Rename lpf.h to filter.h

To implement more filters (like notch) potentially.

.github/workflows/build.yml

@@ -10,23 +10,31 @@ on:
 jobs:
   build_linux:
     runs-on: ubuntu-latest
+    env:
+        ARDUINO_SKETCH_ALWAYS_EXPORT_BINARIES: 1
     steps:
     - uses: actions/checkout@v4
     - name: Install Arduino CLI
       run: curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=/usr/local/bin sh
-    - name: Build firmware
-      env:
-        ARDUINO_SKETCH_ALWAYS_EXPORT_BINARIES: 1
+    - name: Build firmware for ESP32
       run: make
+    - name: Build firmware for ESP32-C3
+      run: make BOARD=esp32:esp32:esp32c3
+    - name: Build firmware for ESP32-S3
+      run: make BOARD=esp32:esp32:esp32s3:CDCOnBoot=cdc
+    - name: Build firmware for ESP32-S3 with QSPI PSRAM
+      run: make BOARD=esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=enabled EXTRA=--output-dir=flix/build/esp32.esp32.esp32s3.qspi
+    - name: Build firmware for ESP32-S3 with OPI PSRAM
+      run: make BOARD=esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=opi EXTRA=--output-dir=flix/build/esp32.esp32.esp32s3.opi
+    - name: Build firmware for Flix2
+      run: make BOARD=esp32:esp32:esp32s3:FlashSize=4M,CDCOnBoot=cdc,PSRAM=opi EXTRA='--build-property "compiler.cpp.extra_flags=-DFLIX2" --output-dir=flix/build/esp32.esp32.flix2'
     - name: Upload binaries
       uses: actions/upload-artifact@v4
       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 espnow-proxy
+      run: arduino-cli compile --fqbn esp32:esp32:esp32 tools/espnow-proxy
     - name: Check c_cpp_properties.json
       run: tools/check_c_cpp_properties.py
 
@@ -64,7 +72,7 @@ jobs:
         apt-get update
         DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget build-essential cmake g++ pkg-config gnupg2 lsb-release sudo
     - name: Install Arduino CLI
-      uses: arduino/setup-arduino-cli@v1.1.1
+      run: curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=/usr/local/bin sh
     - uses: actions/checkout@v4
     - name: Install Gazebo
       run: |

.github/workflows/docs.yml

@@ -8,6 +8,7 @@ on:
 
 permissions:
   contents: read
+  actions: read
   pages: write
   id-token: write
 
@@ -30,6 +31,38 @@ jobs:
       run: cargo install mdbook --vers 0.4.43 --locked
     - name: Build book
       run: cd docs && mdbook build
+    - name: Wait for Build to complete
+      uses: lewagon/wait-on-check-action@v1.9.1
+      with:
+        ref: ${{ github.sha }}
+        check-name: build_linux
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        wait-interval: 30
+    - name: Find firmware binaries
+      id: build_run
+      run: |
+        RUN_ID=$(gh api "repos/${{ github.repository }}/actions/workflows/build.yml/runs?head_sha=${{ github.sha }}&per_page=1" --jq '.workflow_runs[0].id')
+        echo "id=$RUN_ID" >> $GITHUB_OUTPUT
+      env:
+        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    - name: Download firmware binaries
+      uses: actions/download-artifact@v4
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        repository: ${{ github.repository }}
+        run-id: ${{ steps.build_run.outputs.id }}
+        name: firmware-binary
+        path: docs/build
+    - name: Create shortcuts for firmware binaries
+      working-directory: docs/build
+      run: |
+        for FQBN in esp32.esp32.*; do
+          zip -r $FQBN.zip $FQBN
+          BOARD="${FQBN#esp32.esp32.}"
+          ln -s "$FQBN/flix.ino.merged.bin" "flix.$BOARD.merged.bin"
+          ln -s "$FQBN/flix.ino.bin" "flix.$BOARD.bin"
+          ln -s "$FQBN/flix.ino.bootloader.bin" "flix.$BOARD.bootloader.bin"
+        done
     - name: Upload artifact
       uses: actions/upload-pages-artifact@v3
       with:

