 "|__|     |_______||__| /__/ \\__\\\n\n"
+"(C) Oleg Kalachev\n"
+"https://github.com/okalachev/flix\n\n"
 "Commands:\n\n"
 "help - show help\n"
 "p - show all parameters\n"
-"p <name> - show parameter\n"
+"p <str> - show parameters starting with str\n"
 "p <name> <value> - set parameter\n"
 "preset - reset parameters\n"
 "time - show time info\n"
-"ps - show pitch/roll/yaw\n"
-"psq - show attitude quaternion\n"
 "imu - show IMU data\n"
+"ca - calibrate accel\n"
+"st - show state estimation\n"
 "arm - arm the drone\n"
 "disarm - disarm the drone\n"
 "raw/stab/acro/auto - set mode\n"
 "rc - show RC data\n"
+"cr - calibrate RC\n"
+"pw - show power info\n"
 "wifi - show Wi-Fi info\n"
-"ap <ssid> <password> - setup Wi-Fi access point\n"
+"wifi ap/sta/espnow/off - set Wi-Fi mode\n"
-"sta <ssid> <password> - setup Wi-Fi client mode\n"
+"ap <ssid> <password> - configure Wi-Fi access point\n"
+"sta <ssid> <password> - configure Wi-Fi client mode\n"
+"espnow <mac> [<key>] - configure ESP-NOW peer\n"
 "mot - show motor output\n"
 "log [dump] - print log header [and data]\n"
-"cr - calibrate RC\n"
+"mfr/mfl/mrr/mrl [<thrust>] - test motor (remove props)\n"
-"ca - calibrate accel\n"
-"mfr, mfl, mrr, mrl - test motor (remove props)\n"
 "sys - show system info\n"
 "reset - reset drone's state\n"
 "reboot - reboot the drone\n";
 
 void print(const char* format, ...) {
-	char buf[1000];
+	char buf[3000];
 	va_list args;
 	va_start(args, format);
 	vsnprintf(buf, sizeof(buf), format, args);
@@ -87,14 +92,12 @@ void doCommand(String str, bool echo = false) {
 	// execute command
 	if (command == "help" || command == "motd") {
 		print("%s\n", motd);
-	} else if (command == "p" && arg0 == "") {
+	} else if (command == "p" && arg1 == "") {
-		printParameters();
+		printParameters(arg0.c_str());
-	} else if (command == "p" && arg0 != "" && arg1 == "") {
-		print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
 	} else if (command == "p") {
 		bool success = setParameter(arg0.c_str(), arg1.toFloat());
 		if (success) {
-			print("%s = %g\n", arg0.c_str(), arg1.toFloat());
+			print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
 		} else {
 			print("Parameter not found: %s\n", arg0.c_str());
 		}
@@ -104,15 +107,15 @@ void doCommand(String str, bool echo = false) {
 		print("Time: %f\n", t);
 		print("Loop rate: %.0f\n", loopRate);
 		print("dt: %f\n", dt);
-	} else if (command == "ps") {
-		Vector a = attitude.toEuler();
-		print("roll: %f pitch: %f yaw: %f\n", degrees(a.x), degrees(a.y), degrees(a.z));
-	} else if (command == "psq") {
-		print("qw: %f qx: %f qy: %f qz: %f\n", attitude.w, attitude.x, attitude.y, attitude.z);
 	} else if (command == "imu") {
 		printIMUInfo();
 		printIMUCalibration();
 		print("landed: %d\n", landed);
+	} else if (command == "st") {
+		print("rates: %g %g %g\n", rates.x, rates.y, rates.z);
+		print("attitude: %g %g %g %g\n", attitude.w, attitude.x, attitude.y, attitude.z);
+		print("roll: %g° pitch: %g° yaw: %g°\n", degrees(attitude.getRoll()), degrees(attitude.getPitch()), degrees(attitude.getYaw()));
+		print("landed: %d\n", landed);
 	} else if (command == "arm") {
 		armed = true;
 	} else if (command == "disarm") {
@@ -135,12 +138,18 @@ void doCommand(String str, bool echo = false) {
 		print("time: %.1f\n", controlTime);
 		print("mode: %s\n", getModeName());
 		print("armed: %d\n", armed);
-	} else if (command == "wifi") {
+	} else if (command == "pw") {
+		print("Voltage: %.1f V\n", voltage);
+	} else if (command == "wifi" && arg0 == "") {
 		printWiFiInfo();
+	} else if (command == "wifi") {
+		setWiFiMode(arg0);
 	} else if (command == "ap") {
-		configWiFi(true, arg0.c_str(), arg1.c_str());
+		configWiFi(W_AP, arg0.c_str(), arg1.c_str());
 	} else if (command == "sta") {
-		configWiFi(false, arg0.c_str(), arg1.c_str());
+		configWiFi(W_STA, arg0.c_str(), arg1.c_str());
+	} else if (command == "espnow") {
+		configWiFi(W_ESPNOW, arg0.c_str(), arg1.c_str());
 	} else if (command == "mot") {
 		print("front-right %g front-left %g rear-right %g rear-left %g\n",
 			motors[MOTOR_FRONT_RIGHT], motors[MOTOR_FRONT_LEFT], motors[MOTOR_REAR_RIGHT], motors[MOTOR_REAR_LEFT]);
@@ -152,20 +161,22 @@ void doCommand(String str, bool echo = false) {
 	} else if (command == "ca") {
 		calibrateAccel();
 	} else if (command == "mfr") {
-		testMotor(MOTOR_FRONT_RIGHT);
+		testMotor(MOTOR_FRONT_RIGHT, arg0.isEmpty() ? 0.2 : arg0.toFloat());
 	} else if (command == "mfl") {
-		testMotor(MOTOR_FRONT_LEFT);
+		testMotor(MOTOR_FRONT_LEFT, arg0.isEmpty() ? 0.2 : arg0.toFloat());
 	} else if (command == "mrr") {
-		testMotor(MOTOR_REAR_RIGHT);
+		testMotor(MOTOR_REAR_RIGHT, arg0.isEmpty() ? 0.2 : arg0.toFloat());
 	} else if (command == "mrl") {
-		testMotor(MOTOR_REAR_LEFT);
+		testMotor(MOTOR_REAR_LEFT, arg0.isEmpty() ? 0.2 : arg0.toFloat());
 	} else if (command == "sys") {
 #ifdef ESP32
 		print("Chip: %s\n", ESP.getChipModel());
 		print("Temperature: %.1f °C\n", temperatureRead());
-		print("Free heap: %d\n", ESP.getFreeHeap());
+		print("Total RAM: %d KB\n", ESP.getHeapSize() / 1024);
+		print("Free heap: %d KB\n", ESP.getFreeHeap() / 1024);
+		print("Firmware: " __DATE__ " " __TIME__ "\n");
 		// Print tasks table
-		print("Num  Task                Stack  Prio  Core  CPU%%\n");
+		print("Num  Task                MinSt  Prio  Core  CPU%%\n");
 		int taskCount = uxTaskGetNumberOfTasks();
 		TaskStatus_t *systemState = new TaskStatus_t[taskCount];
 		uint32_t totalRunTime;
@@ -174,7 +185,7 @@ void doCommand(String str, bool echo = false) {
 			String core = systemState[i].xCoreID == tskNO_AFFINITY ? "*" : String(systemState[i].xCoreID);
 			int cpuPercentage = systemState[i].ulRunTimeCounter / (totalRunTime / 100);
 			print("%-5d%-20s%-7d%-6d%-6s%d\n",systemState[i].xTaskNumber, systemState[i].pcTaskName,
-				systemState[i].usStackHighWaterMark, systemState[i].uxCurrentPriority, core, cpuPercentage);
+				systemState[i].usStackHighWaterMark, systemState[i].uxCurrentPriority, core.c_str(), cpuPercentage);
 		}
 		delete[] systemState;
 #endif
@@ -199,7 +210,7 @@ void handleInput() {
 
 	while (Serial.available()) {
 		char c = Serial.read();
-		if (c == '\n') {
+		if (c == '\n' || c == '\r') {
 			doCommand(input);
 			input.clear();
 		} else {

flix/config.h

@@ -0,0 +1,27 @@
+// Copyright (c) 2026 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Parameter defaults
+
+#pragma once
+
+void setDefaults() {
+	// Set defaults here
+
+	#if defined(CONFIG_IDF_TARGET_ESP32S3) || defined(CONFIG_IDF_TARGET_ESP32C3)
+		pwmFrequency = 38000;
+	#endif
+
+	#ifdef FLIX2
+		imuModel = 4; // ICM-40609-D
+		imuIntPin = 10;
+		imuCsPin = 14;
+
+		motorPins[MOTOR_REAR_LEFT] = 41;
+		motorPins[MOTOR_REAR_RIGHT] = 7;
+		motorPins[MOTOR_FRONT_RIGHT] = 18;
+		motorPins[MOTOR_FRONT_LEFT] = 38;
+
+		voltagePin = 3;
+	#endif
+}

flix/control.ino

@@ -6,34 +6,9 @@
 #include "vector.h"
 #include "quaternion.h"
 #include "pid.h"
-#include "lpf.h"
+#include "filter.h"
 #include "util.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 6
-#define ROLL_I 0
-#define ROLL_D 0
-#define PITCH_P ROLL_P
-#define PITCH_I ROLL_I
-#define PITCH_D ROLL_D
-#define YAW_P 3
-#define PITCHRATE_MAX radians(360)
-#define ROLLRATE_MAX radians(360)
-#define YAWRATE_MAX radians(300)
-#define TILT_MAX radians(30)
-#define RATES_D_LPF_ALPHA 0.2 // cutoff frequency ~ 40 Hz
-
 const int RAW = 0, ACRO = 1, STAB = 2, AUTO = 3; // flight modes
 int mode = STAB;
 bool armed = false;
@@ -44,14 +19,15 @@ Vector ratesExtra; // feedforward rates
 Vector torqueTarget;
 float thrustTarget;
 
