Add level calibration

Add parameters for IMU orientation definition
2026-06-28 05:56:44 +00:00 · 2025-12-26 11:29:12 +03:00 · 2025-12-26 06:29:19 +03:00
60 changed files with 421 additions and 989 deletions
@@ -23,10 +23,10 @@ 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: Build firmware with WiFi disabled
      run: sed -i 's/^#define WIFI_ENABLED 1$/#define WIFI_ENABLED 0/' flix/flix.ino && make
    - name: Check c_cpp_properties.json
      run: tools/check_c_cpp_properties.py
@@ -7,7 +7,6 @@
 	"MD024": false,
 	"MD033": false,
 	"MD034": false,
 	"MD040": false,
 	"MD059": false,
 	"MD044": {
 		"html_elements": false,
@@ -6,18 +6,19 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/.arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
 				"~/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Arduino/libraries/**",
 				"/usr/include/gazebo-11/",
 				"/usr/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/.arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
+				"~/.arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -30,10 +31,9 @@
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
-				"${workspaceFolder}/flix/parameters.ino",
+				"${workspaceFolder}/flix/parameters.ino"
 				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/.arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -53,18 +53,19 @@
 			"name": "Mac",
 			"includePath": [
 				"${workspaceFolder}/flix",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/Library/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/include/**",
 				"~/Library/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**",
 				"/opt/homebrew/include/gazebo-11/",
 				"/opt/homebrew/include/ignition/math6/"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
+				"~/Library/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/flix.ino",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
@@ -77,10 +78,9 @@
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
-				"${workspaceFolder}/flix/parameters.ino",
+				"${workspaceFolder}/flix/parameters.ino"
 				"${workspaceFolder}/flix/safety.ino"
 			],
-			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2511/bin/xtensa-esp32-elf-g++",
+			"compilerPath": "~/Library/Arduino15/packages/esp32/tools/esp-x32/2411/bin/xtensa-esp32-elf-g++",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -103,16 +103,17 @@
 				"${workspaceFolder}/flix",
 				"${workspaceFolder}/gazebo",
 				"${workspaceFolder}/tools/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/libraries/**",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/libraries/**",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32",
-				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-libs/3.3.6/include/**",
+				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/**",
 				"~/AppData/Local/Arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.4-2f7dcd86-v1/esp32/dio_qspi/include",
 				"~/Documents/Arduino/libraries/**"
 			],
 			"forcedInclude": [
 				"${workspaceFolder}/.vscode/intellisense.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/cores/esp32/Arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/cores/esp32/Arduino.h",
-				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.3.6/variants/d1_mini32/pins_arduino.h",
+				"~/AppData/Local/Arduino15/packages/esp32/hardware/esp32/3.2.0/variants/d1_mini32/pins_arduino.h",
 				"${workspaceFolder}/flix/cli.ino",
 				"${workspaceFolder}/flix/control.ino",
 				"${workspaceFolder}/flix/estimate.ino",
@@ -125,10 +126,9 @@
 				"${workspaceFolder}/flix/rc.ino",
 				"${workspaceFolder}/flix/time.ino",
 				"${workspaceFolder}/flix/wifi.ino",
-				"${workspaceFolder}/flix/parameters.ino",
+				"${workspaceFolder}/flix/parameters.ino"
 				"${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-x32/2411/bin/xtensa-esp32-elf-g++.exe",
 			"cStandard": "c11",
 			"cppStandard": "c++17",
 			"defines": [
@@ -1,5 +1,6 @@
 BOARD = esp32:esp32:d1_mini32
-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 := $(wildcard /dev/serial/by-id/usb-Silicon_Labs_CP21* /dev/serial/by-id/usb-1a86_USB_Single_Serial_* /dev/cu.usbserial-*)
 PORT := $(strip $(PORT))
 build: .dependencies
 	arduino-cli compile --fqbn $(BOARD) flix
@@ -12,16 +13,12 @@ monitor:
 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 core install esp32:esp32@3.2.0 --config-file arduino-cli.yaml
 	arduino-cli lib update-index
 	arduino-cli lib install "FlixPeriph"
-	arduino-cli lib install "MAVLink"@2.0.25
+	arduino-cli lib install "MAVLink"@2.0.16
 	touch .dependencies
 upload_proxy: .dependencies
 	arduino-cli compile --fqbn $(BOARD) tools/espnow-proxy
 	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" tools/espnow-proxy
 gazebo/build cmake: gazebo/CMakeLists.txt
 	mkdir -p gazebo/build
 	cd gazebo/build && cmake ..
@@ -1,9 +1,6 @@
-<!-- markdownlint-disable MD041 -->
+# Flix
-<p align="center">
+**Flix** (*flight + X*) — open source ESP32-based quadcopter made from scratch.
  <img src="docs/img/flix.svg" width=180 alt="Flix logo"><br>
  <b>Flix</b> (<i>flight + X</i>) — open source ESP32-based quadcopter made from scratch.
 </p>
 <table>
  <tr>
@@ -21,13 +18,15 @@
 * 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 using USB gamepad, remote control or smartphone.
-* Control with USB gamepad, remote control or smartphone.
+* Wi-Fi and MAVLink support.
 * Wireless command line interface and analyzing.
 * Precise simulation with Gazebo.
-* Python library for scripting and automatic flights.
+* Python library.
 * Textbook on flight control theory and practice ([in development](https://quadcopter.dev)).
-* *Position control (planned)*.
+* *Position control (using external camera) and autonomous flights¹*.
 *¹ — planned.*
 ## It actually flies
@@ -53,7 +52,7 @@ 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).
@@ -71,14 +70,14 @@ 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|
+|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)<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|
+|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|
+|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).<br>Make sure the battery has enough discharge rate — 25C or more!|<img src="docs/img/battery.jpg" width=100>|1|
+|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|
@@ -138,10 +137,10 @@ You can see a user-contributed [variant of complete circuit diagram](https://mir
  |Motor|Position|Direction|Prop type|Motor wires|GPIO|
  |-|-|-|-|-|-|
-  |Motor 0|Rear left|Counter-clockwise|B|Black & White|GPIO12 *(TDI)*|
+  |Motor 0|Rear left|Counter-clockwise|B|Black & White|GPIO12 (*TDI*)|
-  |Motor 1|Rear right|Clockwise|A|Blue & Red|GPIO13 *(TCK)*|
+  |Motor 1|Rear right|Clockwise|A|Blue & Red|GPIO13 (*TCK*)|
-  |Motor 2|Front right|Counter-clockwise|B|Black & White|GPIO14 *(TMS)*|
+  |Motor 2|Front right|Counter-clockwise|B|Black & White|GPIO14 (*TMS*)|
-  |Motor 3|Front left|Clockwise|A|Blue & Red|GPIO15 *(TD0)*|
+  |Motor 3|Front left|Clockwise|A|Blue & Red|GPIO15 (*TD0*)|
  Clockwise motors have blue & red wires and correspond to propeller type A (marked on the propeller).
  Counter-clockwise motors have black & white wires correspond to propeller type B.
@@ -152,16 +151,14 @@ 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.
 ## 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
@@ -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]
@@ -43,10 +41,10 @@ Motors connection table:
 |Motor|Position|Direction|Prop type|Motor wires|GPIO|
 |-|-|-|-|-|-|
-|Motor 0|Rear left|Counter-clockwise|B|Black & White|GPIO12 *(TDI)*|
+|Motor 0|Rear left|Counter-clockwise|B|Black & White|GPIO12 (*TDI*)|
-|Motor 1|Rear right|Clockwise|A|Blue & Red|GPIO13 *(TCK)*|
+|Motor 1|Rear right|Clockwise|A|Blue & Red|GPIO13 (*TCK*)|
-|Motor 2|Front right|Counter-clockwise|B|Black & White|GPIO14 *(TMS)*|
+|Motor 2|Front right|Counter-clockwise|B|Black & White|GPIO14 (*TMS*)|
-|Motor 3|Front left|Clockwise|A|Blue & Red|GPIO15 *(TD0)*|
+|Motor 3|Front left|Clockwise|A|Blue & Red|GPIO15 (*TD0*)|
 ## Motors tightening
@@ -35,7 +35,7 @@
 ### Подсистема управления
-Состояние органов управления обрабатывается в функции `interpretControls()` и преобразуется в **команду управления**, которая включает следующее:
+Состояние органов управления обрабатывается в функции `interpretControls()` и преобразуется в *команду управления*, которая включает следующее:
 * `attitudeTarget` *(Quaternion)* — целевая ориентация дрона.
 * `ratesTarget` *(Vector)* — целевые угловые скорости, *рад/с*.
@@ -110,7 +110,7 @@ float angle = Vector::angleBetween(a, b); // 1.57 (90 градусов)
 #### Скалярное произведение
-Скалярное произведение векторов *(dot product)* — это произведение длин двух векторов на косинус угла между ними. В математике оно обозначается знаком `·` или слитным написанием векторов. Интуитивно, результат скалярного произведения показывает, насколько два вектора *сонаправлены*.
+Скалярное произведение векторов (*dot product*) — это произведение длин двух векторов на косинус угла между ними. В математике оно обозначается знаком `·` или слитным написанием векторов. Интуитивно, результат скалярного произведения показывает, насколько два вектора *сонаправлены*.
 В Flix используется статический метод `Vector::dot()`:
@@ -124,7 +124,7 @@ float dotProduct = Vector::dot(a, b); // 32
 #### Векторное произведение
-Векторное произведение *(cross product)* позволяет найти вектор, перпендикулярный двум другим векторам. В математике оно обозначается знаком `×`, а в прошивке используется статический метод `Vector::cross()`:
+Векторное произведение (*cross product*) позволяет найти вектор, перпендикулярный двум другим векторам. В математике оно обозначается знаком `×`, а в прошивке используется статический метод `Vector::cross()`:
 ```cpp
 Vector a(1, 2, 3);
@@ -144,9 +144,9 @@ Vector crossProduct = Vector::cross(a, b); // -3, 6, -3
 В прошивке углы Эйлера сохраняются в обычный объект `Vector` (хоть и, строго говоря, не являются вектором):
-* Угол по крену *(roll)* — `vector.x`.
