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#! /usr/bin/python
# -*- encoding: utf-8 -*-
from serial import Serial
import curses.ascii
import time
import pycountry
DEVICE = '/dev/ttyACM0'
DEVICE_RATE = 9600
PAYMENT_MODE = 'card' # 'card' or 'check'
CURRENCY_ISO = 'EUR'
AMOUNT = 12.42
def serial_write(serial, text):
assert isinstance(text, str), 'text must be a string'
serial.write(text)
def initialize_msg(serial):
max_attempt = 3
attempt_nr = 0
while attempt_nr < max_attempt:
attempt_nr += 1
send_one_byte_signal(serial, 'ENQ')
if get_one_byte_answer(serial, 'ACK'):
return True
else:
print("Terminal : SAME PLAYER TRY AGAIN")
send_one_byte_signal(serial, 'EOT')
# Wait 1 sec between each attempt
time.sleep(1)
return False
def send_one_byte_signal(serial, signal):
ascii_names = curses.ascii.controlnames
assert signal in ascii_names, 'Wrong signal'
char = ascii_names.index(signal)
serial_write(serial, chr(char))
print('Signal %s sent to terminal' % signal)
def get_one_byte_answer(serial, expected_signal):
ascii_names = curses.ascii.controlnames
one_byte_read = serial.read(1)
expected_char = ascii_names.index(expected_signal)
if one_byte_read == chr(expected_char):
print("%s received from terminal" % expected_signal)
return True
else:
return False
def prepare_data_to_send():
if PAYMENT_MODE == 'check':
payment_mode = 'C'
elif PAYMENT_MODE == 'card':
payment_mode = '1'
else:
print("The payment mode '%s' is not supported" % PAYMENT_MODE)
return False
cur_iso_letter = CURRENCY_ISO.upper()
try:
cur = pycountry.currencies.get(alpha_3=cur_iso_letter)
cur_numeric = str(cur.numeric)
except:
print("Currency %s is not recognized" % cur_iso_letter)
return False
data = {
'pos_number': str(1).zfill(2),
'answer_flag': '0',
'transaction_type': '0',
'payment_mode': payment_mode,
'currency_numeric': cur_numeric.zfill(3),
'private': ' ' * 10,
'delay': 'A011',
'auto': 'B010',
'amount_msg': ('%.0f' % (AMOUNT * 100)).zfill(8),
}
return data
def generate_lrc(real_msg_with_etx):
lrc = 0
for char in real_msg_with_etx:
lrc ^= ord(char)
return lrc
def send_message(serial, data):
'''We use protocol E+'''
ascii_names = curses.ascii.controlnames
real_msg = (
data['pos_number'] +
data['amount_msg'] +
data['answer_flag'] +
data['payment_mode'] +
data['transaction_type'] +
data['currency_numeric'] +
data['private'] +
data['delay'] +
data['auto'])
print('Real message to send = %s' % real_msg)
assert len(real_msg) == 34, 'Wrong length for protocol E+'
real_msg_with_etx = real_msg + chr(ascii_names.index('ETX'))
lrc = generate_lrc(real_msg_with_etx)
message = chr(ascii_names.index('STX')) + real_msg_with_etx + chr(lrc)
serial_write(serial, message)
print('Message sent to terminal')
def compare_data_vs_answer(data, answer_data):
for field in [
'pos_number', 'amount_msg',
'currency_numeric', 'private']:
if data[field] != answer_data[field]:
print(
"Field %s has value '%s' in data and value '%s' in answer"
% (field, data[field], answer_data[field]))
def parse_terminal_answer(real_msg, data):
answer_data = {
'pos_number': real_msg[0:2],
'transaction_result': real_msg[2],
'amount_msg': real_msg[3:11],
'payment_mode': real_msg[11],
'currency_numeric': real_msg[12:15],
'private': real_msg[15:26],
}
print('answer_data = %s' % answer_data)
compare_data_vs_answer(data, answer_data)
return answer_data
def get_answer_from_terminal(serial, data):
ascii_names = curses.ascii.controlnames
full_msg_size = 1+2+1+8+1+3+10+1+1
msg = serial.read(size=full_msg_size)
print('%d bytes read from terminal' % full_msg_size)
assert len(msg) == full_msg_size, 'Answer has a wrong size'
if msg[0] != chr(ascii_names.index('STX')):
print('The first byte of the answer from terminal should be STX')
if msg[-2] != chr(ascii_names.index('ETX')):
print('The byte before final of the answer '
'from terminal should be ETX')
lrc = msg[-1]
computed_lrc = chr(generate_lrc(msg[1:-1]))
if computed_lrc != lrc:
print('The LRC of the answer from terminal is wrong')
real_msg = msg[1:-2]
print('Real answer received = %s' % real_msg)
return parse_terminal_answer(real_msg, data)
def transaction_start():
'''This function sends the data to the serial/usb port.
'''
serial = False
try:
print(
'Opening serial port %s for payment terminal with '
'baudrate %d' % (DEVICE, DEVICE_RATE))
# IMPORTANT : don't modify timeout=3 seconds
# This parameter is very important ; the Telium spec say
# that we have to wait to up 3 seconds to get LRC
serial = Serial(
DEVICE, DEVICE_RATE, timeout=3)
print('serial.is_open = %s' % serial.isOpen())
if initialize_msg(serial):
data = prepare_data_to_send()
if not data:
return
send_message(serial, data)
if get_one_byte_answer(serial, 'ACK'):
send_one_byte_signal(serial, 'EOT')
print("Now expecting answer from Terminal")
if get_one_byte_answer(serial, 'ENQ'):
send_one_byte_signal(serial, 'ACK')
get_answer_from_terminal(serial, data)
send_one_byte_signal(serial, 'ACK')
if get_one_byte_answer(serial, 'EOT'):
print("Answer received from Terminal")
except Exception as e:
print('Exception in serial connection: %s' % str(e))
finally:
if serial:
print('Closing serial port for payment terminal')
serial.close()
if __name__ == '__main__':
transaction_start()