-PID rollRatePID(ROLLRATE_P, ROLLRATE_I, ROLLRATE_D, ROLLRATE_I_LIM, RATES_D_LPF_ALPHA);
+PID rollRatePID(0.05, 0.2, 0.001, 0.3, 0.2);
-PID pitchRatePID(PITCHRATE_P, PITCHRATE_I, PITCHRATE_D, PITCHRATE_I_LIM, RATES_D_LPF_ALPHA);
+PID pitchRatePID(0.05, 0.2, 0.001, 0.3, 0.2);
-PID yawRatePID(YAWRATE_P, YAWRATE_I, YAWRATE_D);
+PID yawRatePID(0.3, 0, 0, 0.3);
-PID rollPID(ROLL_P, ROLL_I, ROLL_D);
+PID rollPID(6);
-PID pitchPID(PITCH_P, PITCH_I, PITCH_D);
+PID pitchPID(6);
-PID yawPID(YAW_P, 0, 0);
+PID yawPID(3);
-Vector maxRate(ROLLRATE_MAX, PITCHRATE_MAX, YAWRATE_MAX);
+Vector maxRate(radians(360), radians(360), radians(360));
-float tiltMax = TILT_MAX;
+float tiltMax = radians(30);
+int flightModes[] = {STAB, STAB, STAB}; // map for rc mode switch
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
 extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlMode;
@@ -65,9 +41,9 @@ void control() {
 }
 
 void interpretControls() {
-	if (controlMode < 0.25) mode = STAB;
+	if (controlMode < 0.25) mode = flightModes[0];
-	if (controlMode < 0.75) mode = STAB;
+	else if (controlMode <= 0.75) mode = flightModes[1];
-	if (controlMode > 0.75) mode = STAB;
+	else if (controlMode > 0.75) mode = flightModes[2];
 
 	if (mode == AUTO) return; // pilot is not effective in AUTO mode
 
@@ -148,12 +124,26 @@ void controlTorque() {
 	motors[MOTOR_REAR_LEFT] = thrustTarget + torqueTarget.x + torqueTarget.y - torqueTarget.z;
 	motors[MOTOR_REAR_RIGHT] = thrustTarget - torqueTarget.x + torqueTarget.y + torqueTarget.z;
 
+	// Prioritize angle control over thrust control
+	desaturate(motors[MOTOR_FRONT_LEFT], motors[MOTOR_FRONT_RIGHT], motors[MOTOR_REAR_LEFT], motors[MOTOR_REAR_RIGHT]);
+
 	motors[0] = constrain(motors[0], 0, 1);
 	motors[1] = constrain(motors[1], 0, 1);
 	motors[2] = constrain(motors[2], 0, 1);
 	motors[3] = constrain(motors[3], 0, 1);
 }
 
+void desaturate(float& a, float& b, float& c, float& d) {
+	float maxThrust = max(max(a, b), max(c, d));
+	if (maxThrust > 1) {
+		float diff = maxThrust - 1;
+		a -= diff;
+		b -= diff;
+		c -= diff;
+		d -= diff;
+	}
+}
+
 const char* getModeName() {
 	switch (mode) {
 		case RAW: return "RAW";

flix/estimate.ino

@@ -1,11 +1,11 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 
-// Attitude estimation from gyro and accelerometer
+// Attitude estimation using gyro and accelerometer
 
 #include "quaternion.h"
 #include "vector.h"
-#include "lpf.h"
+#include "filter.h"
 #include "util.h"
 
 Vector rates; // estimated angular rates, rad/s
@@ -13,11 +13,13 @@ Quaternion attitude; // estimated attitude
 bool landed;
 
 float accWeight = 0.003;
+float levelWeight = 0.0002;
 LowPassFilter<Vector> ratesFilter(0.2); // cutoff frequency ~ 40 Hz
 
 void estimate() {
 	applyGyro();
 	applyAcc();
+	applyLevel();
 }
 
 void applyGyro() {
@@ -30,8 +32,7 @@ void applyGyro() {
 
 void applyAcc() {
 	// test should we apply accelerometer gravity correction
-	float accNorm = acc.norm();
+	landed = !motorsActive() && abs(acc.norm() - ONE_G) < ONE_G * 0.1f;
-	landed = !motorsActive() && abs(accNorm - ONE_G) < ONE_G * 0.1f;
 
 	if (!landed) return;
 
@@ -42,3 +43,13 @@ void applyAcc() {
 	// apply correction
 	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(correction));
 }
+
+void applyLevel() {
+	if (landed) return;
+	if (thrustTarget < 0.1) return; // skip at idle thrust
+
+	// assume the pilot keeps the drone more or less level in flight
+	Vector up = Quaternion::rotateVector(Vector(0, 0, 1), attitude);
+	Vector correction = Vector::rotationVectorBetween(Vector(0, 0, 1), up) * levelWeight;
+	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(correction));
+}

flix/filter.h

@@ -14,6 +14,10 @@ public:
 	LowPassFilter(float alpha): alpha(alpha) {};
 
 	T update(const T input) {
+		if (!init) {
+			init = true;
+			return output = input;
+		}
 		return output += alpha * (input - output);
 	}
 
@@ -22,6 +26,9 @@ public:
 	}
 
 	void reset() {
-		output = T(); // set to zero
+		init = false;
 	}
+
+private:
+	bool init = false;
 };

flix/flix.ino

@@ -17,12 +17,12 @@ extern float motors[4];
 
 void setup() {
 	Serial.begin(115200);
-	print("Initializing flix\n");
+	print("Initializing Flix\n");
-	disableBrownOut();
 	setupParameters();
+	setupPower();
 	setupLED();
-	setupMotors();
 	setLED(true);
+	setupMotors();
 	setupWiFi();
 	setupIMU();
 	setupRC();
@@ -39,6 +39,7 @@ void loop() {
 	sendMotors();
 	handleInput();
 	processMavlink();
+	readVoltage();
 	logData();
 	syncParameters();
 }

flix/imu.ino

@@ -4,13 +4,18 @@
 // Work with the IMU sensor
 
 #include <SPI.h>
+#include <Wire.h>
 #include <FlixPeriph.h>
 #include "vector.h"
-#include "lpf.h"
+#include "filter.h"
 #include "util.h"
 
-MPU9250 imu(SPI);
+IMU *imu;
-Vector imuRotation(0, 0, -PI / 2); // imu orientation as Euler angles
+int imuModel = -1; // 1 - MPU9250, 2 - ICM20948, 3 - MPU6050, 4 - ICM40609D
+int imuBus = 0; // 0 - SPI, 1 - I2C
+int imuSckPin = SCK, imuMisoPin = MISO, imuMosiPin = MOSI, imuCsPin = SS, imuIntPin = -1;
+int imuSdaPin = SDA, imuSclPin = SCL;
+Vector imuRotation(0, 0, PI / 2); // imu orientation as Euler angles
 
 Vector gyro; // gyroscope output, rad/s
 Vector gyroBias;
@@ -23,27 +28,42 @@ LowPassFilter<Vector> gyroBiasFilter(0.001);
 
 void setupIMU() {
 	print("Setup IMU\n");
-	imu.begin();
+	free(imu);
+	if (imuModel == 3) imuBus = 1; // MPU6050 is I2C only
+
+	if (imuBus == 0) {
+		// SPI connection
+		SPI.begin(imuSckPin, imuMisoPin, imuMosiPin);
+		imu = IMU::create(imuModel, SPI, imuCsPin, imuIntPin);
+	} else {
+		// I2C connection
+		Wire.setPins(imuSdaPin, imuSclPin);
+		imu = IMU::create(imuModel, Wire, imuIntPin);
+	}
+
+	imu->begin();
 	configureIMU();
 }
 
 void configureIMU() {
-	imu.setAccelRange(imu.ACCEL_RANGE_4G);
+	imu->setAccelRange(IMU::ACCEL_RANGE_4G);
-	imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
+	imu->setGyroRange(IMU::GYRO_RANGE_2000DPS);
-	imu.setDLPF(imu.DLPF_MAX);
+	imu->setDLPF(IMU::DLPF_MAX);
-	imu.setRate(imu.RATE_1KHZ_APPROX);
+	imu->setRate(IMU::RATE_1KHZ_APPROX);
-	imu.setupInterrupt();
+	imu->setupInterrupt();
 }
 
 void readIMU() {
-	imu.waitForData();
+	imu->waitForData();
-	imu.getGyro(gyro.x, gyro.y, gyro.z);
+	imu->getGyro(gyro.x, gyro.y, gyro.z);
-	imu.getAccel(acc.x, acc.y, acc.z);
+	imu->getAccel(acc.x, acc.y, acc.z);
 	calibrateGyroOnce();
-	// apply scale and bias
+
+	// Apply scale and bias
 	acc = (acc - accBias) / accScale;
 	gyro = gyro - gyroBias;
-	// rotate to body frame
+
+	// Rotate to body frame
 	Quaternion rotation = Quaternion::fromEuler(imuRotation);
 	acc = Quaternion::rotateVector(acc, rotation.inversed());
 	gyro = Quaternion::rotateVector(gyro, rotation.inversed());
@@ -52,12 +72,13 @@ void readIMU() {
 void calibrateGyroOnce() {
 	static Delay landedDelay(2);
 	if (!landedDelay.update(landed)) return; // calibrate only if definitely stationary
+
 	gyroBias = gyroBiasFilter.update(gyro);
 }
 
 void calibrateAccel() {
 	print("Calibrating accelerometer\n");
-	imu.setAccelRange(imu.ACCEL_RANGE_2G); // the most sensitive mode
+	imu->setAccelRange(IMU::ACCEL_RANGE_2G); // the most sensitive mode
 
 	print("1/6 Place level [8 sec]\n");
 	pause(8);
@@ -91,9 +112,9 @@ void calibrateAccelOnce() {
 	// Compute the average of the accelerometer readings
 	acc = Vector(0, 0, 0);
 	for (int i = 0; i < samples; i++) {
-		imu.waitForData();
+		imu->waitForData();
 		Vector sample;
-		imu.getAccel(sample.x, sample.y, sample.z);
+		imu->getAccel(sample.x, sample.y, sample.z);
 		acc = acc + sample;
 	}
 	acc = acc / samples;
@@ -105,6 +126,7 @@ void calibrateAccelOnce() {
 	if (acc.x < accMin.x) accMin.x = acc.x;
 	if (acc.y < accMin.y) accMin.y = acc.y;
 	if (acc.z < accMin.z) accMin.z = acc.z;
+
 	// Compute scale and bias
 	accScale = (accMax - accMin) / 2 / ONE_G;
 	accBias = (accMax + accMin) / 2;
@@ -117,16 +139,18 @@ void printIMUCalibration() {
 }
 
