CircuitPython code for converting TCA8418 i2c keyboard matrix to USB

pocketchip_usb.py

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

KEY_MAP = {
    1: Keycode.EQUALS,
    2: Keycode.ONE,
    3: Keycode.TWO,
    4: Keycode.THREE,
    5: Keycode.FOUR,
    6: Keycode.FIVE,
    7: Keycode.SIX,
    8: Keycode.SEVEN,
    9: Keycode.EIGHT,
    10: Keycode.NINE,
    11: Keycode.Q,
    12: Keycode.W,
    13: Keycode.E,
    14: Keycode.R,
    15: Keycode.T,
    16: Keycode.Y,
    17: Keycode.U,
    18: Keycode.I,
    19: Keycode.O,
    20: Keycode.P,
    21: Keycode.A,
    22: Keycode.S,
    23: Keycode.D,
    24: Keycode.F,
    25: Keycode.G,
    26: Keycode.H,
    27: Keycode.J,
    28: Keycode.K,
    29: Keycode.L,
    30: Keycode.ENTER,
    31: Keycode.TAB,
    32: Keycode.Z,
    33: Keycode.X,
    34: Keycode.C,
    35: Keycode.V,
    36: Keycode.B,
    37: Keycode.N,
    38: Keycode.M,
    39: Keycode.UP_ARROW,
    40: Keycode.DOWN_ARROW,
    41: Keycode.ESCAPE,
    43: Keycode.ALT,
    44: Keycode.SPACE,
    45: Keycode.CONTROL,
    46: Keycode.FORWARD_SLASH,
    47: Keycode.RIGHT_SHIFT,


    49: Keycode.LEFT_ARROW,
    50: Keycode.RIGHT_ARROW,
    51: Keycode.LEFT_SHIFT,
    52: Keycode.ZERO,
    53: Keycode.MINUS,
    54: Keycode.BACKSPACE,
    55: Keycode.PERIOD
}
KEY_MAP_FN = {
    1: Keycode.F12,
    2: Keycode.F1,
    3: Keycode.F2,
    4: Keycode.F3,
    5: Keycode.F4,
    6: Keycode.F5,
    7: Keycode.F6,
    8: Keycode.F7,
    9: Keycode.F8,
    10: Keycode.F9,
    18: Keycode.LEFT_BRACKET,
    19: Keycode.RIGHT_BRACKET,
    28: Keycode.QUOTE,
    36: Keycode.GRAVE_ACCENT,
    37: Keycode.POUND,
    38: Keycode.SEMICOLON,
    39: Keycode.PAGE_UP,
    40: Keycode.PAGE_DOWN,
    46: Keycode.BACKSLASH,
    49: Keycode.HOME,
    50: Keycode.END,
    51: Keycode.GUI,
    52: Keycode.F10,
    53: Keycode.F11,
    54: Keycode.BACKSPACE,
    55: Keycode.COMMA,
    
}

i2c = busio.I2C(board.GP5, board.GP4, timeout=1000)    # Pi Pico RP2040

while not i2c.try_lock():
    pass


keyboard = Keyboard(usb_hid.devices)


def i2c_read(register):
    result = bytearray(1)
    i2c.writeto(0x34,bytes([register]))
    i2c.readfrom_into(0x34,result)
    return result[0]

def write(register,value):
    i2c.writeto(0x34,bytes([register,value]))


write(0x1D,0x3F)
write(0x1E,255)
write(0x1F,3)
write(0x01,0x99)

fn_down = False


led_b = digitalio.DigitalInOut(board.LED_B)
led_b.direction = digitalio.Direction.OUTPUT
led_r = digitalio.DigitalInOut(board.LED_R)
led_r.direction = digitalio.Direction.OUTPUT



while True:
    key_event = i2c_read(0x04)
    if key_event > 0:
        key_code = key_event & 0x7F
        key_down = (key_event & 0x80) >> 7 == 1
        if key_code == 42: fn_down = key_down
        print(key_code,fn_down)
        
        led_b.value = not fn_down
        led_r.value = not fn_down
        if key_down:
            if fn_down and key_code in KEY_MAP_FN:
                keyboard.press(KEY_MAP_FN[key_code])
            elif key_code in KEY_MAP:
                keyboard.press (KEY_MAP[key_code])
        else:
            if key_code in KEY_MAP_FN:
                keyboard.release(KEY_MAP_FN[key_code])
            if key_code in KEY_MAP:
                keyboard.release(KEY_MAP[key_code])