Makefile

@@ -1,10 +1,10 @@
-BOARD = esp32:esp32:d1_mini32:DebugLevel=error
+BOARD = esp32:esp32:esp32
 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*))
 
 export ARDUINO_NETWORK_CONNECTION_TIMEOUT := 1h
 
 build: .core .libs
-	arduino-cli compile --fqbn $(BOARD) flix
+	arduino-cli compile --fqbn $(BOARD) --build-property "build.core_debug_level=1" flix $(EXTRA)
 
 upload: build
 	arduino-cli upload --fqbn $(BOARD) -p "$(PORT)" flix

README.md

@@ -55,6 +55,12 @@ Outdoor flights demo video of the current prototype:
 
 <a href="https://youtu.be/KXlNmvUTi4g"><img width=300 src="https://i3.ytimg.com/vi/KXlNmvUTi4g/maxresdefault.jpg"></a>
 
+### Position control
+
+The position control feature is in development. RoboCamp 2026 demo (using an overhead camera, [sources](https://github.com/xTimop/flix-poscontrol/compare/robolager2026...xTimop:flix-poscontrol:poscontrol)):
+
+<a href="https://youtu.be/369Xowm4HcU"><img width=300 src="https://i3.ytimg.com/vi/369Xowm4HcU/maxresdefault.jpg"></a>
+
 ## Simulation
 
 The simulator is implemented using Gazebo and runs the original Arduino code:

docs/usage.md

@@ -1,20 +1,48 @@
 # Usage: build, setup and flight
 
-To fly Flix quadcopter, you need to build the firmware, upload it to the ESP32 board, and set up the drone for flight.
+To fly Flix quadcopter, you need to upload the firmware to the ESP32 board, and set up the drone for flight.
 
-To get the firmware sources, clone the repository using git:
+## Uploading the firmware
+
+You can either use the **prebuilt binaries** or **build the firmware** from sources — this will let you modify the firmware and add new features.
+
+### Prebuilt binaries (the easiest way)
+
+1. Download the latest firmware file using the following links:
+
+   <!-- markdownlint-disable MD044 -->
+   |Type|Boards|Link|
+   |-|-|-|
+   |ESP32|DevKit, D1 Mini|[`quadcopter.dev/flix.esp32.merged.bin`](https://quadcopter.dev/flix.esp32.merged.bin)|
+   |ESP32-S3|Most S3 based|[`quadcopter.dev/flix.esp32s3.merged.bin`](https://quadcopter.dev/flix.esp32s3.merged.bin)|
+   |ESP32-S3 (2MB PSRAM)|S3 Super Mini, S3 Zero (2MB PSRAM)|[`quadcopter.dev/flix.esp32s3.qspi.merged.bin`](https://quadcopter.dev/flix.esp32s3.qspi.merged.bin)|
+   |ESP32-S3 (8/16MB PSRAM)|S3 Zero (8MB PSRAM)|[`quadcopter.dev/flix.esp32s3.opi.merged.bin`](https://quadcopter.dev/flix.esp32s3.opi.merged.bin)|
+   |ESP32-C3|C3 Super Mini|[`quadcopter.dev/flix.esp32c3.merged.bin`](https://quadcopter.dev/flix.esp32c3.merged.bin)|
+   |Flix2|Flix2 board|[`quadcopter.dev/flix.flix2.merged.bin`](https://quadcopter.dev/flix.flix2.merged.bin)|
+   <!-- markdownlint-enable MD044 -->
+
+2. Flash your ESP32 board using [ESP32 Web Flasher](https://www.espboards.dev/tools/program/):
+
+   <img src="img/web-flasher.png" width="400">
+
+   * Connect the board to your computer, press *Connect to ESP*, choose the serial port.
+   * Go to the *Flash* tab.
+   * Choose the downloaded firmware file, set *Flash address* to *0* (important).
+   * Click *Program* button and wait until the process is finished.
+
+### Building from sources (flexible)
+
+You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
+
+Get the sources using git:
 
 ```bash
 git clone https://github.com/okalachev/flix.git && cd flix
 ```
 
-Beginners can [download the source code as a ZIP archive](https://github.com/okalachev/flix/archive/refs/heads/master.zip).
+Beginners can [download the sources as a ZIP archive](https://github.com/okalachev/flix/archive/refs/heads/master.zip).
 