 void printIMUInfo() {
-	imu.status() ? print("status: ERROR %d\n", imu.status()) : print("status: OK\n");
+	imu->status() ? print("status: ERROR %d\n", imu->status()) : print("status: OK\n");
-	print("model: %s\n", imu.getModel());
+	print("model: %s\n", imu->getModel());
-	print("who am I: 0x%02X\n", imu.whoAmI());
+	print("who am I: 0x%02X\n", imu->whoAmI());
 	print("rate: %.0f\n", loopRate);
-	print("gyro: %f %f %f\n", rates.x, rates.y, rates.z);
+	print("interrupt mode: %s\n", imuIntPin != -1 ? "pin" : "timer");
+	print("temperature: %.1f °C\n", imu->getTemp());
+	print("gyro: %f %f %f\n", gyro.x, gyro.y, gyro.z);
 	print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
-	imu.waitForData();
+	imu->waitForData();
 	Vector rawGyro, rawAcc;
-	imu.getGyro(rawGyro.x, rawGyro.y, rawGyro.z);
+	imu->getGyro(rawGyro.x, rawGyro.y, rawGyro.z);
-	imu.getAccel(rawAcc.x, rawAcc.y, rawAcc.z);
+	imu->getAccel(rawAcc.x, rawAcc.y, rawAcc.z);
 	print("raw gyro: %f %f %f\n", rawGyro.x, rawGyro.y, rawGyro.z);
 	print("raw acc: %f %f %f\n", rawAcc.x, rawAcc.y, rawAcc.z);
 }

flix/mavlink.ino

@@ -7,12 +7,18 @@
 #include "util.h"
 
 extern float controlTime;
+extern float voltage;
 
-bool mavlinkConnected = false;
-String mavlinkPrintBuffer;
 int mavlinkSysId = 1;
-Rate telemetryFast(10);
+
 Rate telemetrySlow(2);
+Rate telemetryAttitude(20);
+Rate telemetryRC(10);
+Rate telemetryMotors(10);
+Rate telemetryIMU(15);
+
+float mavlinkTime = NAN; // time of last received message
+String mavlinkPrintBuffer;
 
 void processMavlink() {
 	sendMavlink();
@@ -32,31 +38,48 @@ void sendMavlink() {
 			((mode == AUTO) ? MAV_MODE_FLAG_AUTO_ENABLED : MAV_MODE_FLAG_MANUAL_INPUT_ENABLED),
 			mode, MAV_STATE_STANDBY);
 		sendMessage(&msg);
+	}
 
-		if (!mavlinkConnected) return; // send only heartbeat until connected
+	if (!valid(mavlinkTime)) return; // send only heartbeat until connected
 
+	if (telemetrySlow) {
 		mavlink_msg_extended_sys_state_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
 			MAV_VTOL_STATE_UNDEFINED, landed ? MAV_LANDED_STATE_ON_GROUND : MAV_LANDED_STATE_IN_AIR);
 		sendMessage(&msg);
 	}
 
-	if (telemetryFast && mavlinkConnected) {
+	if (telemetrySlow && valid(voltage)) {
-		const float zeroQuat[] = {0, 0, 0, 0};
+		uint16_t voltages[] = {(uint16_t)(voltage * 1000), UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX};
-		mavlink_msg_attitude_quaternion_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		uint16_t voltagesExt[] = {0, 0, 0, 0};
-			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, zeroQuat); // convert to frd
+		float remaining = constrain(mapf(voltage, 3.4, 4.2, 0, 1), 0, 1);
+		mavlink_msg_battery_status_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, MAV_BATTERY_FUNCTION_ALL,
+			MAV_BATTERY_TYPE_LIPO, INT16_MAX, voltages, -1, -1, -1, remaining * 100, 0, MAV_BATTERY_CHARGE_STATE_OK, voltagesExt, 0, 0);
 		sendMessage(&msg);
+	}
 
+	if (telemetryAttitude) {
+		const float offset[] = {0, 0, 0, 0};
+		mavlink_msg_attitude_quaternion_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, offset); // convert to frd
+		sendMessage(&msg);
+	}
+
+	if (telemetryRC && channels[0]) { // 0 means no RC input
 		mavlink_msg_rc_channels_raw_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, controlTime * 1000, 0,
 			channels[0], channels[1], channels[2], channels[3], channels[4], channels[5], channels[6], channels[7], UINT8_MAX);
-		if (channels[0] != 0) sendMessage(&msg); // 0 means no RC input
+		sendMessage(&msg);
+	}
 
+	if (telemetryMotors) {
 		float controls[8];
 		memcpy(controls, motors, sizeof(motors));
 		mavlink_msg_actuator_control_target_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time, 0, controls);
 		sendMessage(&msg);
+	}
 
+	if (telemetryIMU) {
 		mavlink_msg_scaled_imu_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time,
-			acc.x * 1000, -acc.y * 1000, -acc.z * 1000, // convert to frd
+			acc.x / ONE_G * 1000, -acc.y / ONE_G * 1000, -acc.z / ONE_G * 1000, // convert to frd
 			gyro.x * 1000, -gyro.y * 1000, -gyro.z * 1000,
 			0, 0, 0, 0);
 		sendMessage(&msg);
@@ -72,13 +95,13 @@ void sendMessage(const void *msg) {
 void receiveMavlink() {
 	uint8_t buf[MAVLINK_MAX_PACKET_LEN];
 	int len = receiveWiFi(buf, MAVLINK_MAX_PACKET_LEN);
-	if (len) mavlinkConnected = true;
 
 	// 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)) {
+			mavlinkTime = t;
 			handleMavlink(&msg);
 		}
 	}
@@ -232,7 +255,7 @@ void handleMavlink(const void *_msg) {
 		}
 
 		if (m.command == MAV_CMD_COMPONENT_ARM_DISARM) {
-			if (m.param1 && controlThrottle > 0.05) return; // don't arm if throttle is not low
+			if (m.param1 == 1 && controlThrottle > 0.05) return; // don't arm if throttle is not low
 			accepted = true;
 			armed = m.param1 == 1;
 		}

flix/motors.ino

@@ -14,29 +14,29 @@ int pwmStop = 0;
 int pwmMin = 0;
 int pwmMax = -1; // -1 means duty cycle mode
 
-const int MOTOR_REAR_LEFT = 0;
+const int MOTOR_REAR_LEFT = 0, MOTOR_REAR_RIGHT = 1, MOTOR_FRONT_RIGHT = 2, MOTOR_FRONT_LEFT = 3;
-const int MOTOR_REAR_RIGHT = 1;
-const int MOTOR_FRONT_RIGHT = 2;
-const int MOTOR_FRONT_LEFT = 3;
 
 void setupMotors() {
-	print("Setup Motors\n");
+	print("Setup motors\n");
-	// configure pins
+	// Configure pins
 	for (int i = 0; i < 4; i++) {
+		if (motorPins[i] < 0) continue; // skip unassigned motors
 		ledcAttach(motorPins[i], pwmFrequency, pwmResolution);
+		pwmFrequency = ledcChangeFrequency(motorPins[i], pwmFrequency, pwmResolution); // when reconfiguring
 	}
 	sendMotors();
-	print("Motors initialized\n");
 }
 
 void sendMotors() {
 	for (int i = 0; i < 4; i++) {
+		if (motorPins[i] < 0) continue; // skip unassigned motors
 		ledcWrite(motorPins[i], getDutyCycle(motors[i]));
 	}
 }
 
 int getDutyCycle(float value) {
 	value = constrain(value, 0, 1);
+
 	if (pwmMax >= 0) { // pwm mode
 		float pwm = mapf(value, 0, 1, pwmMin, pwmMax);
 		if (value == 0) pwm = pwmStop;
@@ -51,9 +51,9 @@ bool motorsActive() {
 	return motors[0] != 0 || motors[1] != 0 || motors[2] != 0 || motors[3] != 0;
 }
 
-void testMotor(int n) {
+void testMotor(int n, float thrust) {
 	print("Testing motor %d\n", n);
-	motors[n] = 1;
+	motors[n] = thrust;
 	delay(50); // ESP32 may need to wait until the end of the current cycle to change duty https://github.com/espressif/arduino-esp32/issues/5306
 	sendMotors();
 	pause(3);

flix/parameters.ino

@@ -6,21 +6,27 @@
 #include <Preferences.h>
 #include "util.h"
 
-extern float channelZero[16];
+extern int channelZero[16], channelMax[16];
-extern float channelMax[16];
+extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
-extern float rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
+extern int rcRxPin, voltagePin;
-extern int wifiMode, udpLocalPort, udpRemotePort;
+extern int wifiMode, wifiLongRange, wifiBroadcast, udpLocalPort, udpRemotePort, espnowChannel;
-extern float rcLossTimeout, descendTime;
+extern float rcLossTimeout, descendTime, disarmTilt;
+extern float voltageScale;
+extern LowPassFilter<float> voltageFilter;
+
+#include "config.h"
 