+* Угол по крену (*roll*) — `vector.x`.
-* Угол по тангажу *(pitch)* — `vector.y`.
+* Угол по тангажу (*pitch*) — `vector.y`.
-* Угол по рысканию *(yaw)* — `vector.z`.
+* Угол по рысканию (*yaw*) — `vector.z`.
 Особенности углов Эйлера:
@@ -162,8 +162,8 @@ Vector crossProduct = Vector::cross(a, b); // -3, 6, -3
 Помимо углов Эйлера, любую ориентацию в трехмерном пространстве можно представить в виде вращения вокруг некоторой оси на некоторый угол. В геометрии это доказывается, как **теорема вращения Эйлера**. В таком представлении ориентация задается двумя величинами:
-* **Ось вращения** *(axis)* — единичный вектор, определяющий ось вращения.
+* **Ось вращения** (*axis*) — единичный вектор, определяющий ось вращения.
-* **Угол поворота** *(angle* или *θ)* — угол, на который нужно повернуть объект вокруг этой оси.
+* **Угол поворота** (*angle* или *θ*) — угол, на который нужно повернуть объект вокруг этой оси.
 В Flix ось вращения задается объектом `Vector`, а угол поворота — числом типа `float` в радианах:
@@ -177,7 +177,7 @@ float angle = radians(45);
 ### Вектор вращения
-Если умножить вектор *axis* на угол поворота *θ*, то получится **вектор вращения** *(rotation vector)*. Этот вектор играет важную роль в алгоритмах управления ориентацией летательного аппарата.
+Если умножить вектор *axis* на угол поворота *θ*, то получится **вектор вращения** (*rotation vector*). Этот вектор играет важную роль в алгоритмах управления ориентацией летательного аппарата.
 Вектор вращения обладает замечательным свойством: если угловые скорости объекта (в собственной системе координат) в каждый момент времени совпадают с компонентами этого вектора, то за единичное время объект придет к заданной этим вектором ориентации. Это свойство позволяет использовать вектор вращения для управления ориентацией объекта посредством управления угловыми скоростями.
@@ -198,7 +198,7 @@ Vector rotation = radians(45) * Vector(1, 2, 3);
 	<a href="https://github.com/okalachev/flix/blob/master/flix/quaternion.h"><code>quaternion.h</code></a>.<br>
 </div>
-Вектор вращения удобен, но еще удобнее использовать **кватернион**. В Flix кватернионы задаются объектами `Quaternion` из библиотеки `quaternion.h`. Кватернион состоит из четырех значений: *w*, *x*, *y*, *z* и рассчитывается из вектора оси вращения *(axis)* и угла поворота *(θ)* по формуле:
+Вектор вращения удобен, но еще удобнее использовать **кватернион**. В Flix кватернионы задаются объектами `Quaternion` из библиотеки `quaternion.h`. Кватернион состоит из четырех значений: *w*, *x*, *y*, *z* и рассчитывается из вектора оси вращения (*axis*) и угла поворота (*θ*) по формуле:
 \\[ q = \left( \begin{array}{c} w \\\\ x \\\\ y \\\\ z \end{array} \right) = \left( \begin{array}{c} \cos\left(\frac{\theta}{2}\right) \\\\ axis\_x \cdot \sin\left(\frac{\theta}{2}\right) \\\\ axis\_y \cdot \sin\left(\frac{\theta}{2}\right) \\\\ axis\_z \cdot \sin\left(\frac{\theta}{2}\right) \end{array} \right) \\]
@@ -87,13 +87,13 @@ Flix поддерживает следующие модели IMU:
 #include <FlixPeriph.h>
 #include <SPI.h>
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
 void setup() {
 	Serial.begin(115200);
-	bool success = imu.begin();
+	bool success = IMU.begin();
 	if (!success) {
-		Serial.println("Failed to initialize the IMU");
+		Serial.println("Failed to initialize IMU");
 	}
 }
 ```
@@ -108,21 +108,21 @@ void setup() {
 #include <FlixPeriph.h>
 #include <SPI.h>
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
 void setup() {
 	Serial.begin(115200);
-	bool success = imu.begin();
+	bool success = IMU.begin();
 	if (!success) {
-		Serial.println("Failed to initialize the IMU");
+		Serial.println("Failed to initialize IMU");
 	}
 }
 void loop() {
-	imu.waitForData();
+	IMU.waitForData();
 	float gx, gy, gz;
-	imu.getGyro(gx, gy, gz);
+	IMU.getGyro(gx, gy, gz);
 	Serial.printf("gx:%f gy:%f gz:%f\n", gx, gy, gz);
 	delay(50); // замедление вывода
@@ -135,36 +135,36 @@ void loop() {
 ## Конфигурация гироскопа
-В коде Flix настройка IMU происходит в функции `configureIMU`. В этой функции настраиваются три основных параметра гироскопа: диапазон измерений, частота сэмплирования и частота LPF-фильтра.
+В коде Flix настройка IMU происходит в функции `configureIMU`. В этой функции настраиваются три основных параметра гироскопа: диапазон измерений, частота сэмплов и частота LPF-фильтра.
-### Частота сэмплирования
+### Частота сэмплов
-Большинство IMU могут обновлять данные с разной частотой. В полетных контроллерах обычно используется частота обновления от 500 Гц до 8 кГц. Чем выше частота, тем выше точность управления полетом, но и тем больше нагрузка на микроконтроллер.
+Большинство IMU могут обновлять данные с разной частотой. В полетных контроллерах обычно используется частота обновления от 500 Гц до 8 кГц. Чем выше частота сэмплов, тем выше точность управления полетом, но и больше нагрузка на микроконтроллер.
-Частота сэмплирования устанавливается методом `setSampleRate()`. В Flix используется частота 1 кГц:
+Частота сэмплов устанавливается методом `setSampleRate()`. В Flix используется частота 1 кГц:
 ```cpp
 IMU.setRate(IMU.RATE_1KHZ_APPROX);
 ```
-Поскольку не все поддерживаемые IMU могут работать строго на частоте 1 кГц, в библиотеке FlixPeriph существует возможность приближенной настройки частоты сэмплирования. Например, у IMU ICM-20948 при такой настройке реальная частота сэмплирования будет равна 1125 Гц.
+Поскольку не все поддерживаемые IMU могут работать строго на частоте 1 кГц, в библиотеке FlixPeriph существует возможность приближенной настройки частоты сэмплов. Например, у IMU ICM-20948 при такой настройке реальная частота сэмплирования будет равна 1125 Гц.
 Другие доступные для установки в библиотеке FlixPeriph частоты сэмплирования:
-* `RATE_MIN` — минимальная частота для конкретного IMU.
+* `RATE_MIN` — минимальная частота сэмплов для конкретного IMU.
 * `RATE_50HZ_APPROX` — значение, близкое к 50 Гц.
 * `RATE_1KHZ_APPROX` — значение, близкое к 1 кГц.
 * `RATE_8KHZ_APPROX` — значение, близкое к 8 кГц.
-* `RATE_MAX` — максимальная частота для конкретного IMU.
+* `RATE_MAX` — максимальная частота сэмплов для конкретного IMU.
 #### Диапазон измерений
-Большинство MEMS-гироскопов поддерживают несколько диапазонов измерений угловой скорости. Главное преимущество выбора меньшего диапазона — бо́льшая чувствительность. В полетных контроллерах обычно выбирается максимальный диапазон измерений от –2000 до 2000 градусов в секунду, чтобы обеспечить возможность быстрых маневров.
+Большинство MEMS-гироскопов поддерживают несколько диапазонов измерений угловой скорости. Главное преимущество выбора меньшего диапазона — бо́льшая чувствительность. В полетных контроллерах обычно выбирается максимальный диапазон измерений от –2000 до 2000 градусов в секунду, чтобы обеспечить возможность динамичных маневров.
 В библиотеке FlixPeriph диапазон измерений гироскопа устанавливается методом `setGyroRange()`:
 ```cpp
-imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
+IMU.setGyroRange(IMU.GYRO_RANGE_2000DPS);
 ```
 ### LPF-фильтр
@@ -172,16 +172,16 @@ imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
 IMU InvenSense могут фильтровать измерения на аппаратном уровне при помощи фильтра нижних частот (LPF). Flix реализует собственный фильтр для гироскопа, чтобы иметь больше гибкости при поддержке разных IMU. Поэтому для встроенного LPF устанавливается максимальная частота среза:
 ```cpp
-imu.setDLPF(imu.DLPF_MAX);
+IMU.setDLPF(IMU.DLPF_MAX);
 ```
 ## Калибровка гироскопа
-Как и любое измерительное устройство, гироскоп вносит искажения в измерения. Наиболее простая модель этих искажений делит их на статические смещения *(bias)* и случайный шум *(noise)*:
+Как и любое измерительное устройство, гироскоп вносит искажения в измерения. Наиболее простая модель этих искажений делит их на статические смещения (*bias*) и случайный шум (*noise*):
 \\[ gyro_{xyz}=rates_{xyz}+bias_{xyz}+noise \\]
-Для точной работы подсистемы оценки ориентации и управления дроном необходимо оценить *bias* гироскопа и учесть его в вычислениях. Для этого при запуске программы производится калибровка гироскопа, которая реализована в функции `calibrateGyro()`. Эта функция считывает данные с гироскопа в состоянии покоя 1000 раз и усредняет их. Полученные значения считаются *bias* гироскопа и в дальнейшем вычитаются из измерений.
+Для качественной работы подсистемы оценки ориентации и управления дроном необходимо оценить *bias* гироскопа и учесть его в вычислениях. Для этого при запуске программы производится калибровка гироскопа, которая реализована в функции `calibrateGyro()`. Эта функция считывает данные с гироскопа в состоянии покоя 1000 раз и усредняет их. Полученные значения считаются *bias* гироскопа и в дальнейшем вычитаются из измерений.
