display.py

#!/usr/bin/env python

import subprocess

class MyDisplay:

    def __init__( self ):
        self.value = 0

        self.proc = subprocess.Popen(

            ["./display_ctl"],
            stdout = subprocess.PIPE,
            stdin = subprocess.PIPE
        )

    def __del__(self):
        self.proc.terminate()

    def set_value( self, val ):
        self.value = val
        self.proc.stdin.write( str(val) + '\n')
        print 'Set value', val

    def get_value( self ):
        return self.value



if __name__=="__main__":

    dev = MyDisplay()
    dev.set_value( 15 )