Implement battery voltage monitoring

Add power subsystem. Add PWR_VOLT_PIN, PWR_VOLT_SCALE, PWR_VOLT_LPF_A parameters. Support BATTERY_STATUS mavlink messages streaming. Add pw cli command. Add voltage field to pyflix library.
2026-06-28 05:56:44 +00:00 · 2026-04-21 05:18:52 +03:00
54 changed files with 215 additions and 694 deletions
@@ -23,8 +23,6 @@ jobs:
      with:
        name: firmware-binary
        path: flix/build
-    - name: Build firmware for ESP32-C3
-      run: make BOARD=esp32:esp32:esp32c3
    - name: Build firmware for ESP32-S3
      run: make BOARD=esp32:esp32:esp32s3
    - name: Check c_cpp_properties.json
@@ -4,10 +4,9 @@ build/
 tools/log/
 tools/dist/
 *.egg-info/
-.core
-.libs
+.dependencies
 .vscode/*
-!.vscode/settings.default.json
+!.vscode/settings.json
 !.vscode/c_cpp_properties.json
 !.vscode/tasks.json
 !.vscode/launch.json
@@ -6,18 +6,18 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
-				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
 				"~/Arduino/libraries/**",
 				"/usr/include/gazebo-11/",
 				"/usr/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/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",
 				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2601/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -53,18 +53,18 @@
 			"name": "Mac",
 			"includePath": [
 				"${workspaceFolder}/flix",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
 				"~/Documents/Arduino/libraries/**",
 				"/opt/homebrew/include/gazebo-11/",
 				"/opt/homebrew/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
 				"${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-x32/2601/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -103,16 +103,16 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/libraries/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.10/include/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
 				"~/Documents/Arduino/libraries/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/cores/esp32/Arduino.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.10/variants/d1_mini32/pins_arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/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-x32/2601/bin/xtensa-esp32-elf-g++.exe",
+			"compilerPath": "~/AppData/Local/Arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++.exe",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -1,7 +1,6 @@
 {
 	// 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"
@@ -1,40 +1,29 @@
-BOARD = esp32:esp32:d1_mini32:DebugLevel=error
-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*))
+BOARD = esp32:esp32:d1_mini32
+PORT := $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-*)
+PORT := $(strip $(PORT))

-export ARDUINO_NETWORK_CONNECTION_TIMEOUT := 1h
-
-build: .core .libs
+build: .dependencies
 	arduino-cli compile --fqbn $(BOARD) flix

 upload: build
 	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" flix

-erase:
-	arduino-cli burn-bootloader --fqbn $(BOARD) -p "$(PORT)" -P esptool
-
 monitor:
 	arduino-cli monitor -p "$(PORT)" -c baudrate=115200

-core .core:
-	arduino-cli core update-index --additional-urls https://espressif.github.io/arduino-esp32/package_esp32_index.json
-	arduino-cli core install esp32:esp32@3.3.10 --additional-urls https://espressif.github.io/arduino-esp32/package_esp32_index.json
-	touch .core
-
-libs .libs:
+dependencies .dependencies:
+	arduino-cli core update-index --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@3.3.6 --config-file arduino-cli.yaml
 	arduino-cli lib update-index
 	arduino-cli lib install "FlixPeriph"
 	arduino-cli lib install "MAVLink"@2.0.25
-	touch .libs
-
-upload_proxy: .core .libs
-	arduino-cli compile --fqbn $(BOARD) tools/espnow-proxy
-	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" tools/espnow-proxy
+	touch .dependencies

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

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

 simulator: build_simulator
@@ -49,6 +38,6 @@ plot:
 	plotjuggler -d $(shell ls -t tools/log/*.csv | head -n1)

 clean:
-	rm -rf gazebo/build flix/build flix/cache .core .libs
+	rm -rf gazebo/build flix/build flix/cache .dependencies

-.PHONY: build upload monitor core libs cmake build_simulator simulator log clean
+.PHONY: build upload monitor dependencies cmake build_simulator simulator log clean
@@ -21,8 +21,8 @@
 * Dedicated for education and research.
 * Made from general-purpose components.
 * Simple and clean source code in Arduino (<2k lines firmware).
-* Communication using MAVLink protocol over Wi-Fi or ESP-NOW.
-* Control with USB gamepad, remote control or smartphone.
+* Connectivity using Wi-Fi and MAVLink protocol.
+* Control using USB gamepad, remote control or smartphone.
 * Wireless command line interface and analyzing.
 * Precise simulation with Gazebo.
 * Python library for scripting and automatic flights.
@@ -47,21 +47,13 @@ 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>
-
 ## 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 articles
+## Documentation

 1. [Assembly instructions](docs/assembly.md).
 2. [Usage: build, setup and flight](docs/usage.md).
@@ -79,14 +71,14 @@ Additional articles:

 |Type|Part|Image|Quantity|
 |-|-|:-:|:-:|
-|Microcontroller board|ESP32 Mini.<br>ESP32-S3/ESP32-C3 boards are also supported.|<img src="docs/img/esp32.jpg" width=100>|1|
-|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|
+|Microcontroller board|ESP32 Mini|<img src="docs/img/esp32.jpg" width=100>|1|
+|IMU (and barometer¹) board|GY‑91, MPU-9265 (or other MPU‑9250/MPU‑6500 board)<br>ICM20948V2 (ICM‑20948)³<br>GY-521 (MPU-6050)³⁻¹|<img src="docs/img/gy-91.jpg" width=90 align=center><br><img src="docs/img/icm-20948.jpg" width=100><br><img src="docs/img/gy-521.jpg" width=100>|1|
+|Boost converter (optional, for more stable power supply)|5V output|<img src="docs/img/buck-boost.jpg" width=100>|1|
 |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 or 65 mm|<img src="docs/img/prop.jpg" width=100>|4|
+|Propeller|55 mm (alternatively 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|
-|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).<br>Make sure the battery has enough discharge rate — 25C or more!|<img src="docs/img/battery.jpg" width=100>|1|
+|Pull-down resistor|10 kΩ|<img src="docs/img/resistor10k.jpg" width=100>|4|
+|3.7V Li-Po battery|LW 952540 (or any compatible by the size)|<img src="docs/img/battery.jpg" width=100>|1|
 |Battery connector cable|MX2.0 2P female|<img src="docs/img/mx.png" width=100>|1|
 |Li-Po Battery charger|Any|<img src="docs/img/charger.jpg" width=100>|1|
 |Screws for IMU board mounting|M3x5|<img src="docs/img/screw-m3.jpg" width=100>|2|
@@ -160,16 +152,16 @@ 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)|GPIO4|
+  |Signal (TX)|GPIO4¹|

