Use Emulation to Run RP2 PIO Code on Other Ports

The RP2 chip's PIO peripheral is a powerful piece of hardware capable of performing tasks that might otherwise require very fast bit-banging code, but it's also quite difficult to validate the correctness of a complicated PIO program as this code can then "only" be run on real hardware.

I'm planning to implement a library that's API-compatible with the rp2.StateMachine interface, to allow other ports to run PIO programs via emulation. I don't know if this can ever allow practical real-time I/O on any of the microcontroller ports; my primary use-case is to enable using the unix port to run test cases involving PIO functionality.

Given that initial goal, I intend to implement this by wrapping the rp2040-pio-emulator python package. A later stab at this idea might re-implement it in C later, if someone can figure out a path to doing this in real-time on microcontroller hardware.

Start by reviewing the rp2.StateMachine interface and the rp2040-pio-emulator package named in the issue. Determine the compatibility surface and how the Unix port could exercise PIO test cases. Done means a usable API-compatible emulation library is available for those tests.