Prometheus FC is a custom ArduPilot hardware definition that transforms a generic DevEBox STM32H743VIT6 V3.0 development board into a fully functional, high-performance flight controller with full dual-sensor redundancy.
| Component | Details |
|---|---|
| MCU | STM32H743VIT6 @ 480MHz, 2MB Flash, 1MB RAM |
| Board | DevEBox STM32H743VIT6 V3.0 (LQFP100) |
| Crystal | 25MHz HSE |
| Board ID | 7121 |
| Sensor | Interface | Pins | Status |
|---|---|---|---|
| IMU 1 | BMI160 on SPI1 | SCK=PA5, MISO=PA6, MOSI=PD7, CS=PB5 | ✅ Working |
| IMU 2 | BMI160 on SPI4 | SCK=PE12, MISO=PE13, MOSI=PE14, CS=PD4 | ✅ Working (clone chip, ID=0xD3) |
| Baro 1 | BMP280 on SPI1 | Shared SPI1 bus, CS=PB12 | ✅ Working |
| Baro 2 | BMP280 on SPI4 | Shared SPI4 bus, CS=PB13 | ✅ Working |
| Compass 1 | External via I2C1 | SCL=PB6, SDA=PB7 | ✅ Working |
| Compass 2 | External via I2C2 | SCL=PB10, SDA=PB11 | ✅ Working |
| GPS 1 | u-blox via USART1 | TX=PA9, RX=PA10 | ✅ 3D Fix, 9 sats |
| GPS 2 | u-blox via USART6 | TX=PC6, RX=PC7 | ✅ 3D Fix, 8 sats |
| RC Receiver | FSIA10B iBUS via UART4 | RX=PB8 | ✅ Working |
| Serial | UART | TX Pin | RX Pin | Default Use |
|---|---|---|---|---|
| SERIAL0 | OTG1 (USB) | PA11 | PA12 | MAVLink / GCS |
| SERIAL1 | USART1 | PA9 | PA10 | GPS 1 |
| SERIAL2 | USART2 | PD5 | PD6 | MAVLink2 (companion) |
| SERIAL3 | USART3 | PD8 | PD9 | Telemetry |
| SERIAL4 | UART4 | PB9 | PB8 | RC Input (iBUS/SBUS) |
| SERIAL5 | USART6 | PC6 | PC7 | GPS 2 |
| SERIAL6 | UART7 | PE8 | PE7 | Debug console |
| SERIAL7 | UART8 | PE1 | PE0 | Spare |
| PWM | Timer | Pin | Use |
|---|---|---|---|
| PWM1 | TIM4_CH1 | PD12 | Motor 1 |
| PWM2 | TIM4_CH2 | PD13 | Motor 2 |
| PWM3 | TIM4_CH3 | PD14 | Motor 3 |
| PWM4 | TIM4_CH4 | PD15 | Motor 4 |
DShot300 recommended (MOT_PWM_TYPE = 6).
| Function | Pin | GPIO |
|---|---|---|
| Bootloader LED | PA1 | — |
| Status LED 0 (synced to buzzer) | PE2 | GPIO(90) |
| Status LED 1 | PE3 | GPIO(91) |
| Status LED 2 | PB0 | GPIO(92) |
| Buzzer | PE4 | GPIO(80) |
The PE2 LED is synced to the buzzer — it flashes in sync with all buzzer patterns.
| Function | Pin |
|---|---|
| Voltage sense | PA2 (ADC1) |
| Current sense | PA3 (ADC1) |
Scales: HAL_BATT_VOLT_SCALE 11.0, HAL_BATT_CURR_SCALE 11.0
| Signal | Pin |
|---|---|
| CAN1_RX | PD0 |
| CAN1_TX | PD1 |
Requires external CAN transceiver (e.g. SN65HVD230).
Two patches must be applied to ArduPilot source before building:
Problem: BMI160 powers up in I2C mode. The driver attempted a SOFTRESET write before doing the SPI wakeup sequence, so the write failed and the chip was never switched to SPI mode. Also, the SPI4 BMI160 is a clone chip returning chip ID 0xD3 instead of the official 0xD1.
Fix 1 - Add SPI wakeup BEFORE the init loop in _hardware_init(): uint8_t v; for (uint8_t wakeup = 0; wakeup < 10; wakeup++) { _dev->read_registers(0x7F, &v, 1); hal.scheduler->delay(5); } hal.scheduler->delay(20);
Fix 2 - Accept clone chip ID 0xD3 alongside official 0xD1: #define BMI160_CHIPID 0xD1 #define BMI160_CHIPID2 0xD3 // clone/variant (common on Chinese boards) // Change chip ID check to: if (v != BMI160_CHIPID && v != BMI160_CHIPID2) {
Fix - Sync LED to buzzer: In hwdef.dat: define HAL_BUZZER_LED_PIN 90 In Buzzer.cpp: Add GPIO write to HAL_BUZZER_LED_PIN alongside buzzer pin writes.
git clone --recurse-submodules https://github.com/ArduPilot/ardupilot.git
cd ardupilot
cp -r "Prometheus-FC" libraries/AP_HAL_ChibiOS/hwdef/
# Apply firmware patches (see above)
./waf configure --board Prometheus-FC
./waf copter
Via bootloader (USB, recommended): python Tools/scripts/uploader.py --port /dev/ttyACM0 build/Prometheus-FC/bin/arducopter.apj
Via DFU (first flash only - hold BOOT0 while plugging USB): sudo dfu-util -a 0 --dfuse-address 0x08020000 -D arducopter.bin
- Use the B/S port (iBUS output) on FSIA10B — NOT the individual PWM ports
- Connect B/S signal wire to PB8 (UART4_RX)
- Connect 5V and GND to receiver
- Bind receiver to FSi6X (solid LED = bound)
- Set: SERIAL4_PROTOCOL=23, RC_PROTOCOLS=32 (iBUS)
This project is for educational and DIY purposes. The STM32H743 runs on 3.3V logic. Ensure all peripherals are 3.3V compatible or use level shifters.