-* Optionally connect the battery voltage divider for voltage monitoring to any ADC1 pin (e. g. *GPIO32* on ESP32, *GPIO3* on ESP32-S3).
+*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.*

-  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.
+* Optionally connect the battery voltage divider for voltage monitoring to any ADC1 pin (e. g. *GPIO32* on ESP32, *GPIO3* on ESP32S3).

 ## Resources

 * Telegram channel on developing the drone and the flight controller (in Russian): https://t.me/opensourcequadcopter.
-* Official Telegram chat: https://t.me/opensourcequadcopterchat (English / Russian).
+* Official Telegram chat: https://t.me/opensourcequadcopterchat.
 * Detailed article on Habr.com about the development of the drone (in Russian): https://habr.com/ru/articles/814127/.

 ## Disclaimer
@@ -0,0 +1,5 @@
+board_manager:
+  additional_urls:
+    - https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
+network:
+  connection_timeout: 1h
@@ -28,8 +28,6 @@ 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]
@@ -67,38 +67,6 @@ 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).
@@ -5,32 +5,27 @@
 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 MPU-9250 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 MPU9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
 * **Check the chosen board**. The correct board to choose in Arduino IDE for ESP32 Mini is *WEMOS D1 MINI ESP32*.

 ## The drone doesn't fly

 Do the following:

-* **Check the battery voltage**. Use a multimeter to measure the battery voltage. The fully charged battery should have about 4.2V.
-* **Check the battery 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 the battery voltage**. Use a multimeter to measure the battery voltage. It should be in range of 3.7-4.2 V.
 * **Check if there are some startup errors**. Connect the ESP32 to the computer and check the Serial Monitor output. Use the Reset button 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.
-* **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 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).
 * **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).
@@ -38,10 +33,9 @@ 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">
-
-* **If using an SBUS receiver**:
+* **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**:
  * **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.
+* **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.
@@ -20,14 +20,13 @@ You can build and upload the firmware using either **Arduino IDE** (easier for b

 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 3.3.10. 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.
+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.
 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.
-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.
+7. [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)

@@ -58,12 +57,6 @@ 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:DebugLevel=error,FlashSize=4M,CDCOnBoot=cdc upload
-   ```
-
 See other available Make commands in [Makefile](../Makefile).

 > [!TIP]
@@ -89,9 +82,6 @@ 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)**.
@@ -122,9 +112,9 @@ You can also work with parameters using `p` command in the console. Parameter na

 ### Define IMU orientation

-The IMU orientation (relative to the drone's axes) is defined using the parameters: `IMU_ROT_ROLL`, `IMU_ROT_PITCH`, and `IMU_ROT_YAW`.
+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 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:
+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:

 <img src="img/imu-axes.png" width="200">

@@ -132,10 +122,10 @@ Use the following table to set the parameters for common IMU orientations:

 |Orientation|Parameters|Orientation|Parameters|
 |:-:|-|-|-|
-|<img src="img/imu-rot-3.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0    |<img src="img/imu-rot-7.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0|
-|<img src="img/imu-rot-2.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|<img src="img/imu-rot-6.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = -1.571|
-|<img src="img/imu-rot-1.png" width="180">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|<img src="img/imu-rot-5.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|
-|<img src="img/imu-rot-4.png" width="180"><br>☑️ **Default**|<br>`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|<img src="img/imu-rot-8.png" width="180">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|
+|<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-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-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

@@ -148,8 +138,6 @@ 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).

-Certain ESP32 models (such as ESP32-S3 and ESP32-C3) support a lower maximum PWM frequency; on these boards the parameter `MOT_PWM_FREQ` should be set to 38000 Hz.
-
 If using brushless motors and ESCs:

 1. Set the appropriate PWM using the parameters: `MOT_PWM_STOP`, `MOT_PWM_MIN`, and `MOT_PWM_MAX` (1000, 1000, and 2000 is typical).
@@ -180,7 +168,7 @@ After this setup, you should see the battery voltage in QGroundControl top panel

 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>
+    <a href="https://youtu.be/yVRN23-GISU"><img width=300 src="https://i3.ytimg.com/vi/yVRN23-GISU/maxresdefault.jpg"></a>

 3. Perform motor tests. Use the following commands **— remove the propellers before running the tests!**

@@ -202,18 +190,6 @@ There are several ways to control the drone's flight: using **smartphone** (Wi-F

 ### 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`).
@@ -226,11 +202,11 @@ There are several ways to control the drone's flight: using **smartphone** (Wi-F

 ### Control with a remote control

-If using SBUS-connected remote control you need to enable SBUS and calibrate it:
+Before using SBUS-connected remote control you need to enable SBUS and calibrate it:

 1. Connect to the drone using QGroundControl.
 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. Check if the receiver is working using `rc` command in the console.
+3. Reboot the drone to apply changes.
 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!

@@ -269,7 +245,7 @@ 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 (if configured) or using the console commands. The main flight mode is *STAB*. In order to change modes using SBUS remote control, set the parameters: `CTL_FLT_MODE_0`, `CTL_FLT_MODE_1`, and `CTL_FLT_MODE_2` to required mode numbers (0 for *RAW*, 1 for *ACRO*, 2 for *STAB*, 3 for *AUTO*).
+Flight mode is changed using mode switch on the remote control (if configured) or using the console commands. The main flight mode is *STAB*.

 #### STAB

@@ -290,7 +266,7 @@ In this mode, the pilot controls the angular rates. This control method is diffi

 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 and mode switch is not configured, the drone will switch back to *STAB* mode.
+If the pilot moves the control sticks, the drone will switch back to *STAB* mode.

 ## Wi-Fi configuration

@@ -300,8 +276,11 @@ 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 (may cause additional delays, so generally not recommended).
-* `3` — ESP-NOW mode — the drone uses ESP-NOW protocol for communication.
+* `2` — Client mode *(STA)* — the drone connects to an existing Wi-Fi network.
+* `3` — *ESP-NOW (not implemented yet)*.
+
+> [!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:

@@ -323,37 +302,6 @@ Disabling Wi-Fi:
 p WIFI_MODE 0
 ```

