Custom ArduPilot Hardware Definition, Bootloader, Firmware, and Configuration for the DevEBox STM32H743VIT6 V3.0 Flight Controller with Dual-Sensor Redundancy.
Prometheus FC turns a low-cost, high-performance generic DevEBox STM32H743VIT6 V3.0 development board into a flight controller running ArduCopter V4.8.0-dev.
Unlike off-the-shelf commercial flight controllers with soldered onboard sensors, this design gives you full control over external sensor wiring with complete dual-bus isolation:
- Dual IMU Redundancy: 2× BMI160 on isolated SPI buses (SPI1 + SPI4)
- Dual Barometer Redundancy: 2× BMP280 on isolated SPI buses (SPI1 + SPI4)
- Dual Compass Support: 2× External Compasses on independent I2C buses (I2C1 + I2C2)
- Dual GPS Support: 2× u-blox GPS modules on dedicated serial ports (USART1 + USART6)
- Dedicated Motor DMA: TIM4 motor outputs (PD12–PD15) with dedicated DMA streams to prevent GPS UART collisions
- Full Dataflash Logging: Onboard MicroSD card slot via 4-bit SDMMC1
| Top View (DevEBox + Sensors) | Front View | Mounted on Drone Frame |
|---|---|---|
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 |
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| Parameter | Specification |
|---|---|
| Microcontroller | STM32H743VIT6 (ARM Cortex-M7 @ 480 MHz, double-precision FPU) |
| Flash Memory | 2048 KB (128 KB Bootloader + 1664 KB Firmware + 256 KB Flash Storage) |
| RAM | 1024 KB SRAM + 64 KB ITCM RAM |
| Oscillator | 25 MHz HSE Crystal (Y2 on board) |
| ArduPilot Board ID | 7121 (AP_HW_DevEBoxH743) |
| USB Interface | USB-C (OTG_FS, PA11 / PA12) |
| SD Storage | MicroSD slot connected to SDMMC1 (4-bit FatFS logging) |
| Parameter Storage | Internal Flash Pages 14–15 (32 KB persistent EEPROM emulation) |
Prometheus FC/
├── README.md # This documentation
├── hwdef.dat # ArduPilot ChibiOS hardware definition
├── hwdef-bl.dat # ArduPilot bootloader hardware definition
├── DevEBoxH743_Prometheus_FC_Pinout_Guide.txt # Complete wire-by-wire connection guide
│
├── media/ # Flight test videos, hardware photos, and 3D CAD renders
│ ├── FC_topview.jpeg # Hardware top view
│ ├── FC_FrontView.jpeg # Hardware front connector view
│ ├── FC_on_F450frame.jpeg # Flight controller mounted on quadcopter frame
│ ├── 1st_flight_prometheusFC_withstock_pixhawkPIDs.mp4 # Maiden flight test video
│ ├── 2nd_flightTest_loitermode_gpsLock_after_MinorPIDs_tuning.mp4 # Loiter mode GPS lock flight test
│ └── PrometheusFC_kicad3d.mp4 # KiCad 3D CAD animation
│
├── bootloader/ # Pre-compiled bootloader binaries
│ ├── Prometheus-FC_bl.bin # Raw binary (for DFU / ST-Link at 0x08000000)
│ └── Prometheus-FC_bl.hex # Intel HEX (for STM32CubeProgrammer)
│
├── firmware/ # Pre-compiled ArduCopter firmware
│ ├── arducopter.apj # ArduPilot package (for Mission Planner / QGC / uploader.py)
│ ├── arducopter.bin # Raw binary (for DFU at 0x08020000)
│ └── arducopter_with_bl.hex # Complete chip image (Bootloader + Firmware combined)
│
├── parameters/ # Tested vehicle configuration files
│ └── prometheus_s500_tested.param # 1004 calibrated parameters from real flight testing
