id from Pin object

[bitrat]

I seem to recall that the interrupt handler for edges on pins used to take a pin id (typically an int in my case) as an argument, but apparently it now takes the pin object, 'Pin(10)', or whatever...

I've searched in vain for a way to get the id from the Pin object. Do I need to parse the string rep??

[pythoncoder]

On a Pyboard if p is a Pin instance p.name() returns the CPU pin name:

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>>> import machine
>>> p = machine.Pin('Y1', machine.Pin.IN)
>>> p.name()
'C6'

Alternatively you could maintain a dict of names:

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pins = {}
name = 'Y1'
p = machine.Pin(name, machine.Pin.IN)
pins[id(p)] = name

which would enable retrieval of the name you used to instantiate the pin.

[bitrat]

Hi Peter,

thanks for this. Unfortunately, on my board, there's no

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Pin.name()

The dictionary approach is against my principles, in that it introduces more than one record of the same information and moves locally accessible data into a global scope.

I'm using ints as pin names (eg: 'GPIO14' is 14). I'll investigate when I have time, but from memory the outdated MP I was using earlier was passing that int to the pin's interrupt handler callback, not the whole Pin object.

It seems reasonable to pass the object, but it's extremely annoying to have no way to easily extract the integer. The object's __str__() method prints, for example, 'Pin(14)' where I just want 14. I use the one liner:

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 id = int(''.join(char for char in s if char.isdigit()))

to get WIW, but ...meh. None of this is happening in the actual interrupt handler (which just schedules a user space handler) but it's the kind of finagling that sucks cycles and introduces bugs.

All I'm doing with the pin identifier is sending it to another device in a UDP message, and I just want the number of the pin, not the whole string.

I'm planning to build MP from source so I'll probably add a method for this in C. Maybe you'll get a PR for it.