Experiment: Read raw keys from an USB number pad

hidreader.py

# See this for creating a udev rule to avoid the need to be root:
# https://peterkieser.com/2013/07/30/accessing-usb-devices-as-non-root-writing-udev-rules-the-easy-way/

# SUBSYSTEM=="hidraw", ATTRS{idVendor}=="1241", ATTRS{idProduct}=="1503", GROUP="mitch", MODE="0660"

keymap = {
    42: 'BACKSPACE',
    83: 'NUMLOCK',
    84: '/',
    85: '*',
    86: '-',
    87: '+',
    88: 'ENTER',
    99: 'DEL',
    89: '1',
    90: '2',
    91: '3',
    92: '4',
    93: '5',
    94: '6',
    95: '7',
    96: '8',
    97: '9',
    98: '0',
}

def resolve(byte):
    if byte in keymap:
        return keymap[byte]
    return byte

def hidraw_reader(filename):
    with open(filename, "rb") as f:
        while True:
            event = f.read(8)
            # We don't care about the first 2 bytes
            bytes = [ord(byte) for byte in event][2:]
            bytes = filter(lambda x: x > 0, bytes)
            if sum(bytes) == 6:
                # ! Too many keys pressed
                pass
            elif sum(bytes) > 0:
                yield map(resolve, bytes)

if __name__ == '__main__':
    for keys in hidraw_reader("/dev/hidraw1"):
        print(keys)