-## Building the firmware
-
-You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
-
-### Arduino IDE (Windows, Linux, macOS)
+#### Arduino IDE (Windows, Linux, macOS)
 
 <img src="img/arduino-ide.png" width="400" alt="Flix firmware open in Arduino IDE">
 
@@ -25,11 +53,11 @@ You can build and upload the firmware using either **Arduino IDE** (easier for b
    * `FlixPeriph`, the latest version.
    * `MAVLink`, version 2.0.25.
 5. Open the `flix/flix.ino` sketch from downloaded firmware sources in Arduino IDE.
-6. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini) and the port.
+6. Connect your ESP32 board to the computer and choose correct board type in Arduino IDE (*WEMOS D1 MINI ESP32* for ESP32 Mini, *ESP32S3 Dev Module* for ESP32-S3 Super Mini) and the port.
 7. Set *Tools* ⇒ *Core Debug Level* to *Error* to see the errors in the serial console. Set *Tools* ⇒ *USB CDC on Boot* to *Enabled* for ESP32-S3/ESP32-C3 boards.
 8. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
 
-### Command line (Windows, Linux, macOS)
+#### Command line (Windows, Linux, macOS)
 
 1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
 
@@ -61,7 +89,7 @@ You can build and upload the firmware using either **Arduino IDE** (easier for b
    For ESP32-S3/ESP32-C3 boards, set the appropriate [FQBN](https://docs.arduino.cc/arduino-cli/FAQ/#whats-the-fqbn-string) using `BOARD` parameter:
 
    ```bash
-   make BOARD=esp32:esp32:esp32s3:DebugLevel=error,FlashSize=4M,CDCOnBoot=cdc upload
+   make BOARD=esp32:esp32:esp32s3:FlashSize=4M,CDCOnBoot=cdc upload
    ```
 
 See other available Make commands in [Makefile](../Makefile).
@@ -71,15 +99,6 @@ See other available Make commands in [Makefile](../Makefile).
 
 ## Before first flight
 
-### Choose the IMU model
-
-In case if using different IMU model than MPU9250, change `imu` variable declaration in the `imu.ino`:
-
-```cpp
-ICM20948 imu(SPI);  // For ICM-20948
-MPU6050 imu(Wire);  // For MPU-6050
-```
-
 ### Connect using QGroundControl
 
 QGroundControl is a ground control station software that can be used to monitor and control the drone.
@@ -105,7 +124,7 @@ To access the console using serial port:
 To access the console using QGroundControl:
 
 1. Connect to the drone using QGroundControl app.
-2. Go to the QGroundControl menu ⇒ *Vehicle Setup* ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
+2. Go to the QGroundControl menu ⇒ *Analyze Tools* ⇒ *MAVLink Console*.
 
 <img src="img/cli.png" width="400">
 
@@ -120,6 +139,17 @@ The drone is configured using parameters. To access and modify them, go to the Q
 
 You can also work with parameters using `p` command in the console. Parameter names are case-insensitive.
 
+### Configure the IMU
+
+1. Configure the following parameters for the IMU:
+   * `IMU_MODEL` — IMU model (1 for MPU-9250/MPU-6500, 2 for ICM-20948, 3 for MPU-6050, 4 for ICM-40609-D).
+   * `IMU_BUS` — communication bus (0 for SPI, 1 for I²C).
+   * `IMU_PIN_SCK`, `IMU_PIN_MISO`, `IMU_PIN_MOSI`, `IMU_PIN_CS` — SPI pin numbers.
+   * `IMU_PIN_SCL`, `IMU_PIN_SDA` — I²C pin numbers.
+   * `IMU_PIN_INT` — IMU data ready pin number (-1 if not used).
+2. Reboot the drone.
+3. Check the IMU is working using `imu` command in the console (should print `status: OK`).
+
 ### Define IMU orientation
 
 The IMU orientation (relative to the drone's axes) is defined using the parameters: `IMU_ROT_ROLL`, `IMU_ROT_PITCH`, and `IMU_ROT_YAW`.
@@ -148,9 +178,9 @@ Before flight you need to calibrate the accelerometer:
 
 If using non-default motor pins, set the pin numbers using the parameters: `MOTOR_PIN_FL`, `MOTOR_PIN_FR`, `MOTOR_PIN_RL`, `MOTOR_PIN_RR` (front-left, front-right, rear-left, rear-right respectively).
 