 Программа для вывода данных с гироскопа с калибровкой:
@@ -189,23 +189,23 @@ imu.setDLPF(imu.DLPF_MAX);
 #include <FlixPeriph.h>
 #include <SPI.h>
-MPU9250 imu(SPI);
+MPU9250 IMU(SPI);
 float gyroBiasX, gyroBiasY, gyroBiasZ; // bias гироскопа
 void setup() {
 	Serial.begin(115200);
-	bool success = imu.begin();
+	bool success = IMU.begin();
 	if (!success) {
-		Serial.println("Failed to initialize the IMU");
+		Serial.println("Failed to initialize IMU");
 	}
 	calibrateGyro();
 }
 void loop() {
 	float gx, gy, gz;
-	imu.waitForData();
+	IMU.waitForData();
-	imu.getGyro(gx, gy, gz);
+	IMU.getGyro(gx, gy, gz);
 	// Устранение bias гироскопа
 	gx -= gyroBiasX;
@@ -226,9 +226,9 @@ void calibrateGyro() {
 	// Получение 1000 измерений гироскопа
 	for (int i = 0; i < samples; i++) {
-		imu.waitForData();
+		IMU.waitForData();
 		float gx, gy, gz;
-		imu.getGyro(gx, gy, gz);
+		IMU.getGyro(gx, gy, gz);
 		gyroBiasX += gx;
 		gyroBiasY += gy;
 		gyroBiasZ += gz;
@@ -38,13 +38,13 @@ Utility files:
 ### Control subsystem
-Pilot inputs are interpreted in `interpretControls()`, and then converted to the **control command**, which consists of the following:
+Pilot inputs are interpreted in `interpretControls()`, and then converted to the *control command*, which consists of the following:
 * `attitudeTarget` *(Quaternion)* — target attitude of the drone.
 * `ratesTarget` *(Vector)* — target angular rates, *rad/s*.
-* `ratesExtra` *(Vector)* — additional (feed-forward) angular rates, used for yaw rate control in STAB mode, *rad/s*.
+* `ratesExtra` *(Vector)* — additional (feed-forward) angular rates , used for yaw rate control in STAB mode, *rad/s*.
 * `torqueTarget` *(Vector)* — target torque, range [-1, 1].
-* `thrustTarget` *(float)* — collective motor thrust target, range [0, 1].
+* `thrustTarget` *(float)* — collective thrust target, range [0, 1].
 Control command is handled in `controlAttitude()`, `controlRates()`, `controlTorque()` functions. Each function may be skipped if the corresponding control target is set to `NAN`.
@@ -62,40 +62,6 @@ print("Test value: %.2f\n", testValue);
 In order to add a console command, modify the `doCommand()` function in `cli.ino` file.
 > [!IMPORTANT]
 > Avoid using delays in in-flight commands, it will **crash** the drone! (The design is one-threaded.)
 >
 > 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).
 ## 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).
@@ -1,38 +0,0 @@
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@@ -4,7 +4,7 @@
 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 ESP32 core is installed**. Check if the version matches the one used in the [tutorial](usage.md#firmware).
 * **Check libraries**. Install all the required libraries from the tutorial. Make sure there are no MPU9250 or other peripherals libraries that may conflict with the ones used in the tutorial.
 * **Check the chosen board**. The correct board to choose in Arduino IDE for ESP32 Mini is *WEMOS D1 MINI ESP32*.
@@ -12,25 +12,20 @@ Do the following:
 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 voltage**. Use a multimeter to measure the battery voltage. It should be in range of 3.7-4.2 V.
-* **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 to make sure you see the whole ESP32 output.
 * **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.
-* **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)*.
+* **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 CLI is working**. Perform `help` command in Serial Monitor. You should see the list of available commands. You can also access the CLI using QGroundControl (*Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*).
 * **Configure QGroundControl correctly before connecting to the drone** if you use it to control the drone. Go to the settings and enable *Virtual Joystick*. *Auto-Center Throttle* setting **should be disabled**.
 * **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:
+* **Check the attitude estimation**. Connect to the drone using QGroundControl. Rotate the drone in different orientations and check if the attitude estimation shown in QGroundControl is correct.
-
+* **Check the IMU orientation is set correctly**. If the attitude estimation is rotated, make sure `rotateIMU` function is defined correctly in `imu.ino` file.
  <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).
@@ -38,10 +33,7 @@ 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 an SBUS receiver**:
+* If using SBUS receiver, **calibrate the RC**. Type `cr` command in Serial Monitor and follow the instructions.
-  * **Define the used GPIO pin** in `RC_RX_PIN` parameter.
+* **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.
  * **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.
@@ -20,10 +20,10 @@ 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 3.3.6. 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 3.2.0. See the [official Espressif's instructions](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-arduino-ide) on installing ESP32 Core in Arduino IDE.
 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.
+   * `MAVLink`, version 2.0.16.
 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. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
@@ -80,7 +80,7 @@ QGroundControl is a ground control station software that can be used to monitor
 1. Install mobile or desktop version of [QGroundControl](https://docs.qgroundcontrol.com/master/en/qgc-user-guide/getting_started/download_and_install.html).
 2. Power up the drone.
 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.
+4. Launch QGroundControl app. It should connect and begin showing the drone's telemetry automatically
 ### Access console
@@ -108,13 +108,11 @@ The drone is configured using parameters. To access and modify them, go to the Q
 <img src="img/parameters.png" width="400">
 You can also work with parameters using `p` command in the console. Parameter names are case-insensitive.
 ### 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 side with the components:
 <img src="img/imu-axes.png" width="200">
@@ -122,10 +120,10 @@ 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-1.png" width="200">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 0    |<img src="img/imu-rot-5.png" width="200">|`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="200">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|<img src="img/imu-rot-6.png" width="200">|`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-3.png" width="200">|`IMU_ROT_ROLL` = 0<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 3.142|<img src="img/imu-rot-7.png" width="200">|`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="200"><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="200">|`IMU_ROT_ROLL` = 3.142<br>`IMU_ROT_PITCH` = 0<br>`IMU_ROT_YAW` = 1.571|
 ### Calibrate accelerometer
@@ -134,54 +132,25 @@ Before flight you need to calibrate the accelerometer:
 1. Access the console using QGroundControl (recommended) or Serial Monitor.
 2. Type `ca` command there and follow the instructions.
-### Setup motors
+### Check everything works
-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).
+1. Check the IMU is working: perform `imu` command and check its output:
 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).
 2. Decrease the PWM frequency using the `MOT_PWM_FREQ` parameter (400 is typical).
 > [!CAUTION]
 > **Remove the props when configuring the motors!** If improperly configured, you may not be able to stop them.
 ### Battery voltage monitoring
 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:
+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. Attitude indicator in QGroundControl is shown below:
-   <a href="https://youtu.be/yVRN23-GISU"><img width=300 src="https://i3.ytimg.com/vi/yVRN23-GISU/maxresdefault.jpg"></a>
+   <img src="img/qgc-attitude.png" height="200">
-3. Perform motor tests. Use the following commands **— remove the propellers before running the tests!**
+3. Perform motor tests in the console. Use the following commands **— remove the propellers before running the tests!**
-   * `mfr` — rotate front right motor (counter-clockwise).
+   * `mfr` — should rotate front right motor (counter-clockwise).
-   * `mfl` — rotate front left motor (clockwise).
+   * `mfl` — should rotate front left motor (clockwise).
-   * `mrl` — rotate rear left motor (counter-clockwise).
+   * `mrl` — should rotate rear left motor (counter-clockwise).
-   * `mrr` — rotate rear right motor (clockwise).
+   * `mrr` — should rotate rear right motor (clockwise).
   Make sure rotation directions and propeller types match the following diagram:
   <img src="img/motors.svg" width=200>
 > [!WARNING]
 > Never run the motors when powering the drone from USB, always use the battery for that.
@@ -190,19 +159,7 @@ After this setup, you should see the battery voltage in QGroundControl top panel
 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).
-### Control with a smartphone
+### Control with 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.
@@ -214,17 +171,15 @@ There are several ways to control the drone's flight: using **smartphone** (Wi-F
 > [!TIP]
 > Decrease `CTL_TILT_MAX` parameter when flying using the smartphone to make the controls less sensitive.
-### Control with a remote control
+### Control with remote control
-If using SBUS-connected remote control you need to enable SBUS and calibrate it:
+Before using remote SBUS-connected remote control, you need to calibrate it:
-1. Connect to the drone using QGroundControl.
+1. Access the console using QGroundControl (recommended) or Serial Monitor.
-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.
+2. Type `cr` command and follow the instructions.
-3. Check if the receiver is working using `rc` command in the console.
+3. Use the remote control to fly the drone!
 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
+### Control with USB remote control
 If your drone doesn't have RC receiver installed, you can use USB remote control and QGroundControl app to fly it.
@@ -259,11 +214,11 @@ 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 (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 or using the command line.
 #### 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.
+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.
 > [!IMPORTANT]
 > The drone doesn't stabilize its position, so slight drift is possible. The pilot should compensate it manually.
@@ -278,75 +233,15 @@ 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). The drone can be controlled using [pyflix](../tools/pyflix/) Python library, or by modifying the firmware to implement the needed behavior.
+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.
-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
+<img src="img/parameters.png" width="400">
 You can configure the Wi-Fi using parameters and console commands.
 The Wi-Fi mode is chosen using `WIFI_MODE` parameter in QGroundControl or in the console:
 * `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.
 The SSID and password are configured using the `ap` and `sta` console commands:
 ```
 ap <ssid> <password>
 sta <ssid> <password>
 ```
 Example of configuring the Access Point mode:
 ```
 ap my-flix-ssid mypassword123
 p WIFI_MODE 1
 ```
 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.
 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:
+After the flight, you can download the flight log for analysis wirelessly. Use the following for that:
 ```bash
 make log
@@ -4,49 +4,6 @@ This page contains user-built drones based on the Flix project. Publish your pro
 ---
 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>
@@ -59,7 +16,7 @@ Author: [goldarte](https://t.me/goldarte).<br>
 ## 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.
+Special quadcopter design and engineering course took place in october-november 2025 in School 548, Moscow. Course included UAV control theory, electronics, and practical drone assembly and setup using the Flix project.
