autoreset

#!/usr/bin/python

import RPi.GPIO as GPIO
import sys, os, re, time, fcntl
import errno

fd = sys.stdin.fileno()
fl = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)

GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(False)
dtr = re.compile('.+TIOCM_DTR.+')
start = time.time()
pin = 4

def reset():
  GPIO.setmode(GPIO.BCM)
  GPIO.setup(pin, GPIO.OUT)
  GPIO.output(pin, GPIO.HIGH)
  time.sleep(0.12)
  GPIO.output(pin, GPIO.LOW)

def process():
  while True:
    try: 
      duration = time.time() - start
      input = sys.stdin.readline().strip()
      if input is None: # == "":
        input = sys.stdin.readline().strip()
      if dtr.match(input):
        reset()
        return
      elif duration > 5000:
        return
    except Exception as e:
      if hasattr(e, 'errno'):
	if e.errno != 11: # Ignore resource unavailable
         raise
      else:
        raise

process()
print "avrdude-original: Using autoreset DTR on GPIO " +str(pin)
GPIO.cleanup()
exit