MSR900 MagStripe reader/writer.

gistfile1.py

import sys, serial
from operator import eq

ser = serial.Serial('/dev/ttyUSB0', 9600)

init = [0x61, 0x65, 0x61]
delimiter = [0x3F, 0x1C, 0x1B]

ok = [0x30]
errors = [0x31, 0x32, 0x34, 0x39]

def send(data):
    ser.write(chr(0x1B))

    if type(data) is int:
        ser.write(chr(data))
    elif type(data) is str:
        ser.write(data)
    elif type(data) is list:
        for c in data:
            send(c)

def erase(tracks):
    tracks &= 0x3
    send('c')
    send(tracks)
    return ser.read(2)[1]

def cardwrite(tracks):
    t1, t2, t3 = tracks
    card_data = [0x1B, 0x01] + t1 + [0x1B, 0x02] + t2 + [0x1B, 0x03] + t3
    data_block = [0x1B, 0x73] + card_data + [0x3F, 0x1C]
    cmd = [0x1B, 0x77] + data_block

    send(cmd)
    print cmd
    return ser.read(2)[1]

def cardread():
    send('r')

    msg = []
    while True:
        next = ord(ser.read(1))
        msg += [next]
        
        if len(msg) >= 4:
            a, b, c = msg[-4:-1]
            if a == delimiter[0] and b == delimiter[1] and c == delimiter[2]:
                break

    return msg

def get_tracks(data):
    buf = []
    track1 = []
    track2 = []
    track3 = []

    for a, b in zip(data, data[1:]):
        buf += [a]
        if a == 0x1B:
            if b == 1:
                buf = []
            if b == 2:
                track1 = buf[1:]
                buf = []
            if b == 3:
                track2 = buf[1:]
                buf = []
        track3 = buf[1:]

    return (track1, track2, track3)

#send(init)

data = cardread()
t1, t2, t3 = get_tracks(data)

print "track 1"
print "".join([chr(c) for c in t1])
print "track 2"
print "".join([chr(c) for c in t2])
print "track 3"
print "".join([chr(c) for c in t3])

#print erase(0x3)

#print cardwrite((list("hello"), list("world"), [1, 2, 3]))