An old script (better here than in Dropbox, dunno what it does).

readclip.py

#!python

import RPi.GPIO as GPIO
import time
import sys

GPIO.setmode(GPIO.BOARD)

bint = 3

bits_channel = [5, 7, 11, 13]

GPIO.setup(bint, GPIO.IN)
map(lambda x: GPIO.setup(x, GPIO.IN), bits_channel)

toeprev = False
number = ""
last_code_time = 0
number_dispatched = True
number_ready = False

while True:
    toe = GPIO.input(bint)
    if (toe != toeprev):
        
        if toe:
            sys.stdout.write('X')
            sys.stdout.flush()
            digit_n = eval('0b'+reduce(lambda x, y: x + y, map (str, map (GPIO.input, bits_channel))))

            if ((digit_n > 9) and (digit_n < 16)):
                digit = ['0','*','#','A','B','C','D'][(digit_n - 10)]
            else:
                digit = str(digit_n)

            if ((time.time () - last_code_time) > 2):
                number_dispatched = False
                number = digit
            else:
                number = number + digit

            last_code_time = time.time()
        else:
            sys.stdout.write('.')
            sys.stdout.flush()

        toeprev = toe
    if (not number_dispatched) and ((time.time() - last_code_time) > 2):
        print "Number > ", number
        number_dispatched = True