rpi2-digital-tip-jar.py

# useful imports
from securesubmit.services import HpsServicesConfig
from securesubmit.services.gateway import (
        HpsCreditService,
        HpsTrackData,
        HpsEncryptionData,
        HpsException
        )
from time import sleep

# filename template for controlling the onboard LEDs
filename = '/sys/class/leds/led{0}/brightness'

def change(led, what):
    '''
    changes a given onboard `led` to the `what` brightness level
    
    ## Expected values
    
    `led`
    - `0` - activity LED
    - `1` - power LED
    
    `what`
    - `0` - off
    - `1` - on
    '''
    tf = open(filename.format(led), 'w')
    tf.write(what)
    tf.close()

def blink(led):
    '''
    blinks a given onboard `led` for 2 seconds
    
    ## Expected values
    
    `led`
    - `0` - activity LED
    - `1` - power LED
    '''
    for i in range(10):
        change(led, '1')
        sleep(0.2)
        change(led, '0')
        sleep(0.2)

# start with the LEDs off
change(0, '0')
change(1, '0')

# build our configuration object
config = HpsServicesConfig()
config.secret_api_key = 'skapi_cert_MaePAQBr-1QAqjfckFC8FTbRTT120bVQUlfVOjgCBw'
config.version_number = '0000'
config.developer_id = '000000'

# create a new service object to call Portico
service = HpsCreditService(config)

# loop while waiting for input from card reader
while True:
    # read input from keyboard
    # the card reader sends track data + '\n'
    track_data_string = raw_input("> ")

    # build track data object to be passed to `service`
    track_data = HpsTrackData()
    track_data.value = track_data_string
    track_data.method = 'swipe'
    track_data.encryption_data = HpsEncryptionData()
    track_data.encryption_data.version = '01'

    try:
        # attempt a charge (CreditSale) using the track data obtained from the reader
        response = service.charge(
                1.00,
                'usd',
                track_data
                )
        # log the transaction id
        print response.transaction_id
        # blink the activity LED (green) for success
        blink(0)
    except HpsException, e:
        print "failure"
        # blink the power LED (red) for failure
        blink(1)