 Preferences storage;
 
 struct Parameter {
-	const char *name; // max length is 15 (Preferences key limit)
+	const char *name; // max length is 15
 	bool integer;
-	union { float *f; int *i; }; // pointer to variable
+	union { float *f; int *i; }; // pointer to the variable
+	float initial; // default value
 	float cache; // what's stored in flash
-	Parameter(const char *name, float *variable) : name(name), integer(false), f(variable) {};
+	void (*callback)(); // called after parameter change
-	Parameter(const char *name, int *variable) : name(name), integer(true), i(variable) {};
+	Parameter(const char *name, float *variable, void (*callback)() = nullptr) : name(name), integer(false), f(variable), callback(callback) {};
+	Parameter(const char *name, int *variable, void (*callback)() = nullptr) : name(name), integer(true), i(variable), callback(callback) {};
 	float getValue() const { return integer ? *i : *f; };
 	void setValue(const float value) { if (integer) *i = value; else *f = value; };
 };
@@ -31,13 +37,17 @@ Parameter parameters[] = {
 	{"CTL_R_RATE_I", &rollRatePID.i},
 	{"CTL_R_RATE_D", &rollRatePID.d},
 	{"CTL_R_RATE_WU", &rollRatePID.windup},
+	{"CTL_R_RATE_D_A", &rollRatePID.lpf.alpha},
 	{"CTL_P_RATE_P", &pitchRatePID.p},
 	{"CTL_P_RATE_I", &pitchRatePID.i},
 	{"CTL_P_RATE_D", &pitchRatePID.d},
 	{"CTL_P_RATE_WU", &pitchRatePID.windup},
+	{"CTL_P_RATE_D_A", &pitchRatePID.lpf.alpha},
 	{"CTL_Y_RATE_P", &yawRatePID.p},
 	{"CTL_Y_RATE_I", &yawRatePID.i},
 	{"CTL_Y_RATE_D", &yawRatePID.d},
+	{"CTL_Y_RATE_WU", &yawRatePID.windup},
+	{"CTL_Y_RATE_D_A", &yawRatePID.lpf.alpha},
 	{"CTL_R_P", &rollPID.p},
 	{"CTL_R_I", &rollPID.i},
 	{"CTL_R_D", &rollPID.d},
@@ -49,7 +59,19 @@ Parameter parameters[] = {
 	{"CTL_R_RATE_MAX", &maxRate.x},
 	{"CTL_Y_RATE_MAX", &maxRate.z},
 	{"CTL_TILT_MAX", &tiltMax},
+	{"CTL_FLT_MODE_0", &flightModes[0]},
+	{"CTL_FLT_MODE_1", &flightModes[1]},
+	{"CTL_FLT_MODE_2", &flightModes[2]},
 	// imu
+	{"IMU_MODEL", &imuModel},
+	{"IMU_BUS", &imuBus},
+	{"IMU_PIN_SCK", &imuSckPin},
+	{"IMU_PIN_MISO", &imuMisoPin},
+	{"IMU_PIN_MOSI", &imuMosiPin},
+	{"IMU_PIN_CS", &imuCsPin},
+	{"IMU_PIN_SDA", &imuSdaPin},
+	{"IMU_PIN_SCL", &imuSclPin},
+	{"IMU_PIN_INT", &imuIntPin},
 	{"IMU_ROT_ROLL", &imuRotation.x},
 	{"IMU_ROT_PITCH", &imuRotation.y},
 	{"IMU_ROT_YAW", &imuRotation.z},
@@ -62,18 +84,20 @@ Parameter parameters[] = {
 	{"IMU_GYRO_BIAS_A", &gyroBiasFilter.alpha},
 	// estimate
 	{"EST_ACC_WEIGHT", &accWeight},
+	{"EST_LVL_WEIGHT", &levelWeight},
 	{"EST_RATES_LPF_A", &ratesFilter.alpha},
 	// motors
-	{"MOT_PIN_FL", &motorPins[MOTOR_FRONT_LEFT]},
+	{"MOT_PIN_FL", &motorPins[MOTOR_FRONT_LEFT], setupMotors},
-	{"MOT_PIN_FR", &motorPins[MOTOR_FRONT_RIGHT]},
+	{"MOT_PIN_FR", &motorPins[MOTOR_FRONT_RIGHT], setupMotors},
-	{"MOT_PIN_RL", &motorPins[MOTOR_REAR_LEFT]},
+	{"MOT_PIN_RL", &motorPins[MOTOR_REAR_LEFT], setupMotors},
-	{"MOT_PIN_RR", &motorPins[MOTOR_REAR_RIGHT]},
+	{"MOT_PIN_RR", &motorPins[MOTOR_REAR_RIGHT], setupMotors},
-	{"MOT_PWM_FREQ", &pwmFrequency},
+	{"MOT_PWM_FREQ", &pwmFrequency, setupMotors},
-	{"MOT_PWM_RES", &pwmResolution},
+	{"MOT_PWM_RES", &pwmResolution, setupMotors},
 	{"MOT_PWM_STOP", &pwmStop},
 	{"MOT_PWM_MIN", &pwmMin},
 	{"MOT_PWM_MAX", &pwmMax},
 	// rc
+	{"RC_RX_PIN", &rcRxPin, setupRC},
 	{"RC_ZERO_0", &channelZero[0]},
 	{"RC_ZERO_1", &channelZero[1]},
 	{"RC_ZERO_2", &channelZero[2]},
@@ -97,25 +121,39 @@ Parameter parameters[] = {
 	{"RC_MODE", &modeChannel},
 	// wifi
 	{"WIFI_MODE", &wifiMode},
-	{"WIFI_LOC_PORT", &udpLocalPort},
+	{"WIFI_PORT_LOC", &udpLocalPort},
-	{"WIFI_REM_PORT", &udpRemotePort},
+	{"WIFI_PORT_REM", &udpRemotePort},
+	{"WIFI_LONG_RANGE", &wifiLongRange},
+	{"WIFI_BROADCAST", &wifiBroadcast},
+	// espnow
+	{"ESPNOW_CHANNEL", &espnowChannel},
 	// mavlink
 	{"MAV_SYS_ID", &mavlinkSysId},
 	{"MAV_RATE_SLOW", &telemetrySlow.rate},
-	{"MAV_RATE_FAST", &telemetryFast.rate},
+	{"MAV_RATE_ATT", &telemetryAttitude.rate},
+	{"MAV_RATE_RC", &telemetryRC.rate},
+	{"MAV_RATE_MOT", &telemetryMotors.rate},
+	{"MAV_RATE_IMU", &telemetryIMU.rate},
+	// power
+	{"PWR_VOLT_PIN", &voltagePin, setupPower},
+	{"PWR_VOLT_SCALE", &voltageScale},
+	{"PWR_VOLT_LPF_A", &voltageFilter.alpha},
 	// safety
 	{"SF_RC_LOSS_TIME", &rcLossTimeout},
 	{"SF_DESCEND_TIME", &descendTime},
+	{"SF_DISARM_TILT", &disarmTilt},
 };
 
 void setupParameters() {
-	storage.begin("flix", false);
+	print("Setup parameters\n");
+	setDefaults();
+	storage.begin("flix");
 	// Read parameters from storage
 	for (auto &parameter : parameters) {
-		if (!storage.isKey(parameter.name)) {
+		parameter.initial = parameter.getValue();
-			storage.putFloat(parameter.name, parameter.getValue()); // store default value
+		if (storage.isKey(parameter.name)) {
+			parameter.setValue(storage.getFloat(parameter.name));
 		}
-		parameter.setValue(storage.getFloat(parameter.name, 0));
 		parameter.cache = parameter.getValue();
 	}
 }
@@ -148,6 +186,7 @@ bool setParameter(const char *name, const float value) {
 		if (strcasecmp(parameter.name, name) == 0) {
 			if (parameter.integer && !isfinite(value)) return false; // can't set integer to NaN or Inf
 			parameter.setValue(value);
+			if (parameter.callback) parameter.callback();
 			return true;
 		}
 	}
@@ -160,18 +199,23 @@ void syncParameters() {
 	if (motorsActive()) return; // don't use flash while flying, it may cause a delay
 
 	for (auto &parameter : parameters) {
-		if (parameter.getValue() == parameter.cache) continue; // no change
+		if (floatEquals(parameter.getValue(), parameter.cache)) continue; // no change
-		if (isnan(parameter.getValue()) && isnan(parameter.cache)) continue; // both are NaN
-		if (isinf(parameter.getValue()) && isinf(parameter.cache)) continue; // both are Inf
 
 		storage.putFloat(parameter.name, parameter.getValue());
 		parameter.cache = parameter.getValue(); // update cache
 	}
 }
 
-void printParameters() {
+void printParameters(const char *filter) {
+	print("Name             Value          [Default]\n");
 	for (auto &parameter : parameters) {
-		print("%s = %g\n", parameter.name, parameter.getValue());
+		if (strncasecmp(parameter.name, filter, strlen(filter))) continue;
+
+		if (floatEquals(parameter.getValue(), parameter.initial)) { // parameter changed
+			print("%-15s  %-13g\n", parameter.name, parameter.getValue());
+		} else {
+			print("%-15s  %-13g  [%g]\n", parameter.name, parameter.getValue(), parameter.initial);
+		}
 	}
 }
 

flix/pid.h

@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include "lpf.h"
+#include "filter.h"
 
 class PID {
 public:
@@ -18,7 +18,7 @@ public:
 
 	LowPassFilter<float> lpf; // low pass filter for derivative term
 
-	PID(float p, float i, float d, float windup = 0, float dAlpha = 1, float dtMax = 0.1) :
+	PID(float p, float i = 0, float d = 0, float windup = INFINITY, float dAlpha = 1, float dtMax = 0.1) :
 		p(p), i(i), d(d), windup(windup), lpf(dAlpha), dtMax(dtMax) {}
 
 	float update(float error) {

flix/power.ino

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

flix/rc.ino

@@ -6,33 +6,33 @@
 #include <SBUS.h>
 #include "util.h"
 
-SBUS rc(Serial2);
+SBUS rc(Serial1);
+int rcRxPin = -1; // -1 means disabled
 
 uint16_t channels[16]; // raw rc channels
-float channelZero[16]; // calibration zero values
+int channelZero[16]; // calibration zero values
-float channelMax[16]; // calibration max values
+int channelMax[16]; // calibration max values
 
 float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
 float controlMode = NAN;
 float controlTime = NAN; // time of the last controls update
 
