c=1
while True:
    akpl_buf = [c,1, 2, 3,4,5,6,7,8,9,0,1, 2, 3,4,5,6,7,8]
    pipe = [0]
    # wait for incoming packet from transmitter
    while not radio.available(pipe):
        time.sleep(10000/1000000.0)

    recv_buffer = []
    radio.read(recv_buffer, radio.getDynamicPayloadSize())
    print recv_buffer
    c = c + 1
    if (c&1) == 0:    # queue a return payload every alternate time
        radio.writeAckPayload(1, akpl_buf, len(akpl_buf))