│
├── patches/ # ArduPilot source tree patches
│ ├── 0001-AP_InertialSensor_BMI160.patch # SPI 0x7F wakeup sequence & clone chip ID (0xD3) support
│ ├── 0002-AP_Notify_Buzzer_LED_sync.patch # Status LED (PE2) synchronization with buzzer tones
│ └── 0003-board_types_7121.patch # Registration of Board ID 7121 in board_types.txt
│
└── scripts/ # Automation and diagnostic tools
├── install.sh # One-command installer: copies hwdef & applies patches
├── flash_bootloader.sh # Flashes bootloader via dfu-util or st-flash
└── deep_sensor_check.py # Live MAVLink verification script for all dual sensors
Real flight footage and CAD design demonstrations recorded from the test vehicle:
| Download for Preview | Flight Details & Technical Highlights |
|---|---|
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1. Flight Test 2: Autonomous Loiter Mode & GPS Lock • Test Objective: Autonomous position-hold in Loiter mode following minor rate PID tuning. • Results: Rock-solid GPS lock, zero horizontal drift, stable altitude hold, and smooth dual-sensor EKF3 fusion. • Footage: media/2nd_flightTest_loitermode_gpsLock_after_MinorPIDs_tuning.mp4 (20s, 60fps) |
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2. Flight Test 1: Maiden Hover with Stock Pixhawk PIDs • Test Objective: Initial takeoff and hover test right after firmware flashing. • Results: Safe takeoff and baseline hover stability operating on default multicopter PID parameters. • Footage: media/1st_flight_prometheusFC_withstock_pixhawkPIDs.mp4 (10s, 30fps) |
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3. KiCad 3D Hardware CAD Board Design • Design: Custom PCB carrier board for the DevEBox STM32H743 module. • Results: 3D CAD visualization showing component placement, header pin routing, and sensor bus layout. • Footage: media/PrometheusFC_kicad3d.mp4 (10s, 60fps) |
All sensors listed below have been verified in hardware and flight-tested:
| Subsystem | Hardware | Bus / Peripheral | Pins | Status | Notes |
|---|---|---|---|---|---|
| IMU 1 | Bosch BMI160 | SPI1 | SCK: PA5, MISO: PA6, MOSI: PD7, CS: PB5 | ✅ Working | Primary IMU, ROTATION_ROLL_180 |
| IMU 2 | Bosch BMI160 | SPI4 | SCK: PE12, MISO: PE13, MOSI: PE14, CS: PD4 | ✅ Working | Secondary IMU, clone chip (ID 0xD3) |
| Baro 1 | Bosch BMP280 | SPI1 | Shared SPI1 bus, CS: PB12 | ✅ Working | Primary Baro |
| Baro 2 | Bosch BMP280 | SPI4 | Shared SPI4 bus, CS: PB13 | ✅ Working | Secondary Baro |
| Compass 1 | External HMC5883L/QMC5883L | I2C1 | SCL: PB6, SDA: PB7 | ✅ Working | Primary Compass |
| Compass 2 | External HMC5883L/QMC5883L | I2C2 | SCL: PB10, SDA: PB11 | ✅ Working | Secondary Compass |
| GPS 1 | u-blox M8N | USART1 (SERIAL1) | TX: PA9, RX: PA10 | ✅ Working | 115200 baud, 3D Fix |
| GPS 2 / Telem | u-blox M8N / Aux | USART6 (SERIAL5) | TX: PC6, RX: PC7 | ✅ Working | 115200 baud (or configurable for MAVLink) |
| Companion | Radxa Cubie A7S | USART2 (SERIAL2) | TX: PD5, RX: PD6 | ✅ Working | MAVLink2 link, 115200 baud |
| Telemetry | Radio / LoRa | USART3 (SERIAL3) | TX: PD8, RX: PD9 | ✅ Working | MAVLink2, 57600 baud |