-### Using ESP-NOW
-
-[ESP-NOW](https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/network/esp_now.html) is a low level wireless communication protocol. It can provide lower latency, better reliability, and longer range than Wi-Fi. However, it requires a second ESP32 board to be used as a proxy for the computer.
-
-<img src="img/espnow-connection.jpg" width="600">
-
-To setup ESP-NOW communication:
-
-1. Flash the second ESP32 board with ESP-NOW proxy sketch: [`tools/espnow-proxy/espnow-proxy.ino`](../tools/espnow-proxy/espnow-proxy.ino). Use Arduino IDE or command line: `make upload_proxy`.
-
-2. Open Serial Monitor or use `make monitor` command. The ESP32 will print its MAC address and generated encryption key, for example:
-
-   ```
-   espnow 7a:c8:e3:eb:bf:e9 &PiuSysxP9+$L&5E
-   ```
-
-   Run this line as a console command on each drone you want to bind to this proxy board. [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) io 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*. QGroundControl should connect to the drone using ESP-NOW and begin showing the telemetry.
-
 ## Flight log

 After the flight, you can download the flight log for analysis wirelessly. Use the following command on your computer for that:
@@ -4,52 +4,6 @@ This page contains user-built drones based on the Flix project. Publish your pro

 ---

-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).
-
-<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.
@@ -87,17 +41,6 @@ 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.
@@ -10,7 +10,6 @@

 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;
@@ -20,44 +19,42 @@ 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 <str> - show parameters starting with str\n"
+"p <name> - show parameter\n"
 "p <name> <value> - set parameter\n"
 "preset - reset parameters\n"
 "time - show time info\n"
+"ps - show pitch/roll/yaw\n"
+"psq - show attitude quaternion\n"
 "imu - show IMU data\n"
-"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"
-"wifi ap/sta/espnow/off - set Wi-Fi 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"
+"ap <ssid> <password> - setup Wi-Fi access point\n"
+"sta <ssid> <password> - setup Wi-Fi client mode\n"
 "mot - show motor output\n"
 "log [dump] - print log header [and data]\n"
+"cr - calibrate RC\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[3000];
+	char buf[1000];
 	va_list args;
 	va_start(args, format);
 	vsnprintf(buf, sizeof(buf), format, args);
@@ -92,8 +89,10 @@ void doCommand(String str, bool echo = false) {
 	// execute command
 	if (command == "help" || command == "motd") {
 		print("%s\n", motd);
-	} else if (command == "p" && arg1 == "") {
-		printParameters(arg0.c_str());
+	} else if (command == "p" && arg0 == "") {
+		printParameters();
+	} else if (command == "p" && arg0 != "" && arg1 == "") {
+		print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
 	} else if (command == "p") {
 		bool success = setParameter(arg0.c_str(), arg1.toFloat());
 		if (success) {
@@ -107,15 +106,15 @@ 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") {
@@ -140,16 +139,12 @@ void doCommand(String str, bool echo = false) {
 		print("armed: %d\n", armed);
 	} else if (command == "pw") {
 		print("Voltage: %.1f V\n", voltage);
-	} else if (command == "wifi" && arg0 == "") {
-		printWiFiInfo();
 	} else if (command == "wifi") {
-		setWiFiMode(arg0);
+		printWiFiInfo();
 	} else if (command == "ap") {
-		configWiFi(W_AP, arg0.c_str(), arg1.c_str());
+		configWiFi(true, arg0.c_str(), arg1.c_str());
 	} else if (command == "sta") {
-		configWiFi(W_STA, arg0.c_str(), arg1.c_str());
-	} else if (command == "espnow") {
-		configWiFi(W_ESPNOW, arg0.c_str(), arg1.c_str());
+		configWiFi(false, 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]);
@@ -172,11 +167,9 @@ void doCommand(String str, bool echo = false) {
 #ifdef ESP32
 		print("Chip: %s\n", ESP.getChipModel());
 		print("Temperature: %.1f °C\n", temperatureRead());
-		print("Total RAM: %d KB\n", ESP.getHeapSize() / 1024);
-		print("Free heap: %d KB\n", ESP.getFreeHeap() / 1024);
-		print("Firmware: " __DATE__ " " __TIME__ "\n");
+		print("Free heap: %d\n", ESP.getFreeHeap());
 		// Print tasks table
-		print("Num  Task                MinSt  Prio  Core  CPU%%\n");
+		print("Num  Task                Stack  Prio  Core  CPU%%\n");
 		int taskCount = uxTaskGetNumberOfTasks();
 		TaskStatus_t *systemState = new TaskStatus_t[taskCount];
 		uint32_t totalRunTime;
@@ -185,7 +178,7 @@ 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.c_str(), cpuPercentage);
+				systemState[i].usStackHighWaterMark, systemState[i].uxCurrentPriority, core, cpuPercentage);
 		}
 		delete[] systemState;
 #endif
@@ -210,7 +203,7 @@ void handleInput() {