-// Channels mapping (nan means not assigned):
+int rollChannel = -1, pitchChannel = -1, throttleChannel = -1, yawChannel = -1, modeChannel = -1; // channel mapping
-float rollChannel = NAN, pitchChannel = NAN, throttleChannel = NAN, yawChannel = NAN, modeChannel = NAN;
 
 void setupRC() {
+	if (rcRxPin < 0) return;
 	print("Setup RC\n");
-	rc.begin();
+	rc.begin(rcRxPin);
 }
 
 bool readRC() {
-	if (rc.read()) {
+	if (rcRxPin < 0) return false;
-		SBUSData data = rc.data();
+	if (!rc.read()) return false;
-		for (int i = 0; i < 16; i++) channels[i] = data.ch[i]; // copy channels data
+
+	rc.getChannels(channels);
 	normalizeRC();
 	controlTime = t;
 	return true;
-	}
-	return false;
 }
 
 void normalizeRC() {
@@ -41,30 +41,35 @@ void normalizeRC() {
 		controls[i] = mapf(channels[i], channelZero[i], channelMax[i], 0, 1);
 	}
 	// Update control values
-	controlRoll = rollChannel >= 0 ? controls[(int)rollChannel] : 0;
+	controlRoll = rollChannel < 0 ? 0 : controls[rollChannel];
-	controlPitch = pitchChannel >= 0 ? controls[(int)pitchChannel] : 0;
+	controlPitch = pitchChannel < 0 ? 0 : controls[pitchChannel];
-	controlYaw = yawChannel >= 0 ? controls[(int)yawChannel] : 0;
+	controlYaw = yawChannel < 0 ? 0 : controls[yawChannel];
-	controlThrottle = throttleChannel >= 0 ? controls[(int)throttleChannel] : 0;
+	controlThrottle = throttleChannel < 0 ? 0 : controls[throttleChannel];
-	controlMode = modeChannel >= 0 ? controls[(int)modeChannel] : NAN; // mode switch should not have affect if not set
+	controlMode = modeChannel < 0 ? NAN : controls[modeChannel]; // mode control is ineffective if not mapped
 }
 
 void calibrateRC() {
-	uint16_t zero[16];
+	if (rcRxPin < 0) {
-	uint16_t center[16];
+		print("RC_RX_PIN = %d, set the RC pin!\n", rcRxPin);
-	uint16_t max[16];
+		return;
+	}
+
+	uint16_t zero[16]; // for zero positions
+	uint16_t center[16]; // for center positions
+	uint16_t _[16]; // for unused data
 	print("1/8 Calibrating RC: put all switches to default positions [3 sec]\n");
 	pause(3);
-	calibrateRCChannel(NULL, zero, zero, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
+	calibrateRCChannel(NULL, _, zero, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
-	calibrateRCChannel(NULL, center, center, "3/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
+	calibrateRCChannel(&throttleChannel, zero, _, "3/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
-	calibrateRCChannel(&throttleChannel, zero, max, "4/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
+	calibrateRCChannel(NULL, _, center, "4/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
-	calibrateRCChannel(&yawChannel, center, max, "5/8 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
+	calibrateRCChannel(&yawChannel, center, _, "5/8 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
-	calibrateRCChannel(&pitchChannel, zero, max, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
+	calibrateRCChannel(&pitchChannel, zero, _, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
-	calibrateRCChannel(&rollChannel, zero, max, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
+	calibrateRCChannel(&rollChannel, zero, _, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
-	calibrateRCChannel(&modeChannel, zero, max, "8/8 Put mode switch to max [3 sec]\n");
+	calibrateRCChannel(&modeChannel, zero, _, "8/8 Put mode switch to max [3 sec]\n");
 	printRCCalibration();
 }
 
-void calibrateRCChannel(float *channel, uint16_t in[16], uint16_t out[16], const char *str) {
+void calibrateRCChannel(int *channel, uint16_t in[16], uint16_t out[16], const char *str) {
 	print("%s", str);
 	pause(3);
 	for (int i = 0; i < 30; i++) readRC(); // try update 30 times max
@@ -85,15 +90,15 @@ void calibrateRCChannel(float *channel, uint16_t in[16], uint16_t out[16], const
 		channelZero[ch] = in[ch];
 		channelMax[ch] = out[ch];
 	} else {
-		*channel = NAN;
+		*channel = -1;
 	}
 }
 
 void printRCCalibration() {
 	print("Control   Ch     Zero   Max\n");
-	print("Roll      %-7g%-7g%-7g\n", rollChannel, rollChannel >= 0 ? channelZero[(int)rollChannel] : NAN, rollChannel >= 0 ? channelMax[(int)rollChannel] : NAN);
+	print("Roll      %-7d%-7d%-7d\n", rollChannel, rollChannel < 0 ? 0 : channelZero[rollChannel], rollChannel < 0 ? 0 : channelMax[rollChannel]);
-	print("Pitch     %-7g%-7g%-7g\n", pitchChannel, pitchChannel >= 0 ? channelZero[(int)pitchChannel] : NAN, pitchChannel >= 0 ? channelMax[(int)pitchChannel] : NAN);
+	print("Pitch     %-7d%-7d%-7d\n", pitchChannel, pitchChannel < 0 ? 0 : channelZero[pitchChannel], pitchChannel < 0 ? 0 : channelMax[pitchChannel]);
-	print("Yaw       %-7g%-7g%-7g\n", yawChannel, yawChannel >= 0 ? channelZero[(int)yawChannel] : NAN, yawChannel >= 0 ? channelMax[(int)yawChannel] : NAN);
+	print("Yaw       %-7d%-7d%-7d\n", yawChannel, yawChannel < 0 ? 0 : channelZero[yawChannel], yawChannel < 0 ? 0 : channelMax[yawChannel]);
-	print("Throttle  %-7g%-7g%-7g\n", throttleChannel, throttleChannel >= 0 ? channelZero[(int)throttleChannel] : NAN, throttleChannel >= 0 ? channelMax[(int)throttleChannel] : NAN);
+	print("Throttle  %-7d%-7d%-7d\n", throttleChannel, throttleChannel < 0 ? 0 : channelZero[throttleChannel], throttleChannel < 0 ? 0 : channelMax[throttleChannel]);
-	print("Mode      %-7g%-7g%-7g\n", modeChannel, modeChannel >= 0 ? channelZero[(int)modeChannel] : NAN, modeChannel >= 0 ? channelMax[(int)modeChannel] : NAN);
+	print("Mode      %-7d%-7d%-7d\n", modeChannel, modeChannel < 0 ? 0 : channelZero[modeChannel], modeChannel < 0 ? 0 : channelMax[modeChannel]);
 }

flix/safety.ino

@@ -8,10 +8,12 @@ extern float controlRoll, controlPitch, controlThrottle, controlYaw;
 
 float rcLossTimeout = 1;
 float descendTime = 10;
+float disarmTilt = radians(120);
 
 void failsafe() {
 	rcLossFailsafe();
 	autoFailsafe();
+	tiltFailsafe();
 }
 
 // RC loss failsafe
@@ -36,12 +38,24 @@ void descend() {
 // Allow pilot to interrupt automatic flight
 void autoFailsafe() {
 	static float roll, pitch, yaw, throttle;
-	if (roll != controlRoll || pitch != controlPitch || yaw != controlYaw || abs(throttle - controlThrottle) > 0.05) {
+	if (abs(roll - controlRoll) > 0.05 || abs(pitch - controlPitch) > 0.05 || abs(yaw - controlYaw) > 0.05 || abs(throttle - controlThrottle) > 0.05) {
-		// controls changed
+		// controls changed and mode switch is not configured
-		if (mode == AUTO) mode = STAB; // regain control by the pilot
+		if (mode == AUTO && invalid(controlMode)) mode = STAB; // regain control by the pilot
 	}
 	roll = controlRoll;
 	pitch = controlPitch;
 	yaw = controlYaw;
 	throttle = controlThrottle;
 }
+
+// Disarm if tilted too much
+void tiltFailsafe() {
+	if (!armed) return;
+	if (mode != STAB) return;
+
+	Vector up = Quaternion::rotateVector(Vector(0, 0, 1), attitude);
+	float tilt = acos(up.z);
+	if (disarmTilt && tilt > disarmTilt) {
+		armed = false;
+	}
+}

flix/util.h

@@ -6,8 +6,7 @@
 #pragma once
 
 #include <math.h>
-#include <soc/soc.h>
+#include <ESP32_NOW_Serial.h>
-#include <soc/rtc_cntl_reg.h>
 
 const float ONE_G = 9.80665;
 extern float t;
@@ -24,6 +23,12 @@ bool valid(float x) {
 	return isfinite(x);
 }
 
+bool floatEquals(float a, float b, float epsilon = 0) {
+	if (isnan(a) && isnan(b)) return true;
+	if (a == b) return true;
+	return fabsf(a - b) <= epsilon;
+}
+
 // Wrap angle to [-PI, PI)
 float wrapAngle(float angle) {
 	angle = fmodf(angle, 2 * PI);
@@ -35,29 +40,41 @@ float wrapAngle(float angle) {
 	return angle;
 }
 
-// Disable reset on low voltage
-void disableBrownOut() {
-	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA);
-}
-
 // Trim and split string by spaces
 void splitString(String& str, String& token0, String& token1, String& token2) {
 	str.trim();
+	if (str.isEmpty()) return;
 	char chars[str.length() + 1];
 	str.toCharArray(chars, str.length() + 1);
 	token0 = strtok(chars, " ");
-	token1 = strtok(NULL, " "); // String(NULL) creates empty string
+	token1 = strtok(NULL, " ");
 	token2 = strtok(NULL, "");
+	if (token1.c_str() == NULL) token1 = "";
+	if (token2.c_str() == NULL) token2 = "";
 }
 
+// Simplified ESP-NOW Serial without resends
+class ESPNOWSerial : public ESP_NOW_Serial_Class {
+public:
+	int lost = 0;
+	using ESP_NOW_Serial_Class::ESP_NOW_Serial_Class;
+	void onSent(bool success) override {
+		if (!success) lost++;
+		ESP_NOW_Serial_Class::onSent(true); // always report success to avoid resends
+	}
+};
+
 // Rate limiter
 class Rate {
 public:
 	float rate;
-	float last = 0;
+	float last = -INFINITY;
 	Rate(float rate) : rate(rate) {}
 
 	operator bool() {
+		if (t == last) {
+			return true; // the same step
+		}
 		if (t - last >= 1 / rate) {
 			last = t;
 			return true;

flix/vector.h

@@ -105,10 +105,23 @@ public:
 	}
 
 	static Vector rotationVectorBetween(const Vector& a, const Vector& b) {
+		float an = a.norm();
+		float bn = b.norm();
+		if (an < 1e-6 || bn < 1e-6) {
+			return Vector(0, 0, 0);
+		}
 		Vector direction = cross(a, b);
-		if (direction.zero()) {
+		if (direction.norm() < 1e-6) { // vectors are parallel
-			// vectors are opposite, return any perpendicular vector
+			if (dot(a, b) > 0) { // same direction
-			return cross(a, Vector(1, 0, 0));
+				return Vector(0, 0, 0);
+			}
+			// opposite direction
+			Vector perp = cross(a, Vector(1, 0, 0));
+			if (perp.norm() < 1e-6) {
+				perp = cross(a, Vector(0, 1, 0));
+			}
+			perp.normalize();
+			return perp * PI;
 		}
 		direction.normalize();
 		float angle = angleBetween(a, b);

flix/wifi.ino

@@ -1,76 +1,154 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 
-// Wi-Fi communication
+// Wi-Fi and ESP-NOW communication
 
