LED display test

leddisplay.py

import serial
import struct
import time

s = serial.Serial('/dev/tty.KeySerial1', 9600, stopbits=serial.STOPBITS_TWO, timeout=1.)

class Display(object):
    
    def __init__(self, serial, receiver='00'):
        self.s = serial
        self.sender_addr = 'FF'
        self.receiver_addr = receiver

    #def wipe(self):
    #    pass

    def write(self, command='A', settings='AA227F000024000001', text='test'):
        preamble = [0x00, 0x00, 0x00, 0x00, 0x00]
        soh = 0x01
        sender = self.sender_addr
        receiver = self.receiver_addr
        stx = 0x02
        cmd = command
        settings = settings
        data = text
        etx = 0x03
        checksum = self._checksum(chr(stx) + cmd + settings + data + chr(etx))
        eot = 0x04

        #message = struct.pack('%ssB2s2sBs%ss%ssB4sB' % 
        #    (len(preamble), len(data), len(settings)), 
        #    ''.join(map(chr, preamble)), soh, sender, receiver, stx, cmd, settings, data, etx, checksum, eot)
        
        data = '000000'.decode('hex')
        message = struct.pack('%ss' % (len(data)), data)
        s.write(message)
        #time.sleep(0.1)
        #s.write(chr(eot))
        rx = s.read(2)
        print 'from display: ', rx.encode('hex')

    def _checksum(self, data):
        """
        return checksum
        data contains: etx, cmd, data, etx
        """
        print data.encode('hex')
        checksum = hex(sum([ord(c) for c in data])).upper()
        checksum = checksum[2:]
        if len(checksum) == 3:
            checksum = '0' + checksum
        elif len(checksum) == 2:
            checksum = '00' + checksum
        elif len(checksum) == 1:
            checksum = '000' + checksum
        print 'checksum: ', checksum
        return checksum


d = Display(s, receiver='00')
#d.write(command='A', settings='AA427F000023590001', text='hello')
d.write(command='A', settings='AA227F000024000001', text='HELLO')