On the stm32h7b3i-dk port, how do I use the spi and gpio pins?

[4riceotter]

Hi, All,

With @jimmo and @dpgeorge 's help, 

 https://github.com/orgs/micropython/discussions/11584

I was able to to get started with micropython on the stm32h7b3i-dk board. Borrowing from some examples from the nucleo-stm32h743i blog,

https://blog.csdn.net/weixin_39861920/article/details/110035700?

I got the following working to blink the two LED's on board with a timer:

tm = pyb.Timer(6, freq=2)
tm.callback(lambda t: pyb.LED(1).toggle())
tm2 = pyb.Timer(7,freq=5)
tm2.callback(lambda t: pyb.LED(2).toggle())

or the User switch:

sw=pyb.Switch()
sw()
while 1:
    if sw():
        pyb.LED(2).on()
    else:
        pyb.LED(2).off()

But how do I use the on-board GPIO and SPI pins? With my previous micropython experience on the Raspberry Pi Pico, the micropython doc tells me which pins I can use for the SPI ports, and all available GPIO pins are addressable by their names. I tried a few guesses on the GPIO pin names, but they returned with errors. Any ideas?

Your suggestions and advice will be greatly appreciated.  Thanks in advance!

Benjamin

[jimmo]

@4riceotter What have you tried so far?

https://docs.micropython.org/en/latest/library/machine.Pin.html
https://docs.micropython.org/en/latest/library/machine.SPI.html

On stm32, you can specify pins either by their CPU name (e.g. "A6" (Edit: sorry, wrote PA6 earlier)) or their board name (depends on the board, not many defined for this particular board, see https://github.com/micropython/micropython/blob/master/ports/stm32/boards/STM32H7B3I_DK/pins.csv).

[4riceotter]

This is what my attempts should look like.

[jimmo]

Sorry yes that was a typo, I should have written A6 not PA6.

FYI you can list the known pins using:

>>> dir(machine.Pin.cpu)
['__class__', '__name__', '__bases__', '__dict__', 'A0', 'A1', 'A10', 'A11', 'A12', 'A13', 'A14', 'A15', 'A2', 'A3', 'A4', 'A5', 'A6', 'A7', 'A8', 'A9', 'B0', 'B1', 'B10', 'B11', 'B12', 'B13', 'B14', 'B15', 'B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B9', 'C0', 'C1', 'C10', 'C11', 'C12', 'C13', 'C2', 'C3', 'C4', 'C5', 'C6', 'C7', 'C8', 'C9', 'D2']
>>> dir(machine.Pin.board)
['__class__', '__name__', '__bases__', '__dict__', 'LED_BLUE', 'LED_GREEN', 'LED_RED', 'LED_YELLOW', 'MMA_AVDD', 'MMA_INT', 'SD', 'SD_CK', 'SD_CMD', 'SD_D0', 'SD_D1', 'SD_D2', 'SD_D3', 'SD_SW', 'SW', 'USB_DM', 'USB_DP', 'USB_ID', 'USB_VBUS', 'X1', 'X10', 'X11', 'X12', 'X17', 'X18', 'X19', 'X2', 'X20', 'X21', 'X22', 'X3', 'X4', 'X5', 'X6', 'X7', 'X8', 'X9', 'Y1', 'Y10', 'Y11', 'Y12', 'Y2', 'Y3', 'Y4', 'Y5', 'Y6', 'Y7', 'Y8', 'Y9']

Any of those results can be passed to machine.Pin (i.e. machine.Pin("X11"), or you can use machine.Pin.cpu.A6 or machine.Pin.board.X11 to access the pin object directly (this is my preferred way, but only supported currently on stm32/rp2).

Looking at the SPI... it looks like this board definition is missing the configuration of the SPI peripherals... (argh). If you want to make this work, I suggest looking at e.g. https://github.com/micropython/micropython/blob/master/ports/stm32/boards/PYBD_SF2/mpconfigboard.h#L131
You don't need to define the NAME, only the default pins. Once that's done then the SPI peripheral with that ID will be available for machine.SPI / pyb.SPI (unless you specifically need the latter, use the former).

[robert-hh]

but only supported currently on stm32/rp2

As well on mimxrt and samd.

[4riceotter]

@jimmo Great, I'll try that tomorrow.
BTW, I did not know about the dir() function. Thanks for pointing that out!

Benjamin

[4riceotter]

Hi,

I have been able to clone the micropython project and successfully compiled with BOARD=STM32H7B3I_DK.  REPL works, so I proceeded with adding the lines for spi in the file  mpconfigboard.h, using the pins on the STMod+ connector:

#define MICROPY_HW_SPI2_NSS (pin_A11)
#define MICROPY_HW_SPI2_SCK (pin_A12)
#define MICROPY_HW_SPI2_MISO (pin_C2)
#define MICROPY_HW_SPI2_MOSI (pin_C3)

Micropython recompiles and REPL still works. But when I tried to instantiate spi I keep getting errors:

from machine import SPI
sp = SPI(baudrate=1000000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB)
Warning: SPI(-1, ...) is deprecated, use SoftSPI(...) instead
Traceback (most recent call last):
File "", line 1, in
ValueError: must specify all of sck/mosi/miso

sp = SPI(2, baudrate=1000000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB)
Traceback (most recent call last):
File "", line 1, in
ValueError: SPI(2) doesn't exist

regardless what value I used for the 1st argument. The example from pyb.SPI also failed. How can I tell if SPI is defined correctly, and what argument should I use for the instantiation?

Thanks again for your help!

Benjamin