 	while (Serial.available()) {
 		char c = Serial.read();
-		if (c == '\n' || c == '\r') {
+		if (c == '\n') {
 			doCommand(input);
 			input.clear();
 		} else {
@@ -67,7 +67,7 @@ void control() {

 void interpretControls() {
 	if (controlMode < 0.25) mode = flightModes[0];
-	else if (controlMode <= 0.75) mode = flightModes[1];
+	else if (controlMode < 0.75) mode = flightModes[1];
 	else if (controlMode > 0.75) mode = flightModes[2];

 	if (mode == AUTO) return; // pilot is not effective in AUTO mode
@@ -149,26 +149,12 @@ 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";
@@ -13,13 +13,11 @@ 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() {
@@ -32,7 +30,8 @@ void applyGyro() {

 void applyAcc() {
 	// test should we apply accelerometer gravity correction
-	landed = !motorsActive() && abs(acc.norm() - ONE_G) < ONE_G * 0.1f;
+	float accNorm = acc.norm();
+	landed = !motorsActive() && abs(accNorm - ONE_G) < ONE_G * 0.1f;

 	if (!landed) return;

@@ -43,13 +42,3 @@ 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));
-}
@@ -18,8 +18,8 @@ extern float motors[4];
 void setup() {
 	Serial.begin(115200);
 	print("Initializing flix\n");
+	disableBrownOut();
 	setupParameters();
-	setupPower();
 	setupLED();
 	setLED(true);
 	setupMotors();
@@ -10,7 +10,7 @@
 #include "util.h"

 MPU9250 imu(SPI);
-Vector imuRotation(0, 0, PI / 2); // imu orientation as Euler angles
+Vector imuRotation(0, 0, -PI / 2); // imu orientation as Euler angles

 Vector gyro; // gyroscope output, rad/s
 Vector gyroBias;
@@ -40,12 +40,10 @@ void readIMU() {
 	imu.getGyro(gyro.x, gyro.y, gyro.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());
@@ -54,7 +52,6 @@ void readIMU() {
 void calibrateGyroOnce() {
 	static Delay landedDelay(2);
 	if (!landedDelay.update(landed)) return; // calibrate only if definitely stationary
-
 	gyroBias = gyroBiasFilter.update(gyro);
 }

@@ -108,7 +105,6 @@ 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;
@@ -125,8 +121,7 @@ void printIMUInfo() {
 	print("model: %s\n", imu.getModel());
 	print("who am I: 0x%02X\n", imu.whoAmI());
 	print("rate: %.0f\n", loopRate);
-	print("temperature: %.1f °C\n", imu.getTemp());
-	print("gyro: %f %f %f\n", gyro.x, gyro.y, gyro.z);
+	print("gyro: %f %f %f\n", rates.x, rates.y, rates.z);
 	print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
 	imu.waitForData();
 	Vector rawGyro, rawAcc;
@@ -14,10 +14,6 @@ public:
 	LowPassFilter(float alpha): alpha(alpha) {};

 	T update(const T input) {
-		if (!init) {
-			init = true;
-			return output = input;
-		}
 		return output += alpha * (input - output);
 	}

@@ -26,9 +22,6 @@ public:
 	}

 	void reset() {
-		init = false;
+		output = T(); // set to zero
 	}
-
-private:
-	bool init = false;
 };
@@ -10,12 +10,8 @@ extern float controlTime;
 extern float voltage;

 int mavlinkSysId = 1;
-
+Rate telemetryFast(10);
 Rate telemetrySlow(2);
-Rate telemetryAttitude(20);
-Rate telemetryRC(10);
-Rate telemetryMotors(10);
-Rate telemetryIMU(15);

 bool mavlinkConnected = false;
 String mavlinkPrintBuffer;
@@ -38,18 +34,14 @@ 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 (!mavlinkConnected) 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 (telemetrySlow && valid(voltage)) {
-		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};
+		uint16_t voltages[] = {voltage * 1000, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX};
 		uint16_t voltagesExt[] = {0, 0, 0, 0};
 		float remaining = constrain(mapf(voltage, 3.4, 4.2, 0, 1), 0, 1);
 		mavlink_msg_battery_status_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, MAV_BATTERY_FUNCTION_ALL,
@@ -57,29 +49,23 @@ void sendMavlink() {
 		sendMessage(&msg);
 	}

-	if (telemetryAttitude) {
+	if (telemetryFast && mavlinkConnected) {
 		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);
-		sendMessage(&msg);
-	}
+		if (channels[0] != 0) sendMessage(&msg); // 0 means no RC input

-	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 / ONE_G * 1000, -acc.y / ONE_G * 1000, -acc.z / ONE_G * 1000, // convert to frd
+			acc.x * 1000, -acc.y * 1000, -acc.z * 1000, // convert to frd
 			gyro.x * 1000, -gyro.y * 1000, -gyro.z * 1000,
 			0, 0, 0, 0);
 		sendMessage(&msg);
@@ -95,13 +81,13 @@ 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)) {
-			mavlinkConnected = true;
 			handleMavlink(&msg);
 		}
 	}
@@ -255,7 +241,7 @@ void handleMavlink(const void *_msg) {
 		}

 		if (m.command == MAV_CMD_COMPONENT_ARM_DISARM) {
-			if (m.param1 == 1 && controlThrottle > 0.05) return; // don't arm if throttle is not low
+			if (m.param1 && controlThrottle > 0.05) return; // don't arm if throttle is not low
 			accepted = true;
 			armed = m.param1 == 1;
 		}
@@ -14,13 +14,15 @@ int pwmStop = 0;
 int pwmMin = 0;
 int pwmMax = -1; // -1 means duty cycle mode

