CircuitPython PIO UART pin finder

code.py

# PIO UART pin finder
# modified from an old SPI pin finder, probably _somewhere_ in the Adafruit docs

# PIO UART doesn't require sequential pins, and pins don't have to be associated with a particular peripheral
# But... ValueError: Cannot use GPIO0..15 together with GPIO32..47

import board
import busio
from microcontroller import Pin
import adafruit_pio_uart


def is_pio_uart(tx, rx, cts, rts):
    try:
        p = adafruit_pio_uart.UART(tx, rx, 9600, 8, None, 1, 1, cts, rts)
        p.deinit()
        return True
    except ValueError:
        return False

def get_unique_pins():
    # any combination of 4 pins >= GP32 [GP30]? No in 10.0.0-beta.3
    exclude = ['GP0', 'GP1', 'GP10', 'GP11', 'GP12', 'GP13', 'GP14', 'GP15', 'GP16', 'GP17', 'GP18', 'GP19', 'GP2', 'GP20', 'GP21', 'GP22', 'GP23', 'GP24', 'GP25', 'GP26', 'GP27', 'GP28', 'GP29', 'GP3', 'GP30', 'GP31', 'GP4', 'GP5', 'GP6', 'GP7', 'GP8', 'GP9',]
    pins = [pin for pin in [
        getattr(board, p) for p in dir(board) if p not in exclude]
            if isinstance(pin, Pin)]
    unique = []
    for p in pins:
        if p not in unique:
            unique.append(p)
    return unique


pins = get_unique_pins()
for tx_pin in pins:
    for rx_pin in pins:
        for cts_pin in pins:
            for rts_pin in pins:
                pin_set = {tx_pin, rx_pin, cts_pin, rts_pin}  # set()
                if len(pin_set) < 4:
                    continue
                print(f"tx={tx_pin}, rx={rx_pin}, cts={cts_pin}, rts={rts_pin}", end="\r")
                if is_pio_uart(tx_pin, rx_pin, cts_pin, rts_pin):
                    print(f"tx={tx_pin}, rx={rx_pin}, cts={cts_pin}, rts={rts_pin}")

print(f"Done {' '*50}")