hmmm....may not be able to support the small board builds.

There are several large values needed internally for computing timing values as well as masking.

Adafruit CircuitPython 7.2.5 on 2022-04-06; Adafruit QT Py M0 with samd21e18
>>> macro_period_us = 0x40000000
OverflowError: long int not supported in this build
>>> mask = 0xFFFFFF00
OverflowError: long int not supported in this build
>>> 

These were taken from the STM Arduino driver and the specifics are not documented elsewhere. So would need to figure out how to re-write this code to accommodate the small builds:

Is it worth using a guard statement when importing to check for large integer support, and raise a custom exception explaining incompatibility instead?

Maybe. The other option here, as suggested by @dhalbert, is to use reduced precision in the math. Just haven't worked out the specifics since there's a bit going on with the computations. But that might be too much of a hack just to accommodate the small int boards?

0x40000000 can be expressed exactly as a float. It's 1073741824, which is 2**30. So you could change

macro_period_us = int(2304 * (0x40000000 / osc_freq)) >> 6
to
macro_period_us = int(2304 * (1073741824.0 / osc_freq)) >> 6
since the division is already a float operation anyway. So this wouldn't lose any precision whether or not you have long ints.

For the 0xFFFFFF00 mask, I think you could shift 8 bits right before you mask, unless ls_byte is initially computed to be a longint.

I can try some of these changes and check it out.

@tekktrik cool. thanks. i think it was some of the lines further down that gave me pause also. and didnt help that these were just translated from other source. i don't think i found any other documentation describing what is being done, which could have also helped to potentially just reimplement in some other way.

neat. this got fixed. @FoamyGuy thanks!