-const int MOTOR_REAR_LEFT = 0, MOTOR_REAR_RIGHT = 1, MOTOR_FRONT_RIGHT = 2, MOTOR_FRONT_LEFT = 3;
+const int MOTOR_REAR_LEFT = 0;
+const int MOTOR_REAR_RIGHT = 1;
+const int MOTOR_FRONT_RIGHT = 2;
+const int MOTOR_FRONT_LEFT = 3;

 void setupMotors() {
 	print("Setup Motors\n");
-	// Configure pins
+	// 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
 	}
@@ -30,14 +32,12 @@ void setupMotors() {

 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;
@@ -54,7 +54,7 @@ bool motorsActive() {

 void testMotor(int n) {
 	print("Testing motor %d\n", n);
-	motors[n] = 0.2;
+	motors[n] = 1;
 	delay(50); // ESP32 may need to wait until the end of the current cycle to change duty https://github.com/espressif/arduino-esp32/issues/5306
 	sendMotors();
 	pause(3);
@@ -6,11 +6,13 @@
 #include <Preferences.h>
 #include "util.h"

-extern int channelZero[16], channelMax[16];
+extern int channelZero[16];
+extern int channelMax[16];
 extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
-extern int rcRxPin, voltagePin;
-extern int wifiMode, wifiLongRange, udpLocalPort, udpRemotePort, espnowChannel;
+extern int rcRxPin;
+extern int wifiMode, udpLocalPort, udpRemotePort;
 extern float rcLossTimeout, descendTime;
+extern int voltagePin;
 extern float voltageScale;
 extern LowPassFilter<float> voltageFilter;

@@ -20,7 +22,6 @@ struct Parameter {
 	const char *name; // max length is 15
 	bool integer;
 	union { float *f; int *i; }; // pointer to the variable
-	float inital; // default value
 	float cache; // what's stored in flash
 	void (*callback)(); // called after parameter change
 	Parameter(const char *name, float *variable, void (*callback)() = nullptr) : name(name), integer(false), f(variable), callback(callback) {};
@@ -35,16 +36,13 @@ 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_D_A", &yawRatePID.lpf.alpha},
 	{"CTL_R_P", &rollPID.p},
 	{"CTL_R_I", &rollPID.i},
 	{"CTL_R_D", &rollPID.d},
@@ -72,7 +70,6 @@ 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], setupMotors},
@@ -85,7 +82,7 @@ Parameter parameters[] = {
 	{"MOT_PWM_MIN", &pwmMin},
 	{"MOT_PWM_MAX", &pwmMax},
 	// rc
-	{"RC_RX_PIN", &rcRxPin, setupRC},
+	{"RC_RX_PIN", &rcRxPin},
 	{"RC_ZERO_0", &channelZero[0]},
 	{"RC_ZERO_1", &channelZero[1]},
 	{"RC_ZERO_2", &channelZero[2]},
@@ -109,20 +106,14 @@ Parameter parameters[] = {
 	{"RC_MODE", &modeChannel},
 	// wifi
 	{"WIFI_MODE", &wifiMode},
-	{"WIFI_PORT_LOC", &udpLocalPort},
-	{"WIFI_PORT_REM", &udpRemotePort},
-	{"WIFI_LONG_RANGE", &wifiLongRange},
-	// espnow
-	{"ESPNOW_CHANNEL", &espnowChannel},
+	{"WIFI_LOC_PORT", &udpLocalPort},
+	{"WIFI_REM_PORT", &udpRemotePort},
 	// mavlink
 	{"MAV_SYS_ID", &mavlinkSysId},
 	{"MAV_RATE_SLOW", &telemetrySlow.rate},
-	{"MAV_RATE_ATT", &telemetryAttitude.rate},
-	{"MAV_RATE_RC", &telemetryRC.rate},
-	{"MAV_RATE_MOT", &telemetryMotors.rate},
-	{"MAV_RATE_IMU", &telemetryIMU.rate},
+	{"MAV_RATE_FAST", &telemetryFast.rate},
 	// power
-	{"PWR_VOLT_PIN", &voltagePin, setupPower},
+	{"PWR_VOLT_PIN", &voltagePin},
 	{"PWR_VOLT_SCALE", &voltageScale},
 	{"PWR_VOLT_LPF_A", &voltageFilter.alpha},
 	// safety
@@ -138,7 +129,6 @@ void setupParameters() {
 		if (!storage.isKey(parameter.name)) {
 			storage.putFloat(parameter.name, parameter.getValue()); // store default value
 		}
-		parameter.inital = parameter.getValue();
 		parameter.setValue(storage.getFloat(parameter.name, 0));
 		parameter.cache = parameter.getValue();
 	}
@@ -185,23 +175,17 @@ void syncParameters() {
 	if (motorsActive()) return; // don't use flash while flying, it may cause a delay

 	for (auto &parameter : parameters) {
-		if (floatEquals(parameter.getValue(), parameter.cache)) continue; // no change
+		if (parameter.getValue() == parameter.cache) continue; // no change
+		if (isnan(parameter.getValue()) && isnan(parameter.cache)) continue; // both are NAN

 		storage.putFloat(parameter.name, parameter.getValue());
 		parameter.cache = parameter.getValue(); // update cache
 	}
 }