-Certain ESP32 models (such as ESP32-S3 and ESP32-C3) support a lower maximum PWM frequency; on these boards the parameter `MOT_PWM_FREQ` should be set to 38000 Hz.
+#### Brushless motors
 
-If using brushless motors and ESCs:
+If using brushless motors with ESCs:
 
 1. Set the appropriate PWM using the parameters: `MOT_PWM_STOP`, `MOT_PWM_MIN`, and `MOT_PWM_MAX` (1000, 1000, and 2000 is typical).
 2. Decrease the PWM frequency using the `MOT_PWM_FREQ` parameter (400 is typical).
@@ -158,7 +188,7 @@ If using brushless motors and ESCs:
 > [!CAUTION]
 > **Remove the props when configuring the motors!** If improperly configured, you may not be able to stop them.
 
-### Battery voltage monitoring
+### Battery voltage monitoring (optional)
 
 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:
 
@@ -333,7 +363,7 @@ 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:
+2. Open Serial Monitor in Arduino IDE or use `make monitor` command. The ESP32 will print its MAC address and generated encryption key, for example:
 
    ```
    espnow 7a:c8:e3:eb:bf:e9 &PiuSysxP9+$L&5E
@@ -352,7 +382,10 @@ To setup ESP-NOW communication:
    * 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.
+5. Click *Save*, click *Connect*. QGroundControl should connect to the drone using ESP-NOW and begin showing the telemetry.
+
+> [!TIP]
+> Make sure Arduino IDE is not running when using ESP-NOW proxy board, as it may block the serial port.
 
 ## Flight log
 

docs/user.md

@@ -4,6 +4,15 @@ This page contains user-built drones based on the Flix project. Publish your pro
 
 ---
 
+Author: [Oleg1405](https://t.me/Oleg1405).<br>
+Description: ESP32 Mini, MPU-6500 IMU, boost converter, BT2.0 power connector, 65 mm props, BetaFPV ELRS Lite Receiver, Radiomaster Pocket + Mavlink Joystick (Android) control.
+
+<img src="img/user/oleg1405/1.jpg" height=300>
+
+[Flight video](https://www.youtube.com/shorts/rbXV4sHbpso).
+
+---
+
 Author: Alican Erüst.<br>
 Description: QX95 mm frame, 55 mm propellers, 3.7 V 25C 1050 mAh LiPo battery, MPU6050 IMU, Logitech F310 gamepad controller, with a total quadcopter weight of 66 g.
 

flix/cli.ino

@@ -6,7 +6,7 @@
 #include "pid.h"
 #include "vector.h"
 #include "util.h"
-#include "lpf.h"
+#include "filter.h"
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
 extern const int RAW, ACRO, STAB, AUTO;

flix/config.h

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

flix/control.ino

@@ -6,34 +6,9 @@
 #include "vector.h"
 #include "quaternion.h"
 #include "pid.h"
-#include "lpf.h"
+#include "filter.h"
 #include "util.h"
 
