mynfcpy.py

import nfc
import struct
import sys
import ndef
# NDEF hex dump
#record = ndef.TextRecord("Hallo Welt", "de")
#print(b''.join(ndef.message_encoder([record])).hex())

def HEX(s):
    return bytearray.fromhex(s)

# test data taken from https://github.com/nfcpy/nfcpy/blob/master/tests/test_tag_tt3.py
ndef_data_3 = HEX(
    "10 01 01 00  05 00 00 00  00 00 01 00  00 10 00 28"
    "d1 02 0b 53  70 d1 01 07  55 03 61 62  2e 63 6f 6d"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "06 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
    "0a 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00"
)

#default NDEF record
record = ndef.TextRecord("Hallo Welt", "de")
ndef_data_area = bytearray(64 * 16)

if len(sys.argv) > 1:
    #command line arg => 'en' text record
    record = ndef.TextRecord(sys.argv[1], "en")

def set_ndef_data(record=ndef.TextRecord("Hallo Welt", "de")):
    global ndef_data_area
    print("set_ndef_data")
    ndef_data_area[0] = 0x10  # NDEF mapping version '1.0'
    ndef_data_area[1] = 3    # Number of blocks that may be read at once
    ndef_data_area[2] = 3     # Number of blocks that may be written at once
    ndef_data_area[4] = 3    # Number of blocks available for NDEF data
    ndef_data_area[10] = 1    # NDEF read and write operations are allowed
    ndef_data_area[13] = 0    # length?
    ndef_data_area[14:16] = struct.pack('>H', sum(ndef_data_area[0:14]))  # Checksum

    #ndef_data_area = ndef_data_3
    #ndef text 
    blob = b''.join(ndef.message_encoder([record]))
    ndef_data_area[16:16+len(blob)] = blob

    ndef_data_area[13] = len(blob)    # length?
    ndef_data_area[14:16] = struct.pack('>H', sum(ndef_data_area[0:14]))  # Checksum

set_ndef_data(record)
#print(b' '.join(ndef_data_area).hex())

def ndef_read(block_number, rb, re):
    print("ndef_read: ", block_number, rb, re)
    if block_number < len(ndef_data_area) / 16:
        first, last = block_number*16, (block_number+1)*16
        block_data = ndef_data_area[first:last]
        return block_data

def ndef_write(block_number, block_data, wb, we):
    print("ndef_write")
    global ndef_data_area
    if block_number < len(ndef_data_area) / 16:
        first, last = block_number*16, (block_number+1)*16
        ndef_data_area[first:last] = block_data
        return True

def on_startup(target):
    print("on_startup")
    idm, pmm, sys = '03FEFFE011223344', '01E0000000FFFF00', '12FC'
    target.sensf_res = bytearray.fromhex('01' + idm + pmm + sys)
    target.brty = "212F"
    return target

def on_connect(tag):
    print("tag activated")
    tag.add_service(0x0009, ndef_read, ndef_write)
    tag.add_service(0x000B, ndef_read, lambda: False)
    return True

def emulate():
    with nfc.ContactlessFrontend('usb') as clf:
        print("with clf")
        #with nfc.ContactlessFrontend('tty:USB0:pn532') as clf:
        #print("while")
        while clf.connect(card={'on-startup': on_startup, 'on-connect': on_connect}):
            print("tag released")
            return

import PySimpleGUI as sg
layout = [  [sg.Text('Text Record'), sg.InputText()],
            [sg.Button('Ok'), sg.Button('Cancel')] ]

# Create the Window
window = sg.Window('NDEF Text Message Emulation', layout) #,return_keyboard_events=True
# Event Loop to process "events" and get the "values" of the inputs
while True:
    event, values = window.read()
    #print("events,values")
    if event in (None, 'Cancel'):	# if user closes window or clicks cancel
        break
    print('You entered ', values[0])
    set_ndef_data(ndef.TextRecord(values[0], "de"))
    emulate()
window.close()