-void printParameters(const char *filter) {
-	print("Name             Value          [Default]\n");
+void printParameters() {
 	for (auto &parameter : parameters) {
-		if (strncasecmp(parameter.name, filter, strlen(filter))) continue;
-
-		if (floatEquals(parameter.getValue(), parameter.inital)) { // parameter changed
-			print("%-15s  %-13g\n", parameter.name, parameter.getValue());
-		} else {
-			print("%-15s  %-13g  [%g]\n", parameter.name, parameter.getValue(), parameter.inital);
-		}
+		print("%s = %g\n", parameter.name, parameter.getValue());
 	}
 }

@@ -3,24 +3,16 @@

 // Power management

-#include <soc/soc.h>
-#include <soc/rtc_cntl_reg.h>
 #include "lpf.h"
 #include "util.h"

-float voltage = NAN;
+float voltage;
 LowPassFilter<float> voltageFilter(0.2);
 int voltagePin = -1;
 float voltageScale = 2;

-void setupPower() {
-	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA); // disable reset on low voltage
-	if (digitalPinToAnalogChannel(voltagePin) == -1) voltagePin = -1; // test ADC pin
-}
-
 void readVoltage() {
 	if (voltagePin < 0) return;
-
 	static Rate rate(10);
 	if (!rate) return;

@@ -6,7 +6,7 @@
 #include <SBUS.h>
 #include "util.h"

-SBUS rc(Serial1);
+SBUS rc(Serial2);
 int rcRxPin = -1; // -1 means disabled

 uint16_t channels[16]; // raw rc channels
@@ -27,12 +27,14 @@ void setupRC() {

 bool readRC() {
 	if (rcRxPin < 0) return false;
-	if (!rc.read()) return false;
-
-	rc.getChannels(channels);
-	normalizeRC();
-	controlTime = t;
-	return true;
+	if (rc.read()) {
+		SBUSData data = rc.data();
+		for (int i = 0; i < 16; i++) channels[i] = data.ch[i]; // copy channels data
+		normalizeRC();
+		controlTime = t;
+		return true;
+	}
+	return false;
 }

 void normalizeRC() {
@@ -53,19 +55,18 @@ void calibrateRC() {
 		print("RC_RX_PIN = %d, set the RC pin!\n", rcRxPin);
 		return;
 	}
-
-	uint16_t zero[16]; // for zero positions
-	uint16_t center[16]; // for center positions
-	uint16_t _[16]; // for unused data
+	uint16_t zero[16];
+	uint16_t center[16];
+	uint16_t max[16];
 	print("1/8 Calibrating RC: put all switches to default positions [3 sec]\n");
 	pause(3);
-	calibrateRCChannel(NULL, _, zero, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
-	calibrateRCChannel(&throttleChannel, zero, _, "3/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
-	calibrateRCChannel(NULL, _, center, "4/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
-	calibrateRCChannel(&yawChannel, center, _, "5/8 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
-	calibrateRCChannel(&pitchChannel, zero, _, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
-	calibrateRCChannel(&rollChannel, zero, _, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
-	calibrateRCChannel(&modeChannel, zero, _, "8/8 Put mode switch to max [3 sec]\n");
+	calibrateRCChannel(NULL, zero, zero, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
+	calibrateRCChannel(NULL, center, center, "3/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
+	calibrateRCChannel(&throttleChannel, zero, max, "4/8 Move sticks [3 sec]\n.o.     ...\n...     .o.\n...     ...\n");
+	calibrateRCChannel(&yawChannel, center, max, "5/8 Move sticks [3 sec]\n...     ...\n..o     .o.\n...     ...\n");
+	calibrateRCChannel(&pitchChannel, zero, max, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
+	calibrateRCChannel(&rollChannel, zero, max, "7/8 Move sticks [3 sec]\n...     ...\n...     ..o\n.o.     ...\n");
+	calibrateRCChannel(&modeChannel, zero, max, "8/8 Put mode switch to max [3 sec]\n");
 	printRCCalibration();
 }

@@ -37,8 +37,8 @@ void descend() {
 void autoFailsafe() {
 	static float roll, pitch, yaw, throttle;
 	if (roll != controlRoll || pitch != controlPitch || yaw != controlYaw || abs(throttle - controlThrottle) > 0.05) {
-		// controls changed and mode switch is not configured
-		if (mode == AUTO && invalid(controlMode)) mode = STAB; // regain control by the pilot
+		// controls changed
+		if (mode == AUTO) mode = STAB; // regain control by the pilot
 	}
 	roll = controlRoll;
 	pitch = controlPitch;
@@ -6,7 +6,8 @@
 #pragma once

 #include <math.h>
-#include <ESP32_NOW_Serial.h>
+#include <soc/soc.h>
+#include <soc/rtc_cntl_reg.h>

 const float ONE_G = 9.80665;
 extern float t;
@@ -23,12 +24,6 @@ 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);
@@ -40,30 +35,21 @@ 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, " ");
+	token1 = strtok(NULL, " "); // String(NULL) creates empty string
 	token2 = strtok(NULL, "");
-	if (token1.c_str() == NULL) token1 = "";
-	if (token2.c_str() == NULL) token2 = "";
 }

-// Simplified ESP-NOW Serial without 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:
@@ -72,9 +58,6 @@ public:
 	Rate(float rate) : rate(rate) {}

 	operator bool() {
-		if (t == last) {
-			return true; // the same step
-		}
 		if (t - last >= 1 / rate) {
 			last = t;
 			return true;
@@ -105,23 +105,10 @@ public:
 	}

 	static Vector rotationVectorBetween(const Vector& a, const Vector& b) {
-		float an = a.norm();
-		float bn = b.norm();
-		if (an < 1e-6 || bn < 1e-6) {
-			return Vector(0, 0, 0);
-		}
 		Vector direction = cross(a, b);
-		if (direction.norm() < 1e-6) { // vectors are parallel
-			if (dot(a, b) > 0) { // same direction
-				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;
+		if (direction.zero()) {
+			// vectors are opposite, return any perpendicular vector
+			return cross(a, Vector(1, 0, 0));
 		}
 		direction.normalize();
 		float angle = angleBetween(a, b);
@@ -1,152 +1,76 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix

