Motor driver

#!/usr/bin/python
'Motor driver program'

import socket

# Define movement commands, output pins, and states. + = pin on, - = pin off.
cmds = {
    'go_forward': ( 4, -5, -6,  7),
    'go_back':    (-4,  5,  6, -7),
    'turn_left':  (-4,  5, -6,  7),
    'turn_right': ( 4, -5,  6, -7),
    'stop':       (-4, -5, -6, -7),
}

# Import and initialise the PiFace module
import piface.pfio as pf
pf.init()

def setout(val):
    'Motor output function'
    for p in val:
        if p < 0:
            pf.digital_write(-p, 0)
        else:
            pf.digital_write(p, 1)

# Set all relays to off
setout('stop')

# Setup socket parameters
HOST = ''
PORT = 54321

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)

while True:
    conn, addr = s.accept()
    print 'Connected from', addr

    # Continous loop that waits for new data and acts depending
    # on data content on it
    while True:
        data = conn.recv(1024).strip().lower()
        print 'Received:', data if data else '<nothing>'
        if not data: break

        if data in cmds:
            setout(cmds[data])
        else:
            conn.send('unknown command')
            print 'unknown command:', data

    conn.close()