-#define PITCHRATE_P 0.05
-#define PITCHRATE_I 0.2
-#define PITCHRATE_D 0.001
-#define PITCHRATE_I_LIM 0.3
-#define ROLLRATE_P PITCHRATE_P
-#define ROLLRATE_I PITCHRATE_I
-#define ROLLRATE_D PITCHRATE_D
-#define ROLLRATE_I_LIM PITCHRATE_I_LIM
-#define YAWRATE_P 0.3
-#define YAWRATE_I 0.0
-#define YAWRATE_D 0.0
-#define YAWRATE_I_LIM 0.3
-#define ROLL_P 6
-#define ROLL_I 0
-#define ROLL_D 0
-#define PITCH_P ROLL_P
-#define PITCH_I ROLL_I
-#define PITCH_D ROLL_D
-#define YAW_P 3
-#define PITCHRATE_MAX radians(360)
-#define ROLLRATE_MAX radians(360)
-#define YAWRATE_MAX radians(300)
-#define TILT_MAX radians(30)
-#define RATES_D_LPF_ALPHA 0.2 // cutoff frequency ~ 40 Hz
-
 const int RAW = 0, ACRO = 1, STAB = 2, AUTO = 3; // flight modes
 int mode = STAB;
 bool armed = false;
@@ -44,14 +19,14 @@ 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);
-PID rollPID(ROLL_P, ROLL_I, ROLL_D);
-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;
+PID rollRatePID(0.05, 0.2, 0.001, 0.3, 0.2);
+PID pitchRatePID(0.05, 0.2, 0.001, 0.3, 0.2);
+PID yawRatePID(0.3, 0, 0, 0.3);
+PID rollPID(6);
+PID pitchPID(6);
+PID yawPID(3);
+Vector maxRate(radians(360), radians(360), radians(360));
+float tiltMax = radians(30);
 int flightModes[] = {STAB, STAB, STAB}; // map for rc mode switch
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;

flix/estimate.ino

@@ -5,7 +5,7 @@
 
 #include "quaternion.h"
 #include "vector.h"
-#include "lpf.h"
+#include "filter.h"
 #include "util.h"
 
 Vector rates; // estimated angular rates, rad/s

flix/imu.ino

@@ -4,12 +4,17 @@
 // Work with the IMU sensor
 
 #include <SPI.h>
+#include <Wire.h>
 #include <FlixPeriph.h>
 #include "vector.h"
-#include "lpf.h"
+#include "filter.h"
 #include "util.h"
 
-MPU9250 imu(SPI);
+IMU *imu;
+int imuModel = -1; // 1 - MPU9250, 2 - ICM20948, 3 - MPU6050, 4 - ICM40609D
+int imuBus = 0; // 0 - SPI, 1 - I2C
+int imuSckPin = SCK, imuMisoPin = MISO, imuMosiPin = MOSI, imuCsPin = SS, imuIntPin = -1;
+int imuSdaPin = SDA, imuSclPin = SCL;
 Vector imuRotation(0, 0, PI / 2); // imu orientation as Euler angles
 
 Vector gyro; // gyroscope output, rad/s
@@ -23,22 +28,35 @@ LowPassFilter<Vector> gyroBiasFilter(0.001);
 
 void setupIMU() {
 	print("Setup IMU\n");
-	imu.begin();
+	free(imu);
+	if (imuModel == 3) imuBus = 1; // MPU6050 is I2C only
+
+	if (imuBus == 0) {
+		// SPI connection
+		SPI.begin(imuSckPin, imuMisoPin, imuMosiPin);
+		imu = IMU::create(imuModel, SPI, imuCsPin, imuIntPin);
+	} else {
+		// I2C connection
+		Wire.setPins(imuSdaPin, imuSclPin);
+		imu = IMU::create(imuModel, Wire, imuIntPin);
+	}
+
+	imu->begin();
 	configureIMU();
 }
 
 void configureIMU() {
-	imu.setAccelRange(imu.ACCEL_RANGE_4G);
-	imu.setGyroRange(imu.GYRO_RANGE_2000DPS);
-	imu.setDLPF(imu.DLPF_MAX);
-	imu.setRate(imu.RATE_1KHZ_APPROX);
-	imu.setupInterrupt();
+	imu->setAccelRange(IMU::ACCEL_RANGE_4G);
+	imu->setGyroRange(IMU::GYRO_RANGE_2000DPS);
+	imu->setDLPF(IMU::DLPF_MAX);
+	imu->setRate(IMU::RATE_1KHZ_APPROX);
+	imu->setupInterrupt();
 }
 
 void readIMU() {
-	imu.waitForData();
-	imu.getGyro(gyro.x, gyro.y, gyro.z);
-	imu.getAccel(acc.x, acc.y, acc.z);
+	imu->waitForData();
+	imu->getGyro(gyro.x, gyro.y, gyro.z);
+	imu->getAccel(acc.x, acc.y, acc.z);
 	calibrateGyroOnce();
 
