#
# hello.HC-SR04.py
#
# HC-SR04 sonar hello-world
#    hello.HC-SR04.py serial_port
#
# Neil Gershenfeld 11/15/15
# (c) Massachusetts Institute of Technology 2015
#
# This work may be reproduced, modified, distributed,
# performed, and displayed for any purpose. Copyright is
# retained and must be preserved. The work is provided
# as is; no warranty is provided, and users accept all
# liability.
#

# from Tkinter import *
import serial
import sys
import time

NUM_BOARDS = 2

def find_framing(byte2):
    while 1:
        # find framing
        byte1 = byte2
        byte2 = ord(ser.read())
        if ((byte1 == 1) & (byte2 == 2)):
            break

def main():
    # idle routine
    for i in range(NUM_BOARDS):
        ser.flush()
        ser.write(str(i))
        # find_framing(0)
        out = ord(ser.read())
        if out == 1:
            print("strum", i)
        # ser.reset_input_buffer()

#  check command line arguments
if (len(sys.argv) != 2):
    print "command line: hello.HC-SR04.py serial_port"
    sys.exit()
port = sys.argv[1]

# open serial port
ser = serial.Serial(port, 9600)
ser.setDTR()

while 1:
    main()