 #include <WiFi.h>
 #include <WiFiAP.h>
 #include <WiFiUdp.h>
-#include "Preferences.h"
+#include <MacAddress.h>
+#include <ESP32_NOW_Serial.h>
+#include <Preferences.h>
+#include "util.h"
 
 extern Preferences storage; // use the main preferences storage
 
-const int W_DISABLED = 0, W_AP = 1, W_STA = 2;
+const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
 int wifiMode = W_AP;
+
+int wifiLongRange = 0;
+int wifiBroadcast = 0; // 0 - broadcast until connected, 1 - always broadcast
 int udpLocalPort = 14550;
 int udpRemotePort = 14550;
 IPAddress udpRemoteIP = "255.255.255.255";
-
 WiFiUDP udp;
 
+ESPNOWSerial espnow(NULL, 0, WIFI_IF_AP);
+ESPNOWSerial espnowBroadcast(ESP_NOW.BROADCAST_ADDR, 0, WIFI_IF_AP);
+int espnowChannel = 6;
+
 void setupWiFi() {
 	print("Setup Wi-Fi\n");
+	WiFi.enableLongRange(wifiLongRange);
+
 	if (wifiMode == W_AP) {
 		WiFi.softAP(storage.getString("WIFI_AP_SSID", "flix").c_str(), storage.getString("WIFI_AP_PASS", "flixwifi").c_str());
-	} else if (wifiMode == W_STA) {
-		WiFi.begin(storage.getString("WIFI_STA_SSID", "").c_str(), storage.getString("WIFI_STA_PASS", "").c_str());
-	}
 		udp.begin(udpLocalPort);
+	}
+
+	if (wifiMode == W_STA) {
+		WiFi.begin(storage.getString("WIFI_STA_SSID", "").c_str(), storage.getString("WIFI_STA_PASS", "").c_str());
+		udp.begin(udpLocalPort);
+	}
+
+	if (wifiMode == W_ESPNOW) {
+		WiFi.mode(WIFI_AP);
+		WiFi.setChannel(espnowChannel);
+		espnow.addr(MacAddress(storage.getString("ESPNOW_PEER_MAC", "FF:FF:FF:FF:FF:FF").c_str()));
+		String key = storage.getString("ESPNOW_PEER_KEY", "");
+		espnow.setKey(key.isEmpty() ? nullptr : (const uint8_t *)key.c_str());
+		espnow.begin();
+		espnowBroadcast.begin();
+	}
+
+	WiFi.setSleep(false); // disable power save
 }
 
 void sendWiFi(const uint8_t *buf, int len) {
+	if (espnow) {
+		espnow.write(buf, len);
+
+		static Rate discovery(2);
+		if (espnow.isEncrypted() && discovery) espnowBroadcast.write((const uint8_t *)"flix", 4); // broadcast message to help finding this device
+		return;
+	}
+
 	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return;
-	udp.beginPacket(udpRemoteIP, udpRemotePort);
+
+	bool broadcast = wifiBroadcast || !(t - mavlinkTime < 5); // broadcast if lost connection
+	udp.beginPacket(broadcast ? IPAddress(255, 255, 255, 255) : udpRemoteIP, udpRemotePort);
 	udp.write(buf, len);
 	udp.endPacket();
 }
 
 int receiveWiFi(uint8_t *buf, int len) {
+	if (espnow) {
+		return espnow.read(buf, len);
+	}
+
+	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return 0;
+
 	udp.parsePacket();
 	if (udp.remoteIP()) udpRemoteIP = udp.remoteIP();
 	return udp.read(buf, len);
 }
 
 void printWiFiInfo() {
-	if (WiFi.getMode() == WIFI_MODE_AP) {
+	if (espnow) {
+		print("Mode: ESP-NOW\n");
+		print("ESP-NOW version: %d\n", ESP_NOW.getVersion());
+		print("Max packet size: %d\n", ESP_NOW.getMaxDataLen());
+		print("MAC: %s\n", WiFi.softAPmacAddress().c_str());
+		print("Peer MAC: %s\n", MacAddress(espnow.addr()).toString().c_str());
+		print("Encrypted: %d\n", espnow.isEncrypted());
+		print("Channel: %d\n", espnow.getChannel());
+		print("Lost packets: %d\n", espnow.lost);
+	} else if (WiFi.getMode() == WIFI_MODE_AP) {
 		print("Mode: Access Point (AP)\n");
 		print("MAC: %s\n", WiFi.softAPmacAddress().c_str());
 		print("SSID: %s\n", WiFi.softAPSSID().c_str());
 		print("Password: ***\n");
+		print("Channel: %d\n", WiFi.channel());
 		print("Clients: %d\n", WiFi.softAPgetStationNum());
 		print("IP: %s\n", WiFi.softAPIP().toString().c_str());
+		print("Remote IP: %s\n", udpRemoteIP.toString().c_str());
 	} else if (WiFi.getMode() == WIFI_MODE_STA) {
 		print("Mode: Client (STA)\n");
 		print("Connected: %d\n", WiFi.isConnected());
 		print("MAC: %s\n", WiFi.macAddress().c_str());
 		print("SSID: %s\n", WiFi.SSID().c_str());
 		print("Password: ***\n");
+		print("Channel: %d\n", WiFi.channel());
+		print("RSSI: %d dBm\n", WiFi.RSSI());
 		print("IP: %s\n", WiFi.localIP().toString().c_str());
+		print("Remote IP: %s\n", udpRemoteIP.toString().c_str());
 	} else {
 		print("Mode: Disabled\n");
-		return;
 	}
-	print("Remote IP: %s\n", udpRemoteIP.toString().c_str());
+	print("MAVLink connected: %d\n", valid(mavlinkTime));
-	print("MAVLink connected: %d\n", mavlinkConnected);
 }
 
-void configWiFi(bool ap, const char *ssid, const char *password) {
+void configWiFi(int mode, const char *first, const char *second) {
-	if (ap) {
+	MacAddress mac;
-		storage.putString("WIFI_AP_SSID", ssid);
+	if (mode == W_AP && strlen(first) > 0 && strlen(second) >= 8) {
-		storage.putString("WIFI_AP_PASS", password);
+		storage.putString("WIFI_AP_SSID", first);
+		storage.putString("WIFI_AP_PASS", second);
+	} else if (mode == W_STA && strlen(first) > 0 && strlen(second) >= 8) {
+		storage.putString("WIFI_STA_SSID", first);
+		storage.putString("WIFI_STA_PASS", second);
+	} else if (mode == W_ESPNOW && mac.fromString(first)) {
+		storage.putString("ESPNOW_PEER_MAC", first);
+		storage.putString("ESPNOW_PEER_KEY", strlen(second) == ESP_NOW_KEY_LEN ? second : "");
 	} else {
-		storage.putString("WIFI_STA_SSID", ssid);
+		print("Invalid configuration\n");
-		storage.putString("WIFI_STA_PASS", password);
+		return;
 	}
 	print("✓ Reboot to apply new settings\n");
 }
+
+void setWiFiMode(const String& mode) {
+	if (mode == "ap") {
+		wifiMode = W_AP;
+	} else if (mode == "sta") {
+		wifiMode = W_STA;
+	} else if (mode == "espnow") {
+		wifiMode = W_ESPNOW;
+	} else if (mode == "off") {
+		wifiMode = W_DISABLED;
+	} else {
+		print("Invalid Wi-Fi mode\n");
+		return;
+	}
+	static const char *modes[] = {"Disabled", "Access Point (AP)", "Client (STA)", "ESP-NOW"};
+	print("✓ Wi-Fi mode set to %s, reboot to apply\n", modes[wifiMode]);
+}

gazebo/Arduino.h

@@ -21,6 +21,8 @@
 #define degrees(rad) ((rad)*RAD_TO_DEG)
 
 #define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
+template<typename T> T max(T a, T b) { return a > b ? a : b; }
+template<typename T> T min(T a, T b) { return a < b ? a : b; }
 
 long map(long x, long in_min, long in_max, long out_min, long out_max) {
 	const long run = in_max - in_min;
@@ -149,7 +151,7 @@ public:
 	void setRxInvert(bool invert) {};
 };
 
-HardwareSerial Serial, Serial2;
+HardwareSerial Serial, Serial1, Serial2;
 
 class EspClass {
 public:
@@ -165,6 +167,9 @@ void delay(uint32_t ms) {
 
 bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution) { return true; }
 bool ledcWrite(uint8_t pin, uint32_t duty) { return true; }
+uint32_t ledcChangeFrequency(uint8_t pin, uint32_t freq, uint8_t resolution) { return freq; }
+int8_t digitalPinToAnalogChannel(uint8_t pin) { return -1; }
+uint32_t analogReadMilliVolts(uint8_t pin) { return 0; }
 
 unsigned long __micros;
 unsigned long __resetTime = 0;

gazebo/ESP32_NOW_Serial.h

@@ -0,0 +1,12 @@
+// Dummy file for the simulator
+
+class ESP_NOW_Peer {
+protected:
+	size_t send(const uint8_t *data, int len) { return 0; }
+};
+
+class ESP_NOW_Serial_Class : public ESP_NOW_Peer {
+public:
+	virtual void onSent(bool success) {};
+	virtual size_t write(const uint8_t *data, size_t len) { return 0; };
+};

gazebo/SBUS.h

@@ -13,14 +13,13 @@ class SBUS {
 public:
 	SBUS(HardwareSerial& bus, const bool inv = true) {};
 	SBUS(HardwareSerial& bus, const int8_t rxpin, const int8_t txpin, const bool inv = true) {};
-	void begin() {};
+	void begin(int rxpin = -1, int txpin = -1, bool inv = true, bool fast = false) {};
 	bool read() { return joystickInit(); };
-	SBUSData data() {
+	void getChannels(uint16_t (&channels)[16]) const {
-		SBUSData data;
+		int16_t ch[16];
-		joystickGet(data.ch);
+		joystickGet(ch);
 		for (int i = 0; i < 16; i++) {
-			data.ch[i] = map(data.ch[i], -32768, 32767, 1000, 2000); // convert to pulse width style
+			channels[i] = map(ch[i], -32768, 32767, 1000, 2000); // convert to pulse width style
 		}
-		return data;
 	};
 };

gazebo/flix.h

@@ -9,6 +9,7 @@
 #include "quaternion.h"
 #include "Arduino.h"
 #include "wifi.h"
+#include "filter.h"
 
 extern float t, dt;
 extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
@@ -19,29 +20,36 @@ extern float motors[4];
 