 	// Apply scale and bias
@@ -60,7 +78,7 @@ void calibrateGyroOnce() {
 
 void calibrateAccel() {
 	print("Calibrating accelerometer\n");
-	imu.setAccelRange(imu.ACCEL_RANGE_2G); // the most sensitive mode
+	imu->setAccelRange(IMU::ACCEL_RANGE_2G); // the most sensitive mode
 
 	print("1/6 Place level [8 sec]\n");
 	pause(8);
@@ -94,9 +112,9 @@ void calibrateAccelOnce() {
 	// Compute the average of the accelerometer readings
 	acc = Vector(0, 0, 0);
 	for (int i = 0; i < samples; i++) {
-		imu.waitForData();
+		imu->waitForData();
 		Vector sample;
-		imu.getAccel(sample.x, sample.y, sample.z);
+		imu->getAccel(sample.x, sample.y, sample.z);
 		acc = acc + sample;
 	}
 	acc = acc / samples;
@@ -121,17 +139,18 @@ void printIMUCalibration() {
 }
 
 void printIMUInfo() {
-	imu.status() ? print("status: ERROR %d\n", imu.status()) : print("status: OK\n");
-	print("model: %s\n", imu.getModel());
-	print("who am I: 0x%02X\n", imu.whoAmI());
+	imu->status() ? print("status: ERROR %d\n", imu->status()) : print("status: OK\n");
+	print("model: %s\n", imu->getModel());
+	print("who am I: 0x%02X\n", imu->whoAmI());
 	print("rate: %.0f\n", loopRate);
-	print("temperature: %.1f °C\n", imu.getTemp());
+	print("interrupt mode: %s\n", imuIntPin != -1 ? "pin" : "timer");
+	print("temperature: %.1f °C\n", imu->getTemp());
 	print("gyro: %f %f %f\n", gyro.x, gyro.y, gyro.z);
 	print("acc: %f %f %f\n", acc.x, acc.y, acc.z);
-	imu.waitForData();
+	imu->waitForData();
 	Vector rawGyro, rawAcc;
-	imu.getGyro(rawGyro.x, rawGyro.y, rawGyro.z);
-	imu.getAccel(rawAcc.x, rawAcc.y, rawAcc.z);
+	imu->getGyro(rawGyro.x, rawGyro.y, rawGyro.z);
+	imu->getAccel(rawAcc.x, rawAcc.y, rawAcc.z);
 	print("raw gyro: %f %f %f\n", rawGyro.x, rawGyro.y, rawGyro.z);
 	print("raw acc: %f %f %f\n", rawAcc.x, rawAcc.y, rawAcc.z);
 }

flix/mavlink.ino

@@ -17,7 +17,7 @@ Rate telemetryRC(10);
 Rate telemetryMotors(10);
 Rate telemetryIMU(15);
 
-bool mavlinkConnected = false;
+float mavlinkTime = NAN; // time of last received message
 String mavlinkPrintBuffer;
 
 void processMavlink() {
@@ -40,7 +40,7 @@ void sendMavlink() {
 		sendMessage(&msg);
 	}
 
-	if (!mavlinkConnected) return; // send only heartbeat until connected
+	if (!valid(mavlinkTime)) return; // send only heartbeat until connected
 
 	if (telemetrySlow) {
 		mavlink_msg_extended_sys_state_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg,
@@ -101,7 +101,7 @@ void receiveMavlink() {
 	mavlink_status_t status;
 	for (int i = 0; i < len; i++) {
 		if (mavlink_parse_char(MAVLINK_COMM_0, buf[i], &msg, &status)) {
-			mavlinkConnected = true;
+			mavlinkTime = t;
 			handleMavlink(&msg);
 		}
 	}

flix/parameters.ino

@@ -9,11 +9,13 @@
 extern int channelZero[16], channelMax[16];
 extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
 extern int rcRxPin, voltagePin;
-extern int wifiMode, wifiLongRange, udpLocalPort, udpRemotePort, espnowChannel;
-extern float rcLossTimeout, descendTime;
+extern int wifiMode, wifiLongRange, wifiBroadcast, udpLocalPort, udpRemotePort, espnowChannel;
+extern float rcLossTimeout, descendTime, disarmTilt;
 extern float voltageScale;
 extern LowPassFilter<float> voltageFilter;
 
