rawhid in python

keymap.c

#include <string.h>

// This function is called when a packet is received on the raw HID interface.
// `length` will always be the size of the output (host to device) report in bytes - 32 in current QMK, but will eventually be raised to 64.
// Thus, if you wish to send variable length data, you should send the length along with the payload, splitting across multiple reports
// if needed, and handle the parsing yourself.
//
// In this simple example, we check that the first byte of the received data is the ASCII character 'A',
// in which case we respond with 'B' and toggle the backlight.
void raw_hid_receive(uint8_t *data, uint8_t length) {
    uint8_t response[RAW_EPSIZE];
    memset(response, 0, RAW_EPSIZE);
    response[0] = 'B';

    if(data[0] == 'A') {
        raw_hid_send(response, RAW_EPSIZE);

        backlight_toggle();
    }
}

rawhid.py

#!/usr/bin/env python3

# NOTE: There are two HID libraries in Python: pyhidapi (https://pypi.org/project/hid/) and cython-hidapi (https://pypi.org/project/hidapi/).
#       Both have similar, but not quite compatible, APIs. This example code uses pyhidapi.

import sys
import hid

vendor_id  = 0x4335
product_id = 0x0002

usage_page = 0xFF60
usage      = 0x61

def get_raw_hid_interface():
    device_interfaces = hid.enumerate(vendor_id, product_id)
    raw_hid_interfaces = [i for i in device_interfaces if i['usage_page'] == usage_page and i['usage'] == usage]

    if len(raw_hid_interfaces) == 0:
        return None

    interface = hid.Device(path=raw_hid_interfaces[0]['path'])

    print("Manufacturer: %s" % interface.manufacturer)
    print("Product: %s" % interface.product)

    return interface

def send_raw_packet(data):
    interface = get_raw_hid_interface()

    if interface is None:
        print("No device found")
        sys.exit(1)

    request_data = [0x00] * 33 # First byte is Report ID
    request_data[1:len(data) + 1] = data
    request_packet = bytes(request_data)

    print("Request:")
    print(request_packet)

    try:
        interface.write(request_packet)

        response_packet = interface.read(32, timeout=1000)

        print("Response:")
        print(response_packet)
    finally:
        interface.close()

if __name__ == '__main__':
    send_raw_packet([
        0x41
    ])