import struct


def checksum(data: bytes) -> bytes:
	ck_a = 0
	ck_b = 0
	for i in range(len(data)):
		ck_a = (ck_a + data[i]) & 0xFF
		ck_b = (ck_b + ck_a) & 0xFF

	return struct.pack("BB", ck_a, ck_b)

def frame_create(msg_class: int, msg_id: int, payload: bytes) -> bytes:
	hdr = b'\xb5\x62'
	frame = struct.pack('B', msg_class)
	frame += struct.pack('B', msg_id)
	frame += struct.pack('<H', len(payload))
	frame += payload
	check = checksum(frame)

	return hdr + payload + check


if __name__ == "__main__":
	result = frame_create(1, 2, b'Hallo')
	print(result)