+#include "config.h"
+
 Preferences storage;
 
 struct Parameter {
@@ -44,6 +46,7 @@ Parameter parameters[] = {
 	{"CTL_Y_RATE_P", &yawRatePID.p},
 	{"CTL_Y_RATE_I", &yawRatePID.i},
 	{"CTL_Y_RATE_D", &yawRatePID.d},
+	{"CTL_Y_RATE_WU", &yawRatePID.windup},
 	{"CTL_Y_RATE_D_A", &yawRatePID.lpf.alpha},
 	{"CTL_R_P", &rollPID.p},
 	{"CTL_R_I", &rollPID.i},
@@ -60,6 +63,15 @@ Parameter parameters[] = {
 	{"CTL_FLT_MODE_1", &flightModes[1]},
 	{"CTL_FLT_MODE_2", &flightModes[2]},
 	// imu
+	{"IMU_MODEL", &imuModel},
+	{"IMU_BUS", &imuBus},
+	{"IMU_PIN_SCK", &imuSckPin},
+	{"IMU_PIN_MISO", &imuMisoPin},
+	{"IMU_PIN_MOSI", &imuMosiPin},
+	{"IMU_PIN_CS", &imuCsPin},
+	{"IMU_PIN_SDA", &imuSdaPin},
+	{"IMU_PIN_SCL", &imuSclPin},
+	{"IMU_PIN_INT", &imuIntPin},
 	{"IMU_ROT_ROLL", &imuRotation.x},
 	{"IMU_ROT_PITCH", &imuRotation.y},
 	{"IMU_ROT_YAW", &imuRotation.z},
@@ -112,6 +124,7 @@ Parameter parameters[] = {
 	{"WIFI_PORT_LOC", &udpLocalPort},
 	{"WIFI_PORT_REM", &udpRemotePort},
 	{"WIFI_LONG_RANGE", &wifiLongRange},
+	{"WIFI_BROADCAST", &wifiBroadcast},
 	// espnow
 	{"ESPNOW_CHANNEL", &espnowChannel},
 	// mavlink
@@ -128,10 +141,12 @@ Parameter parameters[] = {
 	// safety
 	{"SF_RC_LOSS_TIME", &rcLossTimeout},
 	{"SF_DESCEND_TIME", &descendTime},
+	{"SF_DISARM_TILT", &disarmTilt},
 };
 
 void setupParameters() {
 	print("Setup parameters\n");
+	setDefaults();
 	storage.begin("flix");
 	// Read parameters from storage
 	for (auto &parameter : parameters) {

flix/pid.h

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

flix/power.ino

@@ -5,11 +5,11 @@
 
 #include <soc/soc.h>
 #include <soc/rtc_cntl_reg.h>
-#include "lpf.h"
+#include "filter.h"
 #include "util.h"
 
 float voltage = NAN;
-LowPassFilter<float> voltageFilter(0.2);
+LowPassFilter<float> voltageFilter(1);
 int voltagePin = -1;
 float voltageScale = 2;
 

flix/safety.ino

@@ -8,10 +8,12 @@ extern float controlRoll, controlPitch, controlThrottle, controlYaw;
 
 float rcLossTimeout = 1;
 float descendTime = 10;
+float disarmTilt = radians(120);
 