 <img height=200 src="img/user/school548/1.jpg"> <img height=200 src="img/user/school548/2.jpg"> <img height=200 src="img/user/school548/3.jpg">
@@ -68,7 +25,7 @@ STL files and other materials: see [here](https://drive.google.com/drive/folders
 ### Selected works
 Author: [KiraFlux](https://t.me/@kiraflux_0XC0000005).<br>
-Description: **custom ESPNOW remote control** was implemented, modified firmware to support ESPNOW protocol.<br>
+Description: **custom ESPNOW remote control** is implemented, firmware modified to support ESPNOW protocol.<br>
 Telegram posts: [1](https://t.me/opensourcequadcopter/106), [2](https://t.me/opensourcequadcopter/114).<br>
 Modified Flix firmware: https://github.com/KiraFlux/flix/tree/klyax.<br>
 Remote control project: https://github.com/KiraFlux/ESP32-DJC.<br>
@@ -6,28 +6,23 @@
 #include "pid.h"
 #include "vector.h"
 #include "util.h"
 #include "lpf.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 float controlRoll, controlPitch, controlThrottle, controlYaw, controlMode;
 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"
@@ -42,15 +37,12 @@ const char* motd =
 "disarm - disarm the drone\n"
 "raw/stab/acro/auto - set mode\n"
 "rc - show RC data\n"
 "pw - show power info\n"
 "wifi - show Wi-Fi info\n"
 "ap <ssid> <password> - setup Wi-Fi access point\n"
 "sta <ssid> <password> - setup Wi-Fi client mode\n"
 "espnow <mac> [<key>] - setup ESP-NOW peer\n"
 "mot - show motor output\n"
 "log [dump] - print log header [and data]\n"
 "cr - calibrate RC\n"
 "ca - calibrate accel\n"
 "cl - calibrate level\n"
 "mfr, mfl, mrr, mrl - test motor (remove props)\n"
 "sys - show system info\n"
 "reset - reset drone's state\n"
@@ -63,7 +55,9 @@ void print(const char* format, ...) {
 	vsnprintf(buf, sizeof(buf), format, args);
 	va_end(args);
 	Serial.print(buf);
 #if WIFI_ENABLED
 	mavlinkPrint(buf);
 #endif
 }
 void pause(float duration) {
@@ -71,7 +65,9 @@ void pause(float duration) {
 	while (t - start < duration) {
 		step();
 		handleInput();
 #if WIFI_ENABLED
 		processMavlink();
 #endif
 		delay(50);
 	}
 }
@@ -99,7 +95,7 @@ void doCommand(String str, bool echo = false) {
 	} else if (command == "p") {
 		bool success = setParameter(arg0.c_str(), arg1.toFloat());
 		if (success) {
-			print("%s = %g\n", arg0.c_str(), getParameter(arg0.c_str()));
+			print("%s = %g\n", arg0.c_str(), arg1.toFloat());
 		} else {
 			print("Parameter not found: %s\n", arg0.c_str());
 		}
@@ -137,19 +133,12 @@ void doCommand(String str, bool echo = false) {
 		}
 		print("\nroll: %g pitch: %g yaw: %g throttle: %g mode: %g\n",
 			controlRoll, controlPitch, controlYaw, controlThrottle, controlMode);
 		print("time: %.1f\n", controlTime);
 		print("mode: %s\n", getModeName());
 		print("armed: %d\n", armed);
 	} else if (command == "pw") {
 		print("Voltage: %.1f V\n", voltage);
 	} else if (command == "wifi") {
 #if WIFI_ENABLED
 		printWiFiInfo();
-	} else if (command == "ap") {
+#endif
 		configWiFi(W_AP, 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());
 	} 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]);
@@ -160,6 +149,8 @@ void doCommand(String str, bool echo = false) {
 		calibrateRC();
 	} else if (command == "ca") {
 		calibrateAccel();
 	} else if (command == "cl") {
 		calibrateLevel();
 	} else if (command == "mfr") {
 		testMotor(MOTOR_FRONT_RIGHT);
 	} else if (command == "mfl") {
@@ -173,7 +164,6 @@ void doCommand(String str, bool echo = false) {
 		print("Chip: %s\n", ESP.getChipModel());
 		print("Temperature: %.1f °C\n", temperatureRead());
 		print("Free heap: %d\n", ESP.getFreeHeap());
 		print("Firmware: " __DATE__ " " __TIME__ "\n");
 		// Print tasks table
 		print("Num  Task                Stack  Prio  Core  CPU%%\n");
 		int taskCount = uxTaskGetNumberOfTasks();
@@ -184,13 +174,12 @@ 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
 	} else if (command == "reset") {
 		attitude = Quaternion();
 		gyroBiasFilter.reset();
 	} else if (command == "reboot") {
 		ESP.restart();
 	} else {
@@ -38,12 +38,6 @@ const int RAW = 0, ACRO = 1, STAB = 2, AUTO = 3; // flight modes
 int mode = STAB;
 bool armed = false;
 Quaternion attitudeTarget;
 Vector ratesTarget;
 Vector ratesExtra; // feedforward rates
 Vector torqueTarget;
 float thrustTarget;
 PID rollRatePID(ROLLRATE_P, ROLLRATE_I, ROLLRATE_D, ROLLRATE_I_LIM, RATES_D_LPF_ALPHA);
 PID pitchRatePID(PITCHRATE_P, PITCHRATE_I, PITCHRATE_D, PITCHRATE_I_LIM, RATES_D_LPF_ALPHA);
 PID yawRatePID(YAWRATE_P, YAWRATE_I, YAWRATE_D);
@@ -52,7 +46,12 @@ PID pitchPID(PITCH_P, PITCH_I, PITCH_D);
 PID yawPID(YAW_P, 0, 0);
 Vector maxRate(ROLLRATE_MAX, PITCHRATE_MAX, YAWRATE_MAX);
 float tiltMax = TILT_MAX;
-int flightModes[] = {STAB, STAB, STAB}; // map for rc mode switch
+
 Quaternion attitudeTarget;
 Vector ratesTarget;
 Vector ratesExtra; // feedforward rates
 Vector torqueTarget;
 float thrustTarget;
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
 extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlMode;
@@ -66,9 +65,9 @@ void control() {
 }
 void interpretControls() {
-	if (controlMode < 0.25) mode = flightModes[0];
+	if (controlMode < 0.25) 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 (controlMode > 0.75) mode = STAB;
 	if (mode == AUTO) return; // pilot is not effective in AUTO mode
@@ -149,25 +148,12 @@ void controlTorque() {
 	motors[MOTOR_REAR_LEFT] = thrustTarget + torqueTarget.x + torqueTarget.y - torqueTarget.z;
 	motors[MOTOR_REAR_RIGHT] = thrustTarget - torqueTarget.x + torqueTarget.y + torqueTarget.z;
 	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";
@@ -1,25 +1,19 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
-// Attitude estimation using gyro and accelerometer
+// Attitude estimation from gyro and accelerometer
 #include "quaternion.h"
 #include "vector.h"
 #include "lpf.h"
 #include "util.h"
 Vector rates; // estimated angular rates, rad/s
 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() {
@@ -44,12 +38,3 @@ void applyAcc() {
 	// apply correction
 	attitude = Quaternion::rotate(attitude, Quaternion::fromRotationVector(correction));
 }
 void applyLevel() {
 	if (landed) return;
 	// 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));
 }
@@ -7,23 +7,30 @@
 #include "quaternion.h"
 #include "util.h"
-extern float t, dt;
+#define WIFI_ENABLED 1
-extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
+
-extern Vector gyro, acc;
+float t = NAN; // current step time, s
-extern Vector rates;
+float dt; // time delta from previous step, s
-extern Quaternion attitude;
+float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
-extern bool landed;
+float controlMode = NAN;
-extern float motors[4];
+Vector gyro; // gyroscope data
 Vector acc; // accelerometer data, m/s/s
 Vector rates; // filtered angular rates, rad/s
 Quaternion attitude; // estimated attitude
 bool landed; // are we landed and stationary
 float motors[4]; // normalized motors thrust in range [0..1]
 void setup() {
 	Serial.begin(115200);
 	print("Initializing flix\n");
 	disableBrownOut();
 	setupParameters();
 	setupPower();
 	setupLED();
 	setLED(true);
 	setupMotors();
 	setLED(true);
 #if WIFI_ENABLED
 	setupWiFi();
 #endif
 	setupIMU();
 	setupRC();
 	setLED(false);
@@ -38,8 +45,9 @@ void loop() {
 	control();
 	sendMotors();
 	handleInput();
 #if WIFI_ENABLED
 	processMavlink();
-	readVoltage();
+#endif
 	logData();
 	syncParameters();
 }
@@ -10,16 +10,11 @@
 #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;
 Vector acc; // accelerometer output, m/s/s
 Vector accBias;
 Vector accScale(1, 1, 1);
-
+Vector gyroBias;
 LowPassFilter<Vector> gyroBiasFilter(0.001);
 void setupIMU() {
 	print("Setup IMU\n");
@@ -52,6 +47,8 @@ void readIMU() {
 void calibrateGyroOnce() {
 	static Delay landedDelay(2);
 	if (!landedDelay.update(landed)) return; // calibrate only if definitely stationary
 	static LowPassFilter<Vector> gyroBiasFilter(0.001);
 	gyroBias = gyroBiasFilter.update(gyro);
 }
@@ -110,6 +107,14 @@ void calibrateAccelOnce() {
 	accBias = (accMax + accMin) / 2;
 }
 void calibrateLevel() {
 	print("Place perfectly level [1 sec]\n");
 	pause(1);
 	Quaternion correction = Quaternion::fromBetweenVectors(Quaternion::rotateVector(Vector(0, 0, 1), attitude), Vector(0, 0, 1));
 	imuRotation = Quaternion::rotate(correction, Quaternion::fromEuler(imuRotation)).toEuler();
 	print("✓ Done: %.3f %.3f %.3f\n", degrees(imuRotation.x), degrees(imuRotation.y), degrees(imuRotation.z));
 }
 void printIMUCalibration() {
 	print("gyro bias: %f %f %f\n", gyroBias.x, gyroBias.y, gyroBias.z);
 	print("accel bias: %f %f %f\n", accBias.x, accBias.y, accBias.z);
@@ -121,7 +126,7 @@ void printIMUInfo() {
 	print("model: %s\n", imu.getModel());
 	print("who am I: 0x%02X\n", imu.whoAmI());
 	print("rate: %.0f\n", loopRate);
-	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 +14,15 @@ public:
 	LowPassFilter(float alpha): alpha(alpha) {};
 	T update(const T input) {
-		if (!init) {