 Vector gyro, acc, imuRotation;
 Vector accBias, gyroBias, accScale(1, 1, 1);
+LowPassFilter<Vector> gyroBiasFilter(0);
+int imuModel = 1, imuBus = 0;
+int imuSckPin = 0, imuMisoPin = 0, imuMosiPin = 0, imuCsPin = -1, imuIntPin = -1;
+int imuSdaPin = 0, imuSclPin = 0;
 
 // declarations
 void step();
 void computeLoopRate();
 void applyGyro();
 void applyAcc();
+void applyLevel();
 void control();
 void interpretControls();
 void controlAttitude();
 void controlRates();
 void controlTorque();
+void desaturate(float& a, float& b, float& c, float& d);
 const char* getModeName();
 void sendMotors();
 int getDutyCycle(float value);
 bool motorsActive();
-void testMotor(int n);
+void testMotor(int, float);
 void print(const char* format, ...);
 void pause(float duration);
 void doCommand(String str, bool echo);
 void handleInput();
+void setupRC();
 void normalizeRC();
 void calibrateRC();
-void calibrateRCChannel(float *channel, uint16_t zero[16], uint16_t max[16], const char *str);
+void calibrateRCChannel(int*, uint16_t[16], uint16_t[16], const char*);
 void printRCCalibration();
 void printLogHeader();
 void printLogData();
@@ -53,23 +61,25 @@ void handleMavlink(const void *_msg);
 void mavlinkPrint(const char* str);
 void sendMavlinkPrint();
 inline Quaternion fluToFrd(const Quaternion &q);
+void setupPower();
 void failsafe();
 void rcLossFailsafe();
 void descend();
 void autoFailsafe();
+void tiltFailsafe();
 int parametersCount();
 const char *getParameterName(int index);
 float getParameter(int index);
 float getParameter(const char *name);
 bool setParameter(const char *name, const float value);
-void printParameters();
+void printParameters(const char *filter);
 void resetParameters();
 
 // mocks
 void setLED(bool on) {};
-void calibrateGyro() { print("Skip gyro calibrating\n"); };
 void calibrateAccel() { print("Skip accel calibrating\n"); };
 void printIMUCalibration() { print("cal: N/A\n"); };
 void printIMUInfo() {};
 void printWiFiInfo() {};
 void configWiFi(bool, const char*, const char*) { print("Skip WiFi config\n"); };
+void setWiFiMode(const String& mode) { print("Skip WiFi mode set\n"); };

gazebo/simulator.cpp

@@ -23,10 +23,11 @@
 #include "estimate.ino"
 #include "safety.ino"
 #include "log.ino"
-#include "lpf.h"
+#include "filter.h"
 #include "mavlink.ino"
 #include "motors.ino"
 #include "parameters.ino"
+#include "power.ino"
 #include "rc.ino"
 #include "time.ino"
 
@@ -54,6 +55,7 @@ public:
 		initNode();
 		Serial.begin(0);
 		setupParameters();
+		rcRxPin = 1; // set rc pin to enable rc reading
 		gzmsg << "Flix plugin loaded" << endl;
 	}
 
@@ -72,6 +74,8 @@ public:
 		gyro = Vector(imu->AngularVelocity().X(), imu->AngularVelocity().Y(), imu->AngularVelocity().Z());
 		acc = this->accFilter.update(Vector(imu->LinearAcceleration().X(), imu->LinearAcceleration().Y(), imu->LinearAcceleration().Z()));
 
+		voltage = 4.2f; // dummy voltage value
+
 		readRC();
 		estimate();
 

gazebo/soc/soc.h

@@ -1,4 +1,3 @@
 // Dummy file to make it possible to compile simulator with Flix' util.h
 
-#define WRITE_PERI_REG(addr, val) {}
 #define REG_CLR_BIT(_r, _b) {}

gazebo/wifi.h

@@ -11,9 +11,16 @@
 #include <sys/poll.h>
 #include <gazebo/gazebo.hh>
 
-#define WIFI_UDP_PORT 14580
+// Mocks
-#define WIFI_UDP_REMOTE_PORT 14550
+int wifiMode = 1;
-#define WIFI_UDP_REMOTE_ADDR "255.255.255.255"
+int wifiLongRange = 0;
+int wifiBroadcast = 0;
+int espnowChannel = 6;
+const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
+
+int udpLocalPort = 14580;
+int udpRemotePort = 14550;
+const char *udpRemoteIP = "255.255.255.255";
 
 int wifiSocket;
 
@@ -22,22 +29,22 @@ void setupWiFi() {
 	sockaddr_in addr; // local address
 	addr.sin_family = AF_INET;
 	addr.sin_addr.s_addr = INADDR_ANY;
-	addr.sin_port = htons(WIFI_UDP_PORT);
+	addr.sin_port = htons(udpLocalPort);
 	if (bind(wifiSocket, (sockaddr *)&addr, sizeof(addr))) {
-		gzerr << "Failed to bind WiFi UDP socket on port " << WIFI_UDP_PORT << std::endl;
+		gzerr << "Failed to bind WiFi UDP socket on port " << udpLocalPort << std::endl;
 		return;
 	}
 	int broadcast = 1;
 	setsockopt(wifiSocket, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof(broadcast)); // enable broadcast
-	gzmsg << "WiFi UDP socket initialized on port " << WIFI_UDP_PORT << " (remote port " << WIFI_UDP_REMOTE_PORT << ")" << std::endl;
+	gzmsg << "WiFi UDP socket initialized on port " << udpLocalPort << " (remote port " << udpRemotePort << ")" << std::endl;
 }
 
 void sendWiFi(const uint8_t *buf, int len) {
 	if (wifiSocket == 0) setupWiFi();
 	sockaddr_in addr; // remote address
 	addr.sin_family = AF_INET;
-	addr.sin_addr.s_addr = inet_addr(WIFI_UDP_REMOTE_ADDR);
+	addr.sin_addr.s_addr = inet_addr(udpRemoteIP);
-	addr.sin_port = htons(WIFI_UDP_REMOTE_PORT);
+	addr.sin_port = htons(udpRemotePort);
 	sendto(wifiSocket, buf, len, 0, (sockaddr *)&addr, sizeof(addr));
 }
 

tools/espnow-proxy/README.md

@@ -0,0 +1,3 @@
+# ESPNOW-proxy
+
+Proxy sketch for using ESP-NOW connection with Flix drone.

tools/espnow-proxy/espnow-proxy.ino

@@ -0,0 +1,88 @@
+// Copyright (c) 2026 Oleg Kalachev <okalachev@gmail.com>
+// Repository: https://github.com/okalachev/flix
+
+// Proxy for ESP-NOW connection
+
+#include <vector>
+#include <WiFi.h>
+#include <ESP32_NOW_Serial.h>
+#include <MacAddress.h>
+#include <MAVLink.h>
+#include <Preferences.h>
+#include "../../flix/util.h"
+
+const int CHANNEL = 6;
+char key[ESP_NOW_KEY_LEN + 1] = {0}; // with trailing null
+
+Preferences storage;
+
+std::vector<ESPNOWSerial *> peers;
+
+void onNewPeer(const esp_now_recv_info_t *info, const uint8_t *data, int len, void *arg) {
+	if (len != 4 || memcmp(data, "flix", 4) != 0) return; // check if discovery message
+
+	Serial.printf("New peer: " MACSTR "\n", MAC2STR(info->src_addr));
+	ESPNOWSerial *link = new ESPNOWSerial(info->src_addr, CHANNEL, WIFI_IF_AP);
+	link->begin();
+	link->setKey((const uint8_t *)key);
+	peers.push_back(link);
+}
+
+void setup() {
+	Serial.begin(115200);
+	WiFi.mode(WIFI_AP);
+	WiFi.setSleep(false);
+	WiFi.setChannel(CHANNEL);
+
+	ESP_NOW.onNewPeer(onNewPeer, NULL);
+	ESP_NOW.begin();
+
+	storage.begin("espnow-proxy");
+	if (!storage.isKey("key")) {
+		generateRandomKey();
+		storage.putString("key", key);
+	}
+	strcpy(key, storage.getString("key").c_str());
+
+	// Discover the first peer
+	while (peers.empty()) {
+		Serial.printf("espnow %s %s\n", WiFi.softAPmacAddress().c_str(), key);
+		delay(500);
+	}
+}
+
+void generateRandomKey() {
+	const char chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*-_+=";
+	for (int i = 0; i < ESP_NOW_KEY_LEN; i++) {
+		key[i] = chars[random(0, strlen(chars))];
+	}
+}
+
+void loop() {
+	uint8_t buf[5000];
+
+	// Send from Serial to ESP-NOW
+	while (Serial.available() > 0) {
+		int b = Serial.read();
+		if (b < 0) {
+			break;
+		}
+
+		mavlink_message_t msg;
+		mavlink_status_t status;
+		if (mavlink_parse_char(MAVLINK_COMM_0, (uint8_t)b, &msg, &status)) {
+			int len = mavlink_msg_to_send_buffer(buf, &msg);
+			for (ESPNOWSerial *link : peers) {
+				link->write(buf, len);
+			}
+		}
+	}
+
+	// Send from ESP-NOW to Serial
+	for (ESPNOWSerial *link : peers) {
+		int len = link->read(buf, sizeof(buf));
+		if (len > 0) {
+			Serial.write(buf, len);
+		}
+	}
+}

tools/example.py

@@ -10,6 +10,7 @@ print('Connected:', flix.connected)
 print('Mode:', flix.mode)
 print('Armed:', flix.armed)
 print('Landed:', flix.landed)
+print('Voltage:', flix.voltage, 'V')
 print('Rates:', *[f'{math.degrees(r):.0f}°/s' for r in flix.rates])
 print('Attitude:', *[f'{math.degrees(a):.0f}°' for a in flix.attitude_euler])
 print('Motors:', flix.motors)
@@ -23,11 +24,11 @@ print('> imu')
 print(flix.cli('imu'))
 
 print('=== Get parameter...')
-pitch_p = flix.get_param('PITCH_P')
+pitch_p = flix.get_param('CTL_P_P')
-print('PITCH_P = ', pitch_p)
+print('CTL_P_P = ', pitch_p)
 
 print('=== Set parameter...')
-flix.set_param('PITCH_P', pitch_p)
+flix.set_param('CTL_P_P', pitch_p)
 
 print('=== Wait for gyro update...')
 print('Gyro: ', flix.wait('gyro'))

tools/pyflix/README.md

@@ -24,19 +24,22 @@ pip install pyflix
 The API is accessed through the `Flix` class:
 
 ```python
-from flix import Flix
+from pyflix import Flix
 flix = Flix()  # create a Flix object and wait for connection
 ```
 
