Custom STM32H743 flight controller based on MicoAir743: sensors work in bare-metal test, but ArduPilot shows RAW_IMU = 0

ArduCopter Copter 4.6
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1

Hello,

I am trying to port ArduPilot to my own custom flight controller based on the STM32H743VIT6, using MicoAir743 as the closest reference board.

My board hardware is:

  • MCU: STM32H743VIT6

  • HSE: 8 MHz

  • USB FS: PA11/PA12

  • LEDs:

    • PE4 = BLUE

    • PE5 = RED

    • PE6 = GREEN

Sensor connections:

  • SPI bus:

    • PD3 = SCK

    • PC3 = MOSI

    • PC2 = MISO

  • IMUs:

    • BMI088 accel CS = PD4

    • BMI088 gyro CS = PD5

    • BMI270 CS = PA15

  • I2C bus:

    • PB10 = SCL

    • PB11 = SDA

  • I2C sensors:

    • LPS22HH barometer

    • LSM303AGR accel/mag

I created custom hwdef.dat and hwdef-bl.dat for my board and built ArduPilot for it.

My problem is:

  • in some builds the board boots and connects to Mission Planner,

  • but RAW_IMU stays at zero,

  • AHRS shows error_rp = 1,

  • roll/pitch/yaw do not react,

  • and barometer detection also seems broken.

In Mission Planner, RAW_IMU.xacc/yacc/zacc/xgyro/ygyro/zgyro remain 0 all the time.

What makes this confusing is that I wrote a separate bare-metal sensor test firmware for the same board, and in that test:

  • BMI088 responds correctly,

  • BMI270 responds,

  • LSM303AGR responds,

  • movement changes the IMU readings,

  • compass changes are also detected.

So the hardware and sensor wiring seem to be correct.

I also noticed that a previously downloaded MicoAir743 arducopter_with_bl.hex appears to be from ArduCopter 4.6.3, while my local builds from current master are 4.8.0-dev, and the generated .hex files differ a lot. Because of that, I am not sure whether I am dealing with:

  • a hwdef mistake,

  • a sensor driver/init issue,

  • a difference between 4.6.3 and current master,

  • or some board-specific detail in MicoAir743 that I missed.

My questions are:

  1. If the sensors work in bare-metal code, what is the most likely reason for RAW_IMU = 0 in ArduPilot?

  2. Is there anything for BMI088/BMI270 on H743 boards that must be configured beyond hwdef.dat / hwdef-bl.dat?

  3. Could a barometer or compass init failure prevent the IMU from becoming usable?

  4. Would it be better to start from a minimal BMI088-only config first and add the other sensors later?

  5. Is there any known-good example for a custom H743 board very close to MicoAir743?

If needed, I can also post my hwdef.dat, hwdef-bl.dat, and exact sensor pin mapping.

Thanks in advance.

If you want, I can also make a shorter, more “forum-style” version, or a more technical one with the exact hwdef lines included.

2

Of course it’s needed!

3

My board hardware is:

  • MCU: STM32H743VIT6

  • HSE: 8 MHz

  • USB FS: PA11/PA12

  • LEDs:

    • PE4 = BLUE

    • PE5 = RED

    • PE6 = GREEN

Sensor connections:

  • SPI bus:

    • PD3 = SCK

    • PC3 = MOSI

    • PC2 = MISO

  • IMUs:

    • BMI088 accel CS = PD4

    • BMI088 gyro CS = PD5

    • BMI270 CS = PA15

  • I2C bus:

    • PB10 = SCL

    • PB11 = SDA

  • I2C sensors:

    • LPS22HH barometer

    • LSM303AGR accel/mag

hwdef-bl_dat.txt (838 Bytes)

hwdef_dat.txt (3.3 KB)