+		if (alpha == 1) { // filter disabled
-			init = true;
+			return input;
 			return output = input;
 		}
 		if (!initialized) {
 			output = input;
 			initialized = true;
 		}
 		return output += alpha * (input - output);
 	}
@@ -26,9 +31,9 @@ public:
 	}
 	void reset() {
-		init = false;
+		initialized = false;
 	}
 private:
-	bool init = false;
+	bool initialized = false;
 };
@@ -3,19 +3,21 @@
 // MAVLink communication
 #if WIFI_ENABLED
 #include <MAVLink.h>
 #include "util.h"
-extern float controlTime;
+#define SYSTEM_ID 1
-extern float voltage;
+#define MAVLINK_RATE_SLOW 1
-
+#define MAVLINK_RATE_FAST 10
 int mavlinkSysId = 1;
 Rate telemetryFast(10);
 Rate telemetrySlow(2);
 bool mavlinkConnected = false;
 String mavlinkPrintBuffer;
 extern float controlTime;
 extern float controlRoll, controlPitch, controlThrottle, controlYaw, controlMode;
 void processMavlink() {
 	sendMavlink();
 	receiveMavlink();
@@ -27,8 +29,10 @@ void sendMavlink() {
 	mavlink_message_t msg;
 	uint32_t time = t * 1000;
-	if (telemetrySlow) {
+	static Rate slow(MAVLINK_RATE_SLOW), fast(MAVLINK_RATE_FAST);
-		mavlink_msg_heartbeat_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
+
 	if (slow) {
 		mavlink_msg_heartbeat_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, MAV_TYPE_QUADROTOR, MAV_AUTOPILOT_GENERIC,
 			(armed ? MAV_MODE_FLAG_SAFETY_ARMED : 0) |
 			((mode == STAB) ? MAV_MODE_FLAG_STABILIZE_ENABLED : 0) |
 			((mode == AUTO) ? MAV_MODE_FLAG_AUTO_ENABLED : MAV_MODE_FLAG_MANUAL_INPUT_ENABLED),
@@ -37,35 +41,28 @@ void sendMavlink() {
 		if (!mavlinkConnected) return; // send only heartbeat until connected
-		mavlink_msg_extended_sys_state_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_extended_sys_state_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			MAV_VTOL_STATE_UNDEFINED, landed ? MAV_LANDED_STATE_ON_GROUND : MAV_LANDED_STATE_IN_AIR);
 		sendMessage(&msg);
 		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,
 			MAV_BATTERY_TYPE_LIPO, INT16_MAX, voltages, -1, -1, -1, remaining * 100, 0, MAV_BATTERY_CHARGE_STATE_OK, voltagesExt, 0, 0);
 		if (valid(voltage)) sendMessage(&msg);
 	}
-	if (telemetryFast && mavlinkConnected) {
+	if (fast && mavlinkConnected) {
-		const float offset[] = {0, 0, 0, 0};
+		const float zeroQuat[] = {0, 0, 0, 0};
-		mavlink_msg_attitude_quaternion_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_attitude_quaternion_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
-			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, offset); // convert to frd
+			time, attitude.w, attitude.x, -attitude.y, -attitude.z, rates.x, -rates.y, -rates.z, zeroQuat); // convert to frd
 		sendMessage(&msg);
-		mavlink_msg_rc_channels_raw_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, controlTime * 1000, 0,
+		mavlink_msg_rc_channels_raw_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, controlTime * 1000, 0,
 			channels[0], channels[1], channels[2], channels[3], channels[4], channels[5], channels[6], channels[7], UINT8_MAX);
 		if (channels[0] != 0) sendMessage(&msg); // 0 means no RC input
 		float controls[8];
 		memcpy(controls, motors, sizeof(motors));
-		mavlink_msg_actuator_control_target_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time, 0, controls);
+		mavlink_msg_actuator_control_target_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, time, 0, controls);
 		sendMessage(&msg);
-		mavlink_msg_scaled_imu_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, time,
+		mavlink_msg_scaled_imu_pack(SYSTEM_ID, 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);
@@ -99,7 +96,7 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_MANUAL_CONTROL) {
 		mavlink_manual_control_t m;
 		mavlink_msg_manual_control_decode(&msg, &m);
-		if (m.target && m.target != mavlinkSysId) return; // 0 is broadcast
+		if (m.target && m.target != SYSTEM_ID) return; // 0 is broadcast
 		controlThrottle = m.z / 1000.0f;
 		controlPitch = m.x / 1000.0f;
@@ -112,11 +109,11 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_PARAM_REQUEST_LIST) {
 		mavlink_param_request_list_t m;
 		mavlink_msg_param_request_list_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		mavlink_message_t msg;
 		for (int i = 0; i < parametersCount(); i++) {
-			mavlink_msg_param_value_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+			mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 				getParameterName(i), getParameter(i), MAV_PARAM_TYPE_REAL32, parametersCount(), i);
 			sendMessage(&msg);
 		}
@@ -125,7 +122,7 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_PARAM_REQUEST_READ) {
 		mavlink_param_request_read_t m;
 		mavlink_msg_param_request_read_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		char name[MAVLINK_MSG_PARAM_REQUEST_READ_FIELD_PARAM_ID_LEN + 1];
 		strlcpy(name, m.param_id, sizeof(name)); // param_id might be not null-terminated
@@ -134,7 +131,7 @@ void handleMavlink(const void *_msg) {
 			memcpy(name, getParameterName(m.param_index), 16);
 		}
 		mavlink_message_t msg;
-		mavlink_msg_param_value_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			name, value, MAV_PARAM_TYPE_REAL32, parametersCount(), m.param_index);
 		sendMessage(&msg);
 	}
@@ -142,33 +139,32 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_PARAM_SET) {
 		mavlink_param_set_t m;
 		mavlink_msg_param_set_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		char name[MAVLINK_MSG_PARAM_SET_FIELD_PARAM_ID_LEN + 1];
 		strlcpy(name, m.param_id, sizeof(name)); // param_id might be not null-terminated
-		bool success = setParameter(name, m.param_value);
+		setParameter(name, m.param_value);
 		if (!success) return;
 		// send ack
 		mavlink_message_t msg;
-		mavlink_msg_param_value_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_param_value_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
-			m.param_id, getParameter(name), MAV_PARAM_TYPE_REAL32, parametersCount(), 0); // index is unknown
+			m.param_id, m.param_value, MAV_PARAM_TYPE_REAL32, parametersCount(), 0); // index is unknown
 		sendMessage(&msg);
 	}
 	if (msg.msgid == MAVLINK_MSG_ID_MISSION_REQUEST_LIST) { // handle to make qgc happy
 		mavlink_mission_request_list_t m;
 		mavlink_msg_mission_request_list_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		mavlink_message_t msg;
-		mavlink_msg_mission_count_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, 0, 0, MAV_MISSION_TYPE_MISSION, 0);
+		mavlink_msg_mission_count_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, 0, 0, 0, MAV_MISSION_TYPE_MISSION, 0);
 		sendMessage(&msg);
 	}
 	if (msg.msgid == MAVLINK_MSG_ID_SERIAL_CONTROL) {
 		mavlink_serial_control_t m;
 		mavlink_msg_serial_control_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		char data[MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN + 1];
 		strlcpy(data, (const char *)m.data, m.count); // data might be not null-terminated
@@ -180,7 +176,7 @@ void handleMavlink(const void *_msg) {
 		mavlink_set_attitude_target_t m;
 		mavlink_msg_set_attitude_target_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		// copy attitude, rates and thrust targets
 		ratesTarget.x = m.body_roll_rate;
@@ -202,7 +198,7 @@ void handleMavlink(const void *_msg) {
 		mavlink_set_actuator_control_target_t m;
 		mavlink_msg_set_actuator_control_target_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		attitudeTarget.invalidate();
 		ratesTarget.invalidate();
@@ -214,12 +210,12 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_LOG_REQUEST_DATA) {
 		mavlink_log_request_data_t m;
 		mavlink_msg_log_request_data_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		// Send all log records
 		for (int i = 0; i < sizeof(logBuffer) / sizeof(logBuffer[0]); i++) {
 			mavlink_message_t msg;
-			mavlink_msg_log_data_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, i,
+			mavlink_msg_log_data_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg, 0, i,
 				sizeof(logBuffer[0]), (uint8_t *)logBuffer[i]);
 			sendMessage(&msg);
 		}
@@ -229,13 +225,13 @@ void handleMavlink(const void *_msg) {
 	if (msg.msgid == MAVLINK_MSG_ID_COMMAND_LONG) {
 		mavlink_command_long_t m;
 		mavlink_msg_command_long_decode(&msg, &m);
-		if (m.target_system && m.target_system != mavlinkSysId) return;
+		if (m.target_system && m.target_system != SYSTEM_ID) return;
 		mavlink_message_t response;
 		bool accepted = false;
 		if (m.command == MAV_CMD_REQUEST_MESSAGE && m.param1 == MAVLINK_MSG_ID_AUTOPILOT_VERSION) {
 			accepted = true;
-			mavlink_msg_autopilot_version_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &response,
+			mavlink_msg_autopilot_version_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &response,
 				MAV_PROTOCOL_CAPABILITY_PARAM_FLOAT | MAV_PROTOCOL_CAPABILITY_MAVLINK2, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0);
 			sendMessage(&response);
 		}
@@ -254,7 +250,7 @@ void handleMavlink(const void *_msg) {
