Read magnetic card with raspberry and save to Google spreadsheet

Python code with some comments and link:

#!/usr/bin/python

import sys

import usb.core

import usb.util

import json

import gspread

from oauth2client.client import SignedJwtAssertionCredentials

#It’ necessary discover what are VENDOR_ID and PRODUCT_ID of your card reader device with the command lsusb.

#Device are mainly identified using a pair of hexadecimal numbers, like 0acd:0520 .

VENDOR_ID=0x0acd

PRODUCT_ID=0x0520

DATA_SIZE=337

# keycode mapping

key_pages = [

'', '', '', '',

'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',

'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',

'1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '\n', '^]', '^H',

'^I', ' ', '-', '=', '[', ']', '\\', '>', ';', "'", '`', ',', '.',

'/', 'CapsLock', 'F1', 'F2', 'F3', 'F4', 'F5', 'F6', 'F7', 'F8', 'F9', 'F10', 'F11', 'F12',

'PS', 'SL', 'Pause', 'Ins', 'Home', 'PU', '^D', 'End', 'PD', '->', '<-', '-v', '-^', 'NL',

'KP/', 'KP*', 'KP-', 'KP+', 'KPE', 'KP1', 'KP2', 'KP3', 'KP4', 'KP5', 'KP6', 'KP7', 'KP8',

'KP9', 'KP0', '\\', 'App', 'Pow', 'KP=', 'F13', 'F14' ]

key_pages_shift = [

'', '', '', '',

'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',

'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',

'!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '\n', '^]', '^H',

'^I', ' ', '_', '+', '{', '}', '|', '<', ':', '"', '~', '<', '>',

'?', 'CapsLock', 'F1', 'F2', 'F3', 'F4', 'F5', 'F6', 'F7', 'F8', 'F9', 'F10', 'F11', 'F12',

'PS', 'SL', 'Pause', 'Ins', 'Home', 'PU', '^D', 'End', 'PD', '->', '<-', '-v', '-^', 'NL',

'KP/', 'KP*', 'KP-', 'KP+', 'KPE', 'KP1', 'KP2', 'KP3', 'KP4', 'KP5', 'KP6', 'KP7', 'KP8',

'KP9', 'KP0', '|', 'App', 'Pow', 'KP=', 'F13', 'F14' ]

def map_character(c):

    return key_pages[c]

def chunks(l, n):

    """ Yield successive n-sized chunks from l.

    for i in xrange(0, len(l), n):

        yield l[i:i+n]

#below the class to write the spreadsheet

def addrow(info):

     json_key = json.load(open('filedownloadedingoogle.json')) # http://gspread.readthedocs.org/en/latest/oauth2.html

     scope = ['https://spreadsheets.google.com/feeds']

     credentials = SignedJwtAssertionCredentials(json_key['client_email'], json_key['private_key'].encode(), scope)

     gc = gspread.authorize(credentials)

     # Open a worksheet from spreadsheet with one shot

     wks = gc.open("worksheetname").sheet1

     #wks.update_acell('B2', "it's down there somewhere, let me take another look.")

     # Fetch cells in the column 1

     values_list = wks.col_values(1)

     count = 0

     flag = 1

     while flag == 1 :  # This constructs an infinite loop

        if (values_list[count]=='') : # loop on cell list until find out empty one

                flag = 0

        count = count + 1

     wks.update_cell(count, 1, count) # in the line count and column 1 I put the index

     wks.update_cell(count, 2, info)  # in the line count and column 2 I put the info

          

class MagSwipe:

    def __init__(self):

        # find the MagSwipe reader

        device = usb.core.find(idVendor=VENDOR_ID, idProduct=PRODUCT_ID)

        if device is None:

            sys.exit("Could not find MagTek USB HID Swipe Reader.")

        # make sure the hiddev kernel driver is not active

        if device.is_kernel_driver_active(0):

            try:

                device.detach_kernel_driver(0)

            except usb.core.USBError as e:

                sys.exit("Could not detatch kernel driver: %s" % str(e))

        # set configuration

        try:

            device.set_configuration()

            device.reset()

        except usb.core.USBError as e:

            sys.exit("Could not set configuration: %s" % str(e))

        self._endpoint = device[0][(0,0)][0]

    def wait_for_swipe(self):

        # wait for swipe

        data = []

        swiped = False

        print "Please swipe your card..."

        while 1:

            try:

                data += self._endpoint.read(self._endpoint.wMaxPacketSize)

                if not swiped:

                    print "Reading..."

                swiped = True

            except usb.core.USBError as e:

                if e.args[0] == 110 and swiped:

                    if len(data) < DATA_SIZE:

                        print "Bad swipe, try again. (%d bytes)" % len(data)

                        print "Data: %s" % ''.join(map(chr, data))

                        data = []

                        swiped = False

                        continue

                    else:

                        break   # we got it!

        # convert text

        map_keys = lambda c: key_pages_shift[c[1]] if c[0] is 2 else key_pages[c[1]]

        data = "".join(map(map_keys, [(d[0], d[2]) for d in chunks(data, 8)]))

          

     return data

          

if __name__ == "__main__":

    info = MagSwipe().wait_for_swipe()

    addrow(info)