I've set up a RC522 Card on my pi using This Tutorial and hacked together the Read.py and Write.py scripts into a Clone.py script:

#!usr/bin/env python

import RPi.GPIO as GPIO
from mfrc522 import SimpleMFRC522

reader = SimpleMFRC522()

    print("Scan Card Now")
    id, text = reader.read()
    print("Current ID:")
    print("Place Card for Write, Then Press ENTER")
    print("Write Complete")

Which works just fine when testing on blank cards. However, when I tried to clone an old hotel keycard I get:

Traceback (most recent call last):
  File "clone.py, line 16 in <module>
  File "/usr/local/lib/python3.7/dist-packages/mfrc522/SimpleMFRC522.py", line 60 in write
    id, text_in = self.write_no_block(text)
  File "/usr/local/lib/python3.7/dist-packages/mfrc522/SimpleMFRC522.py", line 78, in write_no_block
    data.extended(bytearray(text.ljust(len(self.BLOCK_ADDRS) * 16).encode('ascii')))
UnicodeEncodeError: 'ascii' codec cant encode characters in position 1-2: ordinal not in range(128)

What can I do to fix this?

  • Hello. This looks to be an error with the SimpleMFC522 library not handling 8-bit data, have you tried raising an issue with the author after checking you have the latest version? github.com/pimylifeup/MFRC522-python/issues Feb 23, 2020 at 20:37
  • @RogerJones I've raised the issue on the website, But I'll see if the github gets more of a response. Thank you.
    – RLahey
    Mar 4, 2020 at 4:34
  • Transport and hotel cards are encrypted and can't be read by this simple software.
    – Milliways
    Nov 8, 2022 at 6:02

1 Answer 1


Ah, your hotel card might contain non ASCII characters, say Unicoded Chinese. So you need to decode the Unicoded Chinese characters each of which is denoted by two bytes. Of course hotel cards usually use other tricks to punish the bad guys trying to clone.

  • Thanks for the reply. That would make sense, but when I run the read script, I just get a 12-character number string and 'xE' and I'm fairly confident that those are covered by unicode....
    – RLahey
    Feb 21, 2020 at 16:26
  • Ah my apologies. I was just making a wild guess, that you were a bad guy, don't know nothing about even ASCII. My second guess is that you are after all a good guy, and that a now 5 star hotel is asking you for help, how to avoid the real bad guys cloning their cards and eating free lunch. Now let me see if me the NFC newbie, can wiki, google, and do some experiments to catch you up. Cheers.
    – tlfong01
    Feb 22, 2020 at 1:38
  • 1
    That's alright, anything you can find would be appreciated.
    – RLahey
    Feb 23, 2020 at 17:23

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