 		// send command ack
 		mavlink_message_t ack;
-		mavlink_msg_command_ack_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, accepted ? MAV_RESULT_ACCEPTED : MAV_RESULT_UNSUPPORTED, UINT8_MAX, 0, msg.sysid, msg.compid);
+		mavlink_msg_command_ack_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &ack, m.command, accepted ? MAV_RESULT_ACCEPTED : MAV_RESULT_UNSUPPORTED, UINT8_MAX, 0, msg.sysid, msg.compid);
 		sendMessage(&ack);
 	}
 }
@@ -271,7 +267,7 @@ void sendMavlinkPrint() {
 		char data[MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN + 1];
 		strlcpy(data, str + i, sizeof(data));
 		mavlink_message_t msg;
-		mavlink_msg_serial_control_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
+		mavlink_msg_serial_control_pack(SYSTEM_ID, MAV_COMP_ID_AUTOPILOT1, &msg,
 			SERIAL_CONTROL_DEV_SHELL,
 			i + MAVLINK_MSG_SERIAL_CONTROL_FIELD_DATA_LEN < strlen(str) ? SERIAL_CONTROL_FLAG_MULTI : 0, // more chunks to go
 			0, 0, strlen(data), (uint8_t *)data, 0, 0);
@@ -279,3 +275,5 @@ void sendMavlinkPrint() {
 	}
 	mavlinkPrintBuffer.clear();
 }
 #endif
@@ -1,19 +1,23 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
-// PWM control for motors
+// Motors output control using MOSFETs
 // In case of using ESCs, change PWM_STOP, PWM_MIN and PWM_MAX to appropriate values in μs, decrease PWM_FREQUENCY (to 400)
 #include "util.h"
-float motors[4]; // normalized motor thrusts in range [0..1]
+#define MOTOR_0_PIN 12 // rear left
 #define MOTOR_1_PIN 13 // rear right
 #define MOTOR_2_PIN 14 // front right
 #define MOTOR_3_PIN 15 // front left
-int motorPins[4] = {12, 13, 14, 15}; // default pin numbers
+#define PWM_FREQUENCY 78000
-int pwmFrequency = 78000;
+#define PWM_RESOLUTION 10
-int pwmResolution = 10;
+#define PWM_STOP 0
-int pwmStop = 0;
+#define PWM_MIN 0
-int pwmMin = 0;
+#define PWM_MAX 1000000 / PWM_FREQUENCY
 int pwmMax = -1; // -1 means duty cycle mode
 // Motors array indexes:
 const int MOTOR_REAR_LEFT = 0;
 const int MOTOR_REAR_RIGHT = 1;
 const int MOTOR_FRONT_RIGHT = 2;
@@ -21,31 +25,30 @@ const int MOTOR_FRONT_LEFT = 3;
 void setupMotors() {
 	print("Setup Motors\n");
 	// configure pins
-	for (int i = 0; i < 4; i++) {
+	ledcAttach(MOTOR_0_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
-		ledcAttach(motorPins[i], pwmFrequency, pwmResolution);
+	ledcAttach(MOTOR_1_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
-		pwmFrequency = ledcChangeFrequency(motorPins[i], pwmFrequency, pwmResolution); // when reconfiguring
+	ledcAttach(MOTOR_2_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
-	}
+	ledcAttach(MOTOR_3_PIN, PWM_FREQUENCY, PWM_RESOLUTION);
 	sendMotors();
 	print("Motors initialized\n");
 }
 void sendMotors() {
 	for (int i = 0; i < 4; i++) {
 		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, PWM_MIN, PWM_MAX);
-		float pwm = mapf(value, 0, 1, pwmMin, pwmMax);
+	if (value == 0) pwm = PWM_STOP;
-		if (value == 0) pwm = pwmStop;
+	float duty = mapf(pwm, 0, 1000000 / PWM_FREQUENCY, 0, (1 << PWM_RESOLUTION) - 1);
-		float duty = mapf(pwm, 0, 1000000 / pwmFrequency, 0, (1 << pwmResolution) - 1);
+	return round(duty);
-		return round(duty);
+}
-	} else { // duty cycle mode
+
-		return round(value * ((1 << pwmResolution) - 1));
+void sendMotors() {
-	}
+	ledcWrite(MOTOR_0_PIN, getDutyCycle(motors[0]));
 	ledcWrite(MOTOR_1_PIN, getDutyCycle(motors[1]));
 	ledcWrite(MOTOR_2_PIN, getDutyCycle(motors[2]));
 	ledcWrite(MOTOR_3_PIN, getDutyCycle(motors[3]));
 }
 bool motorsActive() {
@@ -54,7 +57,7 @@ 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);
@@ -6,28 +6,16 @@
 #include <Preferences.h>
 #include "util.h"
-extern int channelZero[16];
+extern float channelZero[16];
-extern int 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;
 extern int wifiMode, wifiLongRange, udpLocalPort, udpRemotePort, espnowChannel;
 extern float rcLossTimeout, descendTime;
 extern int voltagePin;
 extern float voltageScale;
 extern LowPassFilter<float> voltageFilter;
 Preferences storage;
 struct Parameter {
-	const char *name; // max length is 15
+	const char *name; // max length is 15 (Preferences key limit)
-	bool integer;
+	float *variable;
-	union { float *f; int *i; }; // pointer to the variable
+	float value; // cache
 	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) {};
 	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; };
 };
 Parameter parameters[] = {
@@ -36,16 +24,13 @@ 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},
@@ -57,9 +42,6 @@ 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_ROT_ROLL", &imuRotation.x},
 	{"IMU_ROT_PITCH", &imuRotation.y},
@@ -70,23 +52,10 @@ Parameter parameters[] = {
 	{"IMU_ACC_SCALE_X", &accScale.x},
 	{"IMU_ACC_SCALE_Y", &accScale.y},
 	{"IMU_ACC_SCALE_Z", &accScale.z},
 	{"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},
 	{"MOT_PIN_FR", &motorPins[MOTOR_FRONT_RIGHT], setupMotors},
 	{"MOT_PIN_RL", &motorPins[MOTOR_REAR_LEFT], setupMotors},
 	{"MOT_PIN_RR", &motorPins[MOTOR_REAR_RIGHT], setupMotors},
 	{"MOT_PWM_FREQ", &pwmFrequency, setupMotors},
 	{"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]},
@@ -108,36 +77,17 @@ Parameter parameters[] = {
 	{"RC_THROTTLE", &throttleChannel},
 	{"RC_YAW", &yawChannel},
 	{"RC_MODE", &modeChannel},
 	// wifi
 	{"WIFI_MODE", &wifiMode},
 	{"WIFI_PORT_LOC", &udpLocalPort},
 	{"WIFI_PORT_REM", &udpRemotePort},
 	{"WIFI_LONG_RANGE", &wifiLongRange},
 	// espnow
 	{"ESPNOW_CHANNEL", &espnowChannel},
 	// mavlink
 	{"MAV_SYS_ID", &mavlinkSysId},
 	{"MAV_RATE_SLOW", &telemetrySlow.rate},
 	{"MAV_RATE_FAST", &telemetryFast.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},
 };
 void setupParameters() {
-	print("Setup parameters\n");
+	storage.begin("flix", false);
 	storage.begin("flix");
 	// Read parameters from storage
 	for (auto &parameter : parameters) {
 		if (!storage.isKey(parameter.name)) {
-			storage.putFloat(parameter.name, parameter.getValue()); // store default value
+			storage.putFloat(parameter.name, *parameter.variable);
 		}
-		parameter.setValue(storage.getFloat(parameter.name, 0));
+		*parameter.variable = storage.getFloat(parameter.name, *parameter.variable);
-		parameter.cache = parameter.getValue();
+		parameter.value = *parameter.variable;
 	}
 }
@@ -152,13 +102,13 @@ const char *getParameterName(int index) {
 float getParameter(int index) {
 	if (index < 0 || index >= parametersCount()) return NAN;
-	return parameters[index].getValue();
+	return *parameters[index].variable;
 }
 float getParameter(const char *name) {
 	for (auto &parameter : parameters) {
-		if (strcasecmp(parameter.name, name) == 0) {
+		if (strcmp(parameter.name, name) == 0) {
-			return parameter.getValue();
+			return *parameter.variable;
 		}
 	}
 	return NAN;
@@ -166,10 +116,8 @@ float getParameter(const char *name) {
 bool setParameter(const char *name, const float value) {
 	for (auto &parameter : parameters) {
-		if (strcasecmp(parameter.name, name) == 0) {
+		if (strcmp(parameter.name, name) == 0) {
-			if (parameter.integer && !isfinite(value)) return false; // can't set integer to NaN or Inf
+			*parameter.variable = value;
 			parameter.setValue(value);
 			if (parameter.callback) parameter.callback();
 			return true;
 		}
 	}
@@ -182,17 +130,16 @@ 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 (parameter.value == *parameter.variable) continue;
-		if (isnan(parameter.getValue()) && isnan(parameter.cache)) continue; // both are NAN
+		if (isnan(parameter.value) && isnan(*parameter.variable)) continue; // handle NAN != NAN
-
+		storage.putFloat(parameter.name, *parameter.variable);
-		storage.putFloat(parameter.name, parameter.getValue());
+		parameter.value = *parameter.variable;
 		parameter.cache = parameter.getValue(); // update cache
 	}
 }
 void printParameters() {
 	for (auto &parameter : parameters) {
-		print("%s = %g\n", parameter.name, parameter.getValue());
+		print("%s = %g\n", parameter.name, *parameter.variable);
 	}
 }
@@ -1,28 +0,0 @@
 // 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 "lpf.h"
 #include "util.h"
 float voltage = NAN;
 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;
 	float v = analogReadMilliVolts(voltagePin) * voltageScale / 1000.0f;
 	voltage = voltageFilter.update(v);
 }
@@ -6,27 +6,22 @@
 #include <SBUS.h>
 #include "util.h"
-SBUS rc(Serial1);
+SBUS rc(Serial2); // NOTE: Use RC(Serial2, 16, 17) if you use the old UART2 pins
 int rcRxPin = -1; // -1 means disabled
 uint16_t channels[16]; // raw rc channels
-int channelZero[16]; // calibration zero values
+float controlTime; // time of the last controls update
-int channelMax[16]; // calibration max values
+float channelZero[16]; // calibration zero values
 float channelMax[16]; // calibration max values
-float controlRoll, controlPitch, controlYaw, controlThrottle; // pilot's inputs, range [-1, 1]
+// Channels mapping (using float to store in parameters):
-float controlMode = NAN;