| RC Receiver | FlySky FS-iA10B (iBUS) | UART4 (SERIAL4) | RX: PB8, TX: PB9 | ✅ Working | Serial RC Input (SERIAL4_PROTOCOL=23) |
| Motors 1–4 | BLHeli_S / PWM ESCs | TIM4 (PWM 1–4) | PD12, PD13, PD14, PD15 | ✅ Working | TIM4 with isolated DMA stream |
| Battery Volt | Voltage Divider | ADC1 | PA2 (ADC1_IN14) | ✅ Working | Scale: 11.0 (HAL_BATT_VOLT_SCALE) |
| Battery Curr | Current Shunt Sensor | ADC1 | PA3 (ADC1_IN15) | ✅ Working | Scale: 11.0 (HAL_BATT_CURR_SCALE) |
| Status LEDs | External LEDs | GPIO | LED0: PE2 (90), LED1: PE3 (91), LED2: PB0 (92) | ✅ Working | Arming / GPS / Status indication |
| Buzzer | Active Buzzer | GPIO | PE4 (GPIO 80) | ✅ Working | PE2 LED flashes in sync with buzzer |
| Bootloader LED | Onboard D2 LED | GPIO | PA1 | ✅ Working | Active LOW blink during boot |
| CAN Bus | CAN Transceiver (SN65HVD230) | CAN1 | RX: PD0, TX: PD1 | ✅ Ready | HAL_NUM_CAN_IFACES=1 |
| MicroSD | Onboard TF Card Slot | SDMMC1 | PC8, PC9, PC10, PC11, PC12, PD2 | ✅ Working | 4-bit high-speed SDMMC FatFS logging |
In the STM32H743, DMA streams are multiplexed across peripherals. In default builds without timer stream isolation:
- The Conflict:
TIM4_UP(motor outputs PD12–PD15) shares DMA Stream(2,7)withUSART1_TX(GPS1) andUSART6_TX(GPS2). - The Symptom: Continuous high-baud GPS serial transmission preempts or starves the motor DMA channel, corrupting DShot pulses and preventing motors from spinning.
- The Solution in
hwdef.dat:This forces the ChibiOS DMA allocator to giveDMA_NOSHARE SPI1* SPI4* TIM4*TIM4_UPits own dedicated, unshared stream (DMA_STREAM_ID(2,3)), guaranteeing jitter-free motor output.
Standard upstream ArduPilot requires three minor patches to run on this hardware:
-
patches/0001-AP_InertialSensor_BMI160.patch:- Problem A: The BMI160 powers up in I2C mode by default. The driver previously issued a
SOFTRESETbefore switching to SPI mode, causing the initial write to fail in I2C mode. The patch performs 10 dummy reads of register0x7Fbefore and after reset to force the chip into SPI mode. - Problem B: Many readily available BMI160 breakout modules use clone or variant silicon returning chip ID
0xD3instead of the official Bosch0xD1. The patch accepts both0xD1and0xD3.
- Problem A: The BMI160 powers up in I2C mode by default. The driver previously issued a
-
patches/0002-AP_Notify_Buzzer_LED_sync.patch:- Drives
HAL_BUZZER_LED_PIN(GPIO 90 / PE2) in unison with buzzer signals so the external status LED flashes in sync with all ArduPilot audio tunes and warning beeps.
- Drives
-
patches/0003-board_types_7121.patch:- Registers
AP_HW_DevEBoxH743 7121inTools/AP_Bootloader/board_types.txtso the bootloader generator identifies the board correctly.
- Registers
-
Clone ArduPilot:
git clone --recurse-submodules https://github.com/ArduPilot/ardupilot.git cd ardupilot -
Run the installer from this repository:
/path/to/Prometheus-FC/scripts/install.sh . -
Configure and compile:
./waf configure --board Prometheus-FC ./waf copter
The built firmware will be generated at
build/Prometheus-FC/bin/arducopter.apj.