-// Wi-Fi and ESP-NOW communication
+// Wi-Fi communication

 #include <WiFi.h>
 #include <WiFiAP.h>
 #include <WiFiUdp.h>
-#include <MacAddress.h>
-#include <ESP32_NOW_Serial.h>
-#include <Preferences.h>
-#include "util.h"
+#include "Preferences.h"

 extern Preferences storage; // use the main preferences storage

-const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
+const int W_DISABLED = 0, W_AP = 1, W_STA = 2;
 int wifiMode = W_AP;
-
-int wifiLongRange = 0;
 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;
+WiFiUDP udp;

 void setupWiFi() {
 	print("Setup Wi-Fi\n");
-	WiFi.enableLongRange(wifiLongRange);
-
 	if (wifiMode == W_AP) {
 		WiFi.softAP(storage.getString("WIFI_AP_SSID", "flix").c_str(), storage.getString("WIFI_AP_PASS", "flixwifi").c_str());
-		udp.begin(udpLocalPort);
-	}
-
-	if (wifiMode == W_STA) {
+	} 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_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
+	udp.begin(udpLocalPort);
 }

 void sendWiFi(const uint8_t *buf, int len) {
-	if (espnow) {
-		espnow.write(buf, len);
-
-		static Rate discovery(2);
-		if (discovery) espnowBroadcast.write((const uint8_t *)"flix", 4); // broadcast message to help finding this device
-		return;
-	}
-
 	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return;
-
 	udp.beginPacket(udpRemoteIP, udpRemotePort);
 	udp.write(buf, len);
 	udp.endPacket();
 }

 int receiveWiFi(uint8_t *buf, int len) {
-	if (espnow) {
-		return espnow.read(buf, len);
-	}
-
-	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return 0;
-
 	udp.parsePacket();
 	if (udp.remoteIP()) udpRemoteIP = udp.remoteIP();
 	return udp.read(buf, len);
 }

 void printWiFiInfo() {
-	if (espnow) {
-		print("Mode: ESP-NOW\n");
-		print("ESP-NOW version: %d\n", ESP_NOW.getVersion());
-		print("Max packet size: %d\n", ESP_NOW.getMaxDataLen());
-		print("MAC: %s\n", WiFi.softAPmacAddress().c_str());
-		print("Peer MAC: %s\n", MacAddress(espnow.addr()).toString().c_str());
-		print("Encrypted: %d\n", espnow.isEncrypted());
-		print("Channel: %d\n", espnow.getChannel());
-		print("Lost packets: %d\n", espnow.lost);
-	} else if (WiFi.getMode() == WIFI_MODE_AP) {
+	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", mavlinkConnected);
 }

-void configWiFi(int mode, const char *first, const char *second) {
-	MacAddress mac;
-	if (mode == W_AP && strlen(first) > 0 && strlen(second) >= 8) {
-		storage.putString("WIFI_AP_SSID", first);
-		storage.putString("WIFI_AP_PASS", second);
-	} else if (mode == W_STA && strlen(first) > 0 && strlen(second) >= 8) {
-		storage.putString("WIFI_STA_SSID", first);
-		storage.putString("WIFI_STA_PASS", second);
-	} else if (mode == W_ESPNOW && mac.fromString(first)) {
-		storage.putString("ESPNOW_PEER_MAC", first);
-		storage.putString("ESPNOW_PEER_KEY", strlen(second) == ESP_NOW_KEY_LEN ? second : "");
+void configWiFi(bool ap, const char *ssid, const char *password) {
+	if (ap) {
+		storage.putString("WIFI_AP_SSID", ssid);
+		storage.putString("WIFI_AP_PASS", password);
 	} else {
-		print("Invalid configuration\n");
-		return;
+		storage.putString("WIFI_STA_SSID", ssid);
+		storage.putString("WIFI_STA_PASS", password);
 	}
 	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]);
-}
@@ -21,8 +21,6 @@
 #define degrees(rad) ((rad)*RAD_TO_DEG)

 #define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
-template<typename T> T max(T a, T b) { return a > b ? a : b; }
-template<typename T> T min(T a, T b) { return a < b ? a : b; }

 long map(long x, long in_min, long in_max, long out_min, long out_max) {
 	const long run = in_max - in_min;
@@ -151,7 +149,7 @@ public:
 	void setRxInvert(bool invert) {};
 };

-HardwareSerial Serial, Serial1, Serial2;
+HardwareSerial Serial, Serial2;

 class EspClass {
 public:
@@ -168,7 +166,6 @@ void delay(uint32_t ms) {
 bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution) { return true; }
 bool ledcWrite(uint8_t pin, uint32_t duty) { return true; }
 uint32_t ledcChangeFrequency(uint8_t pin, uint32_t freq, uint8_t resolution) { return freq; }
-int8_t digitalPinToAnalogChannel(uint8_t pin) { return -1; }
 uint32_t analogReadMilliVolts(uint8_t pin) { return 0; }