+float rollChannel = NAN, pitchChannel = NAN, throttleChannel = NAN, yawChannel = NAN, modeChannel = NAN;
 float controlTime = NAN; // time of the last controls update
 int rollChannel = -1, pitchChannel = -1, throttleChannel = -1, yawChannel = -1, modeChannel = -1; // channel mapping
 void setupRC() {
 	if (rcRxPin < 0) return;
 	print("Setup RC\n");
-	rc.begin(rcRxPin);
+	rc.begin();
 }
 bool readRC() {
 	if (rcRxPin < 0) return false;
 	if (rc.read()) {
 		SBUSData data = rc.data();
 		for (int i = 0; i < 16; i++) channels[i] = data.ch[i]; // copy channels data
@@ -43,34 +38,30 @@ void normalizeRC() {
 		controls[i] = mapf(channels[i], channelZero[i], channelMax[i], 0, 1);
 	}
 	// Update control values
-	controlRoll = rollChannel < 0 ? 0 : controls[rollChannel];
+	controlRoll = rollChannel >= 0 ? controls[(int)rollChannel] : NAN;
-	controlPitch = pitchChannel < 0 ? 0 : controls[pitchChannel];
+	controlPitch = pitchChannel >= 0 ? controls[(int)pitchChannel] : NAN;
-	controlYaw = yawChannel < 0 ? 0 : controls[yawChannel];
+	controlYaw = yawChannel >= 0 ? controls[(int)yawChannel] : NAN;
-	controlThrottle = throttleChannel < 0 ? 0 : controls[throttleChannel];
+	controlThrottle = throttleChannel >= 0 ? controls[(int)throttleChannel] : NAN;
-	controlMode = modeChannel < 0 ? NAN : controls[modeChannel]; // mode control is ineffective if not mapped
+	controlMode = modeChannel >= 0 ? controls[(int)modeChannel] : NAN;
 }
 void calibrateRC() {
-	if (rcRxPin < 0) {
+	uint16_t zero[16];
-		print("RC_RX_PIN = %d, set the RC pin!\n", rcRxPin);
+	uint16_t center[16];
-		return;
+	uint16_t max[16];
 	}
 	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, "2/8 Move sticks [3 sec]\n...     ...\n...     .o.\n.o.     ...\n");
+	calibrateRCChannel(NULL, zero, 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, center, "3/8 Move sticks [3 sec]\n...     ...\n.o.     .o.\n...     ...\n");
-	calibrateRCChannel(NULL, _, center, "4/8 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, _, "5/8 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(&pitchChannel, zero, _, "6/8 Move sticks [3 sec]\n...     .o.\n...     ...\n.o.     ...\n");
+	calibrateRCChannel(&pitchChannel, zero, max, "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(&rollChannel, zero, max, "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(&modeChannel, zero, max, "8/8 Put mode switch to max [3 sec]\n");
 	printRCCalibration();
 }
-void calibrateRCChannel(int *channel, uint16_t in[16], uint16_t out[16], const char *str) {
+void calibrateRCChannel(float *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
@@ -91,15 +82,15 @@ void calibrateRCChannel(int *channel, uint16_t in[16], uint16_t out[16], const c
 		channelZero[ch] = in[ch];
 		channelMax[ch] = out[ch];
 	} else {
-		*channel = -1;
+		*channel = NAN;
 	}
 }
 void printRCCalibration() {
 	print("Control   Ch     Zero   Max\n");
-	print("Roll      %-7d%-7d%-7d\n", rollChannel, rollChannel < 0 ? 0 : channelZero[rollChannel], rollChannel < 0 ? 0 : channelMax[rollChannel]);
+	print("Roll      %-7g%-7g%-7g\n", rollChannel, rollChannel >= 0 ? channelZero[(int)rollChannel] : NAN, rollChannel >= 0 ? channelMax[(int)rollChannel] : NAN);
-	print("Pitch     %-7d%-7d%-7d\n", pitchChannel, pitchChannel < 0 ? 0 : channelZero[pitchChannel], pitchChannel < 0 ? 0 : channelMax[pitchChannel]);
+	print("Pitch     %-7g%-7g%-7g\n", pitchChannel, pitchChannel >= 0 ? channelZero[(int)pitchChannel] : NAN, pitchChannel >= 0 ? channelMax[(int)pitchChannel] : NAN);
-	print("Yaw       %-7d%-7d%-7d\n", yawChannel, yawChannel < 0 ? 0 : channelZero[yawChannel], yawChannel < 0 ? 0 : channelMax[yawChannel]);
+	print("Yaw       %-7g%-7g%-7g\n", yawChannel, yawChannel >= 0 ? channelZero[(int)yawChannel] : NAN, yawChannel >= 0 ? channelMax[(int)yawChannel] : NAN);
-	print("Throttle  %-7d%-7d%-7d\n", throttleChannel, throttleChannel < 0 ? 0 : channelZero[throttleChannel], throttleChannel < 0 ? 0 : channelMax[throttleChannel]);
+	print("Throttle  %-7g%-7g%-7g\n", throttleChannel, throttleChannel >= 0 ? channelZero[(int)throttleChannel] : NAN, throttleChannel >= 0 ? channelMax[(int)throttleChannel] : NAN);
-	print("Mode      %-7d%-7d%-7d\n", modeChannel, modeChannel < 0 ? 0 : channelZero[modeChannel], modeChannel < 0 ? 0 : channelMax[modeChannel]);
+	print("Mode      %-7g%-7g%-7g\n", modeChannel, modeChannel >= 0 ? channelZero[(int)modeChannel] : NAN, modeChannel >= 0 ? channelMax[(int)modeChannel] : NAN);
 }
@@ -3,12 +3,12 @@
 // Fail-safe functions
 #define RC_LOSS_TIMEOUT 1
 #define DESCEND_TIME 10
 extern float controlTime;
 extern float controlRoll, controlPitch, controlThrottle, controlYaw;
 float rcLossTimeout = 1;
 float descendTime = 10;
 void failsafe() {
 	rcLossFailsafe();
 	autoFailsafe();
@@ -16,8 +16,9 @@ void failsafe() {
 // RC loss failsafe
 void rcLossFailsafe() {
 	if (controlTime == 0) return; // no RC at all
 	if (!armed) return;
-	if (t - controlTime > rcLossTimeout) {
+	if (t - controlTime > RC_LOSS_TIMEOUT) {
 		descend();
 	}
 }
@@ -26,7 +27,7 @@ void rcLossFailsafe() {
 void descend() {
 	mode = AUTO;
 	attitudeTarget = Quaternion();
-	thrustTarget -= dt / descendTime;
+	thrustTarget -= dt / DESCEND_TIME;
 	if (thrustTarget < 0) {
 		thrustTarget = 0;
 		armed = false;
@@ -37,8 +38,8 @@ 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
+		// controls changed
-		if (mode == AUTO && invalid(controlMode)) mode = STAB; // regain control by the pilot
+		if (mode == AUTO) mode = STAB; // regain control by the pilot
 	}
 	roll = controlRoll;
 	pitch = controlPitch;
@@ -3,8 +3,6 @@
 // Time related functions
 float t = NAN; // current time, s
 float dt; // time delta with the previous step, s
 float loopRate; // Hz
 void step() {
@@ -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;
@@ -34,29 +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 tx buffering and resends
 class ESPNOWSerial : public ESP_NOW_Serial_Class {
 public:
 	using ESP_NOW_Serial_Class::ESP_NOW_Serial_Class;
 	void onSent(bool success) override {} // disable resends
 	size_t write(const uint8_t *data, size_t len) override {
 		return ESP_NOW_Peer::send(data, len); // pure send without buffering
 	}
 };
 // Rate limiter
 class Rate {
 public:
@@ -35,6 +35,7 @@ public:
 		z = NAN;
 	}
 	float norm() const {
 		return sqrt(x * x + y * y + z * z);
 	}
@@ -105,23 +106,10 @@ 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 (direction.zero()) {
-			if (dot(a, b) > 0) { // same direction
+			// vectors are opposite, return any perpendicular vector
-				return Vector(0, 0, 0);
+			return cross(a, Vector(1, 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);
@@ -1,129 +1,49 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
-// Wi-Fi and ESP-NOW communication
+// Wi-Fi support
 #if WIFI_ENABLED
 #include <WiFi.h>
 #include <WiFiAP.h>
 #include <WiFiUdp.h>
 #include <MacAddress.h>
 #include <ESP32_NOW_Serial.h>
 #include "Preferences.h"
 #include "util.h"
-extern Preferences storage; // use the main preferences storage
+#define WIFI_SSID "flix"
 #define WIFI_PASSWORD "flixwifi"
 #define WIFI_UDP_PORT 14550
 #define WIFI_UDP_REMOTE_PORT 14550
 #define WIFI_UDP_REMOTE_ADDR "255.255.255.255"
 const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
 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;
 void setupWiFi() {
 	print("Setup Wi-Fi\n");
-	WiFi.enableLongRange(wifiLongRange);
+	WiFi.softAP(WIFI_SSID, WIFI_PASSWORD);
-
+	udp.begin(WIFI_UDP_PORT);
 	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);
 	} else if (wifiMode == W_STA) {
 		WiFi.begin(storage.getString("WIFI_STA_SSID", "").c_str(), storage.getString("WIFI_STA_PASS", "").c_str());
 		udp.begin(udpLocalPort);
 	} else 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) {
+	if (WiFi.softAPIP() == IPAddress(0, 0, 0, 0) && WiFi.status() != WL_CONNECTED) return;
-		espnow.write(buf, len);
+	udp.beginPacket(udp.remoteIP() ? udp.remoteIP() : WIFI_UDP_REMOTE_ADDR, WIFI_UDP_REMOTE_PORT);
 		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("MAC: %s\n", WiFi.softAPmacAddress().c_str());
-		print("Mode: ESP-NOW\n");
+	print("SSID: %s\n", WiFi.softAPSSID().c_str());
-		print("ESP-NOW version: %d\n", ESP_NOW.getVersion());
+	print("Password: %s\n", WIFI_PASSWORD);
-		print("Max packet size: %d\n", ESP_NOW.getMaxDataLen());
+	print("Clients: %d\n", WiFi.softAPgetStationNum());
-		print("MAC: %s\n", WiFi.softAPmacAddress().c_str());
+	print("Status: %d\n", WiFi.status());
-		print("Peer MAC: %s\n", MacAddress(espnow.addr()).toString().c_str());
+	print("IP: %s\n", WiFi.softAPIP().toString().c_str());
-		print("Encrypted: %d\n", espnow.isEncrypted());
+	print("Remote IP: %s\n", udp.remoteIP().toString().c_str());
 		print("Channel: %d\n", espnow.getChannel());
 	} 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");
 	}
 	print("MAVLink connected: %d\n", mavlinkConnected);
 }
-void configWiFi(int mode, const char *first, const char *second) {
