FootSwitch.py for Raspberry Pi Pico with CircuitPython

FootSwitch.py

# FootSwitch.py for Raspberry Pi Pico with CircuitPython
# Copyright 2024 (c) Koichi OKADA. All right reserved.
# This script is distributed under the MIT license.

import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode
import time
import board
import digitalio

###############################################################################
# Configurations

# key mapping for GPIO.
# Max 28 keys, because GPIO of Raspberry Pi Pico is GP0-GP28.
KeyMap = [
    Keycode.LEFT_CONTROL,
    Keycode.LEFT_SHIFT,
    Keycode.SPACE,
    Keycode.B,
    Keycode.E,
    Keycode.F,
    Keycode.G,
    Keycode.ONE,
    Keycode.TWO,
    Keycode.THREE,
    Keycode.FOUR,
    Keycode.FIVE,
]

# deadtime [ns] for anti-chattering
deadtime = 1000**3 // 24

# wait [s] for 1 loop
wait = 0.001

# Debug level
debug = 0

###############################################################################
# Initialize

KeyStat = [0] * len(KeyMap)
Last = [0] * len(KeyMap)

IO = [
    board.GP0,
    board.GP1,
    board.GP2,
    board.GP3,
    board.GP4,
    board.GP5,
    board.GP6,
    board.GP7,
    board.GP8,
    board.GP9,
    board.GP10,
    board.GP11,
    board.GP12,
    board.GP13,
    board.GP14,
    board.GP15,
    board.GP16,
    board.GP17,
    board.GP18,
    board.GP19,
    board.GP20,
    board.GP21,
    board.GP22,
    board.GP23,
    board.GP24,
    board.GP25,
    board.GP26,
    board.GP27,
    board.GP28,
]

gp = [None] * len(KeyMap)

kbd = Keyboard(usb_hid.devices)

for i in range(len(KeyMap)):
    gp[i] = digitalio.DigitalInOut(IO[i])
    gp[i].switch_to_input(pull=digitalio.Pull.UP)

led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT

t0 = t1 = t2 = t3 = time.monotonic_ns()
step = 0

###############################################################################
# main loop

while True:
    t = t2 = time.monotonic_ns()
    for i, io in enumerate(gp):
        stat = not io.value
        if stat != KeyStat[i] and deadtime < t - Last[i]:
            Last[i] = t
            KeyStat[i] = 0 if KeyStat[i] else 1
            kbd.press(KeyMap[i]) if KeyStat[i] else kbd.release(KeyMap[i])
    led.value = sum(KeyStat)
    t3 = t1
    t1 = time.monotonic_ns()
    step += 1
    
    if debug:
        if 1 < debug:
            print(f"[{time.monotonic_ns()}, {KeyStat}],")
        if (step == 3000):
            print(f"{step}, {t2 - t1}")
            break
        
    wait1 = wait - (time.monotonic_ns() - t2) / 1000**3
    wait1 = wait1 if 0 < wait1 else 0
    time.sleep(wait1)