-
Copy
hwdef.dat,hwdef-bl.dat, andREADME.mdto ArduPilot:mkdir -p libraries/AP_HAL_ChibiOS/hwdef/Prometheus-FC cp /path/to/Prometheus-FC/hwdef*.dat libraries/AP_HAL_ChibiOS/hwdef/Prometheus-FC/ -
Apply the three patches:
patch -p1 < /path/to/Prometheus-FC/patches/0001-AP_InertialSensor_BMI160.patch patch -p1 < /path/to/Prometheus-FC/patches/0002-AP_Notify_Buzzer_LED_sync.patch patch -p1 < /path/to/Prometheus-FC/patches/0003-board_types_7121.patch
-
Configure and build:
./waf configure --board Prometheus-FC ./waf copter
If your DevEBox board has never run ArduPilot before, install the custom bootloader:
- Hold the BOOT0 button on the DevEBox while plugging the USB-C cable into your computer.
- Verify the board appears in DFU mode:
lsusb | grep 0483:df11 - Flash the bootloader using the included script:
(Or using an ST-Link:
./scripts/flash_bootloader.sh dfu
./scripts/flash_bootloader.sh stlink) - Unplug and reconnect USB normally. The onboard D2 LED (PA1) will blink rapidly, indicating the bootloader is waiting for firmware.
Once the bootloader is installed, flash firmware directly over USB without pressing any buttons:
-
Using the pre-compiled binary:
python3 /path/to/ardupilot/Tools/scripts/uploader.py --port /dev/ttyACM0 firmware/arducopter.apj
-
Using Ground Control Stations: In QGroundControl or Mission Planner, select Custom Firmware and load
firmware/arducopter.apj. -
Direct DFU (No bootloader required): Hold BOOT0 while plugging in USB, then run:
sudo dfu-util -a 0 --dfuse-address 0x08020000 -D firmware/arducopter.bin
-
Full Chip Erase & Flash (ST-Link / STM32CubeProgrammer): Flash
firmware/arducopter_with_bl.hexdirectly starting at address0x08000000.
The repository includes a complete dump of 1004 calibrated parameters from an active S500 quadcopter (58 logged flights):
- Frame Class & Type:
FRAME_CLASS = 1(Quadcopter),FRAME_TYPE = 1(X-Frame) - Motor Protocols:
MOT_PWM_TYPE = 5(DShot300) or0(Normal PWM) /2(OneShot125) - Disarm Idle Output:
MOT_SAFE_DISARM = 1(sends continuous idle signal when disarmed so ESCs initialize reliably) - Serial Protocols:
SERIAL1_PROTOCOL = 5(GPS1, USART1, 115200)SERIAL2_PROTOCOL = 2(MAVLink2 companion, USART2, 115200)SERIAL3_PROTOCOL = 2(MAVLink2 telemetry, USART3, 57600)SERIAL4_PROTOCOL = 23(RC Input iBUS, UART4, 115200)SERIAL5_PROTOCOL = 5(GPS2 / Aux, USART6, 115200)
- Battery Monitor:
BATT_MONITOR = 4(Analog Voltage and Current), Pin 14 (Volt), Pin 15 (Curr)
To restore all parameters via MAVProxy / pymavlink:
param load parameters/prometheus_s500_tested.paramTo inspect live dual-sensor streams, attitude convergence, and system health over MAVLink, run:
python3 scripts/deep_sensor_check.pyThis script queries both BMI160 IMUs, both BMP280 barometers, both compasses, battery ADC, and EKF3 attitude output and prints a formatted JSON diagnostic summary.
For wire-by-wire color coding, pin numbers, breakout board connections, and motor wiring diagrams, consult: 📄 DevEBoxH743_Prometheus_FC_Pinout_Guide.txt
- This project is licensed under the GNU General Public License v3.0 (GPLv3), matching ArduPilot.
- Disclaimer: This hardware definition and firmware are provided for DIY and educational drone development. Ensure all connected peripherals use 3.3V logic levels. Always perform bench testing without propellers before flight.