On pyboard:
>>> import pyb
>>> pin = pyb.Pin('A2')
>>> pin
Pin(Pin.cpu.A2, mode=Pin.ALT, pull=Pin.PULL_UP, af=Pin.AF7_USART2)

On many NUCLEO boards:
>>> import pyb
>>> pin = pyb.Pin('A2')
>>> pin
Pin(Pin.cpu.A4, mode=Pin.ANALOG)

On NUCLEO boards (eg NUCLEO_F091RC or L476RG) 'A2' maps to cpu pin A4.

This is because pins.csv has a board pin entry 'A2' for the Arduino analog pin name. Quite a few of the Arduino pin names are the same as the STM32 port names.

I can think of 4 solutions:

1. Remove the Arduino pin names from pins.csv.
2. Prepend the Arduino name with something, eg connector name - CN8_A2
3. Require cpu pins to be entered with a P, eg pyb.Pin('PA2').
4. Require cpu pins to be entered with a cpu. prefix, eg pyb.Pin('cpu.A2').

Options 3 & 4 are most likely to break existing code, although this could be avoided by mapping the short names in the csv file, eg A2,PA2 or A2,cpu.A2, for non NUCLEO ports.

Option 3 may not work for all MCUs as some MCUs don't have a P, just A2, etc.

I am currently using option 2, ie make board pin names unique.

Any suggestions on the best fix?