+If using ESP-NOW connection, specify the proxy device name in `FLIX_DEVICE` environment variable or pass it to the constructor: `Flix(device='/dev/cu.usbserial-0001')`.
+
 ### Telemetry
 
-Basic telemetry is available through object properties. The property names generally match the corresponding variables in the firmware itself:
+Basic telemetry is available through object properties. The property names generally match the corresponding variables in the firmware code:
 
 ```python
 print(flix.connected)       # True if connected to the drone
 print(flix.mode)            # current flight mode (str)
 print(flix.armed)           # True if the drone is armed
 print(flix.landed)          # True if the drone is landed
+print(flix.voltage)         # battery voltage (NaN - unknown, ~0 - USB powered)
 print(flix.attitude)        # attitude quaternion [w, x, y, z]
 print(flix.attitude_euler)  # attitude as Euler angles [roll, pitch, yaw]
 print(flix.rates)           # angular rates [roll_rate, pitch_rate, yaw_rate]
@@ -95,6 +98,7 @@ Full list of events:
 |`armed`|Armed state update|Armed state *(bool)*|
 |`mode`|Flight mode update|Flight mode *(str)*|
 |`landed`|Landed state update|Landed state *(bool)*|
+|`voltage`|Battery voltage update|Voltage *(float)*|
 |`print`|The drone prints text to the console|Text|
 |`attitude`|Attitude update|Attitude quaternion *(list)*|
 |`attitude_euler`|Attitude update|Euler angles *(list)*|
@@ -117,8 +121,8 @@ Full list of events:
 Get and set firmware parameters using `get_param` and `set_param` methods:
 
 ```python
-pitch_p = flix.get_param('PITCH_P')  # get parameter value
+pitch_p = flix.get_param('CTL_P_P')  # get parameter value
-flix.set_param('PITCH_P', 5)         # set parameter value
+flix.set_param('CTL_P_P', 5)         # set parameter value
 ```
 
 Execute console commands using `cli` method. This method returns the command response:
@@ -218,6 +222,13 @@ The following scripts demonstrate how to use the library:
 * [`log.py`](../log.py) — download flight logs from the drone.
 * [`example.py`](../example.py) — a simple example, prints telemetry data and waits for events.
 
+> [!TIP]
+> Set `FLIX_DEVICE` environment variable to use these tools with ESP-NOW connection, for example:
+>
+> ```bash
+> FLIX_DEVICE=/dev/cu.usbserial-0001 tools/cli.py
+> ```
+
 ## Advanced usage
 
 ### MAVLink

tools/pyflix/flix.py

@@ -5,6 +5,7 @@
 
 import os
 import time
+import math
 from queue import Queue, Empty
 from typing import Optional, Callable, List, Dict, Any, Union, Sequence
 import logging
@@ -26,6 +27,7 @@ class Flix:
     mode: str = ''
     armed: bool = False
     landed: bool = False
+    voltage: float = math.nan
     attitude: List[float]
     attitude_euler: List[float]  # roll, pitch, yaw
     rates: List[float]
@@ -42,12 +44,17 @@ class Flix:
     _print_buffer: str = ''
     _modes = ['RAW', 'ACRO', 'STAB', 'AUTO']
 
-    def __init__(self, system_id: int=1, wait_connection: bool=True):
+    def __init__(self, system_id: int=1, wait_connection: bool=True, device=os.getenv('FLIX_DEVICE')):
         if not (0 <= system_id < 256):
             raise ValueError('system_id must be in range [0, 255]')
         self._setup_mavlink()
         self.system_id = system_id
         self._init_state()
+        if device is not None:
+            # User defined connection
+            logger.debug(f'Connecting to {device}')
+            self.connection: mavutil.mavfile = mavutil.mavlink_connection(device, source_system=255)  # type: ignore
+        else:
             try:
                 # Direct connection
                 logger.debug('Listening on port 14550')
@@ -68,7 +75,7 @@ class Flix:
         self._heartbeat_thread.start()
         if wait_connection:
             self.wait('mavlink.HEARTBEAT')
-            time.sleep(0.2) # give some time to receive initial state
+            time.sleep(0.6) # give some time to receive initial state
 
     def _init_state(self):
         self.attitude = [1, 0, 0, 0]
@@ -138,7 +145,7 @@ class Flix:
         while True:
             try:
                 msg: Optional[mavlink.MAVLink_message] = self.connection.recv_match(blocking=True)
-                if msg is None:
+                if msg is None or msg.get_srcSystem() != self.system_id:
                     continue
                 self._connected()
                 msg_dict = msg.to_dict()
@@ -185,11 +192,16 @@ class Flix:
             self._trigger('motors', self.motors)
 
         if isinstance(msg, mavlink.MAVLink_scaled_imu_message):
-            self.acc = self._mavlink_to_flu([msg.xacc / 1000, msg.yacc / 1000, msg.zacc / 1000])
+            ONE_G = 9.80665
+            self.acc = self._mavlink_to_flu([msg.xacc * ONE_G / 1000, msg.yacc * ONE_G / 1000, msg.zacc * ONE_G / 1000])
             self.gyro = self._mavlink_to_flu([msg.xgyro / 1000, msg.ygyro / 1000, msg.zgyro / 1000])
             self._trigger('acc', self.acc)
             self._trigger('gyro', self.gyro)
 
+        if isinstance(msg, mavlink.MAVLink_battery_status_message):
+            self.voltage = msg.voltages[0] / 1000
+            self._trigger('voltage', self.voltage)
+
         if isinstance(msg, mavlink.MAVLink_serial_control_message):
             # new chunk of data
             text = bytes(msg.data)[:msg.count].decode('utf-8', errors='ignore')
@@ -231,7 +243,7 @@ class Flix:
             time.sleep(1)
 
     @staticmethod
-    def _mavlink_to_flu(v: List[float]) -> List[float]:
+    def _mavlink_to_flu(v: Sequence[float]) -> List[float]:
         if len(v) == 3:  # vector
             return [v[0], -v[1], -v[2]]
         elif len(v) == 4:  # quaternion
@@ -240,8 +252,8 @@ class Flix:
             raise ValueError(f'List must have 3 (vector) or 4 (quaternion) elements')
 
     @staticmethod
-    def _flu_to_mavlink(v: List[float]) -> List[float]:
+    def _flu_to_mavlink(v: Sequence[float]) -> List[float]:
-        return Flix._mavlink_to_flu(v)
+        return Flix._mavlink_to_flu(v)  # flu to mavlink is the same as mavlink to flu
 
     def _command_send(self, command: int, params: Sequence[float]):
         if len(params) != 7:
@@ -308,13 +320,13 @@ class Flix:
     def set_armed(self, armed: bool):
         self._command_send(mavlink.MAV_CMD_COMPONENT_ARM_DISARM, (1 if armed else 0, 0, 0, 0, 0, 0, 0))
 
-    def set_position(self, position: List[float], yaw: Optional[float] = None, wait: bool = False, tolerance: float = 0.1):
+    def set_position(self, position: Sequence[float], yaw: Optional[float] = None, wait: bool = False, tolerance: float = 0.1):
         raise NotImplementedError('Position control is not implemented yet')
 
-    def set_velocity(self, velocity: List[float], yaw: Optional[float] = None):
+    def set_velocity(self, velocity: Sequence[float], yaw: Optional[float] = None):
         raise NotImplementedError('Velocity control is not implemented yet')
 
-    def set_attitude(self, attitude: List[float], thrust: float):
+    def set_attitude(self, attitude: Sequence[float], thrust: float):
         if len(attitude) == 3:
             attitude = Quaternion([attitude[0], attitude[1], attitude[2]]).q  # type: ignore
         elif len(attitude) != 4:
@@ -327,7 +339,7 @@ class Flix:
                 [attitude[0], attitude[1], attitude[2], attitude[3]],
                 0, 0, 0, thrust)
 
-    def set_rates(self, rates: List[float], thrust: float):
+    def set_rates(self, rates: Sequence[float], thrust: float):
         if len(rates) != 3:
             raise ValueError('Rates must be [roll_rate, pitch_rate, yaw_rate]')
         if not (0 <= thrust <= 1):
@@ -339,7 +351,7 @@ class Flix:
                 [1, 0, 0, 0],
                 rates[0], rates[1], rates[2], thrust)
 
-    def set_motors(self, motors: List[float]):
+    def set_motors(self, motors: Sequence[float]):
         if len(motors) != 4:
             raise ValueError('motors must have 4 values')
         if not all(0 <= m <= 1 for m in motors):

tools/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pyflix"
-version = "0.11"
+version = "0.16"
 description = "Python API for Flix drone"
 authors = [{ name="Oleg Kalachev", email="okalachev@gmail.com" }]
 license = "MIT"