control 2-input H-Bridge with control and disable bit (K1=K4=C, K2=K3=not (C or D))

hbridge2.py

#!/usr/bin/python

import RPi.GPIO as GPIO
import sys

GPIO.setmode(GPIO.BOARD)

C = 38 # G20
D = 40 # G21

if len(sys.argv) < 2:
	print "usage: %s [forward|reverse|coast]" % (sys.argv[0],)
	raise SystemExit

GPIO.setwarnings(False)
GPIO.setup([C, D], GPIO.OUT, initial=GPIO.LOW)

if sys.argv[1] == 'forward':
	GPIO.output(C, False)
	GPIO.output(D, False)
elif sys.argv[1] == 'reverse':
	GPIO.output(D, False) # set first
	GPIO.output(C, True)
	#GPIO.output(D, False)
elif sys.argv[1] == 'coast':
	GPIO.output(C, False)
	GPIO.output(D, True)
#elif sys.argv[1] == 'reverse2':
#	GPIO.output(C, True)
#	GPIO.output(D, True)
else:
	print "unrecognized: %s" % (sys,argv[1],)