+#endif
 	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 : "");
 	} else {
 		print("Invalid configuration\n");
 		return;
 	}
 	print("✓ Reboot to apply new settings\n");
 }
@@ -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:
@@ -167,9 +165,6 @@ 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;
 unsigned long __resetTime = 0;
@@ -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; };
 };
@@ -13,7 +13,7 @@ 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(int rxpin = -1, int txpin = -1, bool inv = true, bool fast = false) {};
+	void begin() {};
 	bool read() { return joystickInit(); };
 	SBUSData data() {
 		SBUSData data;
@@ -9,44 +9,42 @@
 #include "quaternion.h"
 #include "Arduino.h"
 #include "wifi.h"
 #include "lpf.h"
-extern float t, dt;
+#define WIFI_ENABLED 1
 extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
 extern Vector rates;
 extern Quaternion attitude;
 extern bool landed;
 extern float motors[4];
-Vector gyro, acc, imuRotation;
+float t = NAN;
-Vector accBias, gyroBias, accScale(1, 1, 1);
+float dt;
-LowPassFilter<Vector> gyroBiasFilter(0);
+float motors[4];
 float controlRoll, controlPitch, controlYaw, controlThrottle = NAN;
 float controlMode = NAN;
 Vector acc;
 Vector gyro;
 Vector rates;
 Quaternion attitude;
 bool landed;
 Vector imuRotation;
 // 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 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(float *channel, uint16_t zero[16], uint16_t max[16], const char *str);
 void printRCCalibration();
 void printLogHeader();
 void printLogData();
@@ -58,7 +56,6 @@ 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();
@@ -75,7 +72,8 @@ void resetParameters();
 void setLED(bool on) {};
 void calibrateGyro() { print("Skip gyro calibrating\n"); };
 void calibrateAccel() { print("Skip accel calibrating\n"); };
 void calibrateLevel() { print("Skip level 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"); };
+Vector accBias, gyroBias, accScale(1, 1, 1);
@@ -27,7 +27,6 @@
 #include "mavlink.ino"
 #include "motors.ino"
 #include "parameters.ino"
 #include "power.ino"
 #include "rc.ino"
 #include "time.ino"
@@ -73,8 +72,6 @@ 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) {}
@@ -11,10 +11,9 @@
 #include <sys/poll.h>
 #include <gazebo/gazebo.hh>
-int wifiMode = 1; // mock
+#define WIFI_UDP_PORT 14580
-int udpLocalPort = 14580;
+#define WIFI_UDP_REMOTE_PORT 14550
-int udpRemotePort = 14550;
+#define WIFI_UDP_REMOTE_ADDR "255.255.255.255"
 const char *udpRemoteIP = "255.255.255.255";
 int wifiSocket;
@@ -23,22 +22,22 @@ void setupWiFi() {
 	sockaddr_in addr; // local address
 	addr.sin_family = AF_INET;
 	addr.sin_addr.s_addr = INADDR_ANY;
-	addr.sin_port = htons(udpLocalPort);
+	addr.sin_port = htons(WIFI_UDP_PORT);
 	if (bind(wifiSocket, (sockaddr *)&addr, sizeof(addr))) {
-		gzerr << "Failed to bind WiFi UDP socket on port " << udpLocalPort << std::endl;
+		gzerr << "Failed to bind WiFi UDP socket on port " << WIFI_UDP_PORT << std::endl;
 		return;
 	}
 	int broadcast = 1;
 	setsockopt(wifiSocket, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof(broadcast)); // enable broadcast
-	gzmsg << "WiFi UDP socket initialized on port " << udpLocalPort << " (remote port " << udpRemotePort << ")" << std::endl;
+	gzmsg << "WiFi UDP socket initialized on port " << WIFI_UDP_PORT << " (remote port " << WIFI_UDP_REMOTE_PORT << ")" << 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(udpRemoteIP);
+	addr.sin_addr.s_addr = inet_addr(WIFI_UDP_REMOTE_ADDR);
-	addr.sin_port = htons(udpRemotePort);
+	addr.sin_port = htons(WIFI_UDP_REMOTE_PORT);
 	sendto(wifiSocket, buf, len, 0, (sockaddr *)&addr, sizeof(addr));
 }
@@ -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);
 		}
 	}
 }
@@ -10,7 +10,6 @@ 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)
@@ -24,11 +23,11 @@ print('> imu')
 print(flix.cli('imu'))
 print('=== Get parameter...')
-pitch_p = flix.get_param('CTL_P_P')
+pitch_p = flix.get_param('PITCH_P')
-print('CTL_P_P = ', pitch_p)
+print('PITCH_P = ', pitch_p)
 print('=== Set parameter...')
-flix.set_param('CTL_P_P', pitch_p)
+flix.set_param('PITCH_P', pitch_p)
 print('=== Wait for gyro update...')
 print('Gyro: ', flix.wait('gyro'))
@@ -13,7 +13,7 @@ lines = []
 print('Downloading log...')
 count = 0
-dev.write('log dump\n'.encode())
+dev.write('log\n'.encode())
 while True:
    line = dev.readline()
    if not line:
@@ -43,7 +43,6 @@ records = [record for record in records if record[0] != 0]
 print(f'Received records: {len(records)}')
 os.makedirs(f'{DIR}/log', exist_ok=True)
 log = open(f'{DIR}/log/{datetime.datetime.now().isoformat()}.csv', 'wb')
 log.write(header.encode() + b'\n')
 for record in records:
@@ -24,20 +24,19 @@ 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
 ```
 ### 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.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]
@@ -93,18 +92,17 @@ Full list of events:
 |-----|-----------|----------------|
 |`connected`|Connected to the drone||
 |`disconnected`|Connection is lost||
-|`armed`|Armed state update|Armed state *(bool)*|
+|`armed`|Armed state update|Armed state (*bool*)|
-|`mode`|Flight mode update|Flight mode *(str)*|
+|`mode`|Flight mode update|Flight mode (*str*)|
-|`landed`|Landed state update|Landed state *(bool)*|
+|`landed`|Landed state update|Landed state (*bool*)|
-|`voltage`|Battery voltage update|Voltage *(float)*|
+|`print`|The drone sends text to the console|Text|
-|`print`|The drone prints text to the console|Text|
+|`attitude`|Attitude update|Attitude quaternion (*list*)|
-|`attitude`|Attitude update|Attitude quaternion *(list)*|
+|`attitude_euler`|Attitude update|Euler angles (*list*)|
-|`attitude_euler`|Attitude update|Euler angles *(list)*|
+|`rates`|Angular rates update|Angular rates (*list*)|
-|`rates`|Angular rates update|Angular rates *(list)*|
+|`channels`|Raw RC channels update|Raw RC channels (*list*)|
-|`channels`|Raw RC channels update|Raw RC channels *(list)*|
+|`motors`|Motor outputs update|Motor outputs (*list*)|
-|`motors`|Motor outputs update|Motor outputs *(list)*|
+|`acc`|Accelerometer update|Accelerometer output (*list*)|
-|`acc`|Accelerometer update|Accelerometer output *(list)*|
+|`gyro`|Gyroscope update|Gyroscope output (*list*)|
 |`gyro`|Gyroscope update|Gyroscope output *(list)*|
 |`mavlink`|Received MAVLink message|Message object|
 |`mavlink.<message_name>`|Received specific MAVLink message|Message object|
 |`mavlink.<message_id>`|Received specific MAVLink message|Message object|
@@ -114,13 +112,13 @@ Full list of events:
 > [!NOTE]
 > Update events trigger on every new piece of data from the drone, and do not mean the value has changed.
-### Basic methods
+### Common methods
 Get and set firmware parameters using `get_param` and `set_param` methods:
 ```python
-pitch_p = flix.get_param('CTL_P_P')  # get parameter value
+pitch_p = flix.get_param('PITCH_P')  # get parameter value
-flix.set_param('CTL_P_P', 5)         # set parameter value
+flix.set_param('PITCH_P', 5)         # set parameter value
 ```
 Execute console commands using `cli` method. This method returns the command response:
@@ -279,3 +277,7 @@ logger = logging.getLogger('flix')
 logger.setLevel(logging.DEBUG)  # be more verbose
 logger.setLevel(logging.WARNING)  # be less verbose
 ```
 ## Stability
 The library is in development stage. The API is not stable.
@@ -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 +26,6 @@ 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]
@@ -70,7 +68,7 @@ class Flix:
        self._heartbeat_thread.start()
        if wait_connection:
            self.wait('mavlink.HEARTBEAT')
-            time.sleep(0.6) # give some time to receive initial state
+            time.sleep(0.2) # give some time to receive initial state
    def _init_state(self):
        self.attitude = [1, 0, 0, 0]
@@ -140,7 +138,7 @@ class Flix:
        while True:
            try:
                msg: Optional[mavlink.MAVLink_message] = self.connection.recv_match(blocking=True)
-                if msg is None or msg.get_srcSystem() != self.system_id:
+                if msg is None:
                    continue
                self._connected()
                msg_dict = msg.to_dict()
@@ -187,16 +185,11 @@ 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 / 1000, msg.yacc / 1000, msg.zacc / 1000])
            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')
@@ -1,6 +1,6 @@
 [project]
 name = "pyflix"
-version = "0.15"
+version = "0.11"
 description = "Python API for Flix drone"
 authors = [{ name="Oleg Kalachev", email="okalachev@gmail.com" }]
 license = "MIT"
Author	SHA1	Message	Date
Oleg Kalachev	0908674a60	Add level calibration	2025-12-26 11:29:12 +03:00
Oleg Kalachev	13a7e67b92	Add parameters for IMU orientation definition	2025-12-26 06:29:19 +03:00
		`@@ -1,3 +0,0 @@`
			`# ESPNOW-proxy`

			`Proxy sketch for using ESP-NOW connection with Flix drone.`