 void failsafe() {
 	rcLossFailsafe();
 	autoFailsafe();
+	tiltFailsafe();
 }
 
 // RC loss failsafe
@@ -36,7 +38,7 @@ void descend() {
 // Allow pilot to interrupt automatic flight
 void autoFailsafe() {
 	static float roll, pitch, yaw, throttle;
-	if (roll != controlRoll || pitch != controlPitch || yaw != controlYaw || abs(throttle - controlThrottle) > 0.05) {
+	if (abs(roll - controlRoll) > 0.05 || abs(pitch - controlPitch) > 0.05 || abs(yaw - controlYaw) > 0.05 || abs(throttle - controlThrottle) > 0.05) {
 		// controls changed and mode switch is not configured
 		if (mode == AUTO && invalid(controlMode)) mode = STAB; // regain control by the pilot
 	}
@@ -45,3 +47,15 @@ void autoFailsafe() {
 	yaw = controlYaw;
 	throttle = controlThrottle;
 }
+
+// Disarm if tilted too much
+void tiltFailsafe() {
+	if (!armed) return;
+	if (mode != STAB) return;
+
+	Vector up = Quaternion::rotateVector(Vector(0, 0, 1), attitude);
+	float tilt = acos(up.z);
+	if (disarmTilt && tilt > disarmTilt) {
+		armed = false;
+	}
+}

flix/util.h

@@ -68,7 +68,7 @@ public:
 class Rate {
 public:
 	float rate;
-	float last = 0;
+	float last = -INFINITY;
 	Rate(float rate) : rate(rate) {}
 
 	operator bool() {

flix/wifi.ino

@@ -17,6 +17,7 @@ const int W_DISABLED = 0, W_AP = 1, W_STA = 2, W_ESPNOW = 3;
 int wifiMode = W_AP;
 
 int wifiLongRange = 0;
+int wifiBroadcast = 0; // 0 - broadcast until connected, 1 - always broadcast
 int udpLocalPort = 14550;
 int udpRemotePort = 14550;
 IPAddress udpRemoteIP = "255.255.255.255";
@@ -58,13 +59,14 @@ void sendWiFi(const uint8_t *buf, int len) {
 		espnow.write(buf, len);
 
 		static Rate discovery(2);
-		if (discovery) espnowBroadcast.write((const uint8_t *)"flix", 4); // broadcast message to help finding this device
+		if (espnow.isEncrypted() && discovery) espnowBroadcast.write((const uint8_t *)"flix", 4); // broadcast message to help finding this device
 		return;
 	}
 
 	if (WiFi.softAPgetStationNum() == 0 && !WiFi.isConnected()) return;
 
-	udp.beginPacket(udpRemoteIP, udpRemotePort);
+	bool broadcast = wifiBroadcast || !(t - mavlinkTime < 5); // broadcast if lost connection
+	udp.beginPacket(broadcast ? IPAddress(255, 255, 255, 255) : udpRemoteIP, udpRemotePort);
 	udp.write(buf, len);
 	udp.endPacket();
 }
@@ -113,7 +115,7 @@ void printWiFiInfo() {
 	} else {
 		print("Mode: Disabled\n");
 	}
-	print("MAVLink connected: %d\n", mavlinkConnected);
+	print("MAVLink connected: %d\n", valid(mavlinkTime));
 }
 
 void configWiFi(int mode, const char *first, const char *second) {

gazebo/flix.h

@@ -9,7 +9,7 @@
 #include "quaternion.h"
 #include "Arduino.h"
 #include "wifi.h"
-#include "lpf.h"
+#include "filter.h"
 
 extern float t, dt;
 extern float controlRoll, controlPitch, controlYaw, controlThrottle, controlMode;
@@ -21,6 +21,9 @@ extern float motors[4];
 Vector gyro, acc, imuRotation;
 Vector accBias, gyroBias, accScale(1, 1, 1);
 LowPassFilter<Vector> gyroBiasFilter(0);
+int imuModel = 1, imuBus = 0;
+int imuSckPin = 0, imuMisoPin = 0, imuMosiPin = 0, imuCsPin = -1, imuIntPin = -1;
+int imuSdaPin = 0, imuSclPin = 0;
 
 // declarations
 void step();
@@ -63,6 +66,7 @@ void failsafe();
 void rcLossFailsafe();
 void descend();
 void autoFailsafe();
+void tiltFailsafe();
 int parametersCount();
 const char *getParameterName(int index);
 float getParameter(int index);

gazebo/simulator.cpp

@@ -23,7 +23,7 @@
 #include "estimate.ino"
 #include "safety.ino"
 #include "log.ino"
-#include "lpf.h"
+#include "filter.h"
 #include "mavlink.ino"
 #include "motors.ino"
 #include "parameters.ino"