 unsigned long __micros;
@@ -1,12 +0,0 @@
-// Dummy file for the simulator
-
-class ESP_NOW_Peer {
-protected:
-	size_t send(const uint8_t *data, int len) { return 0; }
-};
-
-class ESP_NOW_Serial_Class : public ESP_NOW_Peer {
-public:
-	virtual void onSent(bool success) {};
-	virtual size_t write(const uint8_t *data, size_t len) { return 0; };
-};
@@ -15,11 +15,12 @@ public:
 	SBUS(HardwareSerial& bus, const int8_t rxpin, const int8_t txpin, const bool inv = true) {};
 	void begin(int rxpin = -1, int txpin = -1, bool inv = true, bool fast = false) {};
 	bool read() { return joystickInit(); };
-	void getChannels(uint16_t (&channels)[16]) const {
-		int16_t ch[16];
-		joystickGet(ch);
+	SBUSData data() {
+		SBUSData data;
+		joystickGet(data.ch);
 		for (int i = 0; i < 16; i++) {
-			channels[i] = map(ch[i], -32768, 32767, 1000, 2000); // convert to pulse width style
+			data.ch[i] = map(data.ch[i], -32768, 32767, 1000, 2000); // convert to pulse width style
 		}
+		return data;
 	};
 };
@@ -27,13 +27,11 @@ 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);
@@ -43,10 +41,9 @@ void print(const char* format, ...);
 void pause(float duration);
 void doCommand(String str, bool echo);
 void handleInput();
-void setupRC();
 void normalizeRC();
 void calibrateRC();
-void calibrateRCChannel(int*, uint16_t[16], uint16_t[16], const char*);
+void calibrateRCChannel(int *channel, uint16_t zero[16], uint16_t max[16], const char *str);
 void printRCCalibration();
 void printLogHeader();
 void printLogData();
@@ -58,7 +55,6 @@ void handleMavlink(const void *_msg);
 void mavlinkPrint(const char* str);
 void sendMavlinkPrint();
 inline Quaternion fluToFrd(const Quaternion &q);
-void setupPower();
 void failsafe();
 void rcLossFailsafe();
 void descend();
@@ -68,7 +64,7 @@ const char *getParameterName(int index);
 float getParameter(int index);
 float getParameter(const char *name);
 bool setParameter(const char *name, const float value);
-void printParameters(const char *filter);
+void printParameters();
 void resetParameters();

 // mocks
@@ -79,4 +75,3 @@ 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"); };
@@ -73,8 +73,6 @@ public:
 		gyro = Vector(imu->AngularVelocity().X(), imu->AngularVelocity().Y(), imu->AngularVelocity().Z());
 		acc = this->accFilter.update(Vector(imu->LinearAcceleration().X(), imu->LinearAcceleration().Y(), imu->LinearAcceleration().Z()));

-		voltage = 4.2f; // dummy voltage value
-
 		readRC();
 		estimate();

@@ -1,3 +1,4 @@
 // Dummy file to make it possible to compile simulator with Flix' util.h

+#define WRITE_PERI_REG(addr, val) {}
 #define REG_CLR_BIT(_r, _b) {}
@@ -11,12 +11,7 @@
 #include <sys/poll.h>
 #include <gazebo/gazebo.hh>

-// Mocks
-int wifiMode = 1;
-int wifiLongRange = 0;
-int espnowChannel = 6;
-const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
-
+int wifiMode = 1; // mock
 int udpLocalPort = 14580;
 int udpRemotePort = 14550;
 const char *udpRemoteIP = "255.255.255.255";
@@ -1,3 +0,0 @@
-# ESPNOW-proxy
-
-Proxy sketch for using ESP-NOW connection with Flix drone.
@@ -1,88 +0,0 @@
-// 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);
-		}
-	}
-}
@@ -24,22 +24,20 @@ pip install pyflix
 The API is accessed through the `Flix` class:

 ```python
-from pyflix import Flix
+from flix 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 code:
+Basic telemetry is available through object properties. The property names generally match the corresponding variables in the firmware itself:

 ```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.voltage)         # battery voltage
 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]
@@ -5,7 +5,6 @@

 import os
 import time
-import math
 from queue import Queue, Empty
 from typing import Optional, Callable, List, Dict, Any, Union, Sequence
 import logging
@@ -27,7 +26,7 @@ class Flix:
    mode: str = ''
    armed: bool = False
    landed: bool = False
-    voltage: float = math.nan
+    voltage: float = 0
    attitude: List[float]
    attitude_euler: List[float]  # roll, pitch, yaw
    rates: List[float]
@@ -44,27 +43,22 @@ class Flix:
    _print_buffer: str = ''
    _modes = ['RAW', 'ACRO', 'STAB', 'AUTO']

-    def __init__(self, system_id: int=1, wait_connection: bool=True, device=os.getenv('FLIX_DEVICE')):
+    def __init__(self, system_id: int=1, wait_connection: bool=True):
        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')
-                self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14550', source_system=255)  # type: ignore
-            except OSError as e:
-                if e.errno != errno.EADDRINUSE:
-                    raise
-                # Port busy - using proxy
-                logger.debug('Listening on port 14555 (proxy)')
-                self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14555', source_system=254)  # type: ignore
+        try:
+            # Direct connection
+            logger.debug('Listening on port 14550')
+            self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14550', source_system=255)  # type: ignore
+        except OSError as e:
+            if e.errno != errno.EADDRINUSE:
+                raise
+            # Port busy - using proxy
+            logger.debug('Listening on port 14555 (proxy)')
+            self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14555', source_system=254)  # type: ignore
        self.connection.target_system = system_id
        self.mavlink: mavlink.MAVLink = self.connection.mav
        self._event_listeners: Dict[str, List[Callable[..., Any]]] = {}
@@ -192,8 +186,7 @@ class Flix:
            self._trigger('motors', self.motors)

        if isinstance(msg, mavlink.MAVLink_scaled_imu_message):
-            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.acc = self._mavlink_to_flu([msg.xacc / 1000, msg.yacc / 1000, msg.zacc / 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)
@@ -1,6 +1,6 @@
 [project]
 name = "pyflix"
-version = "0.16"
+version = "0.11"
 description = "Python API for Flix drone"
 authors = [{ name="Oleg Kalachev", email="okalachev@gmail.com" }]
 license = "MIT"