rfid-rc522 Tag is not read

问题

I am using the instructions of https://pimylifeup.com/raspberry-pi-rfid-rc522/ to learn how to read my rfid-rc522.

I installed all the things needed, and cloned from git all the files. I connected accordingly and double checked the wire.

The code in Write.py is

#!/usr/bin/env python

import RPi.GPIO as GPIO
import SimpleMFRC522

reader = SimpleMFRC522.SimpleMFRC522()

try:
        text = raw_input('New data:')
        print("Now place your tag to write")
        reader.write(text)
        print("Written")
finally:
        GPIO.cleanup()

When I run it- The result stops after "Now place your tag to write" and nothing happens when I place my tag. Any help please? What's wrong here? The module gives red light meaning it is connected. Is it really connected? How do I know? Please help.

Edit: My title and tags were wrong in this question due to already saved data. I edited. :)

回答1:

It can be multiple reasons why your reader is not retrieving any data:

The RFID cards that you are providing to the reader are not supported by the ISO 14443: Mifare Classic, 4K. (Some DesFire, etc...) are the cards you want to try. Source: https://en.wikipedia.org/wiki/ISO/IEC_14443
The MFRC522 is not receiving enough input voltage. Try to increase from 3.3V to 4V. I have tried with 5V months and the reader is still running perfectly, but be cautious. The safe range in NXP is from 2.5V to 3.6V. Source: https://www.nxp.com/docs/en/data-sheet/MFRC522.pdf
The library you are using does not support IRQ (Interruption Request). This means the process of reading UIDs is high CPU consuming and low in performance. Try to use this popular library which supports interruptions: https://github.com/ondryaso/pi-rc522 . You will need to connect another wire from the IRQ pin in the MFRC522 to one GPIO pin in the Raspberry that is free and supports reading/writing operations.
Check if SPI interfaces are enable in Raspbian. Open a terminal and run:

ls -l /dev/spi
Lastly, it could be that your reader is broken. Some chinese versions do not work as they should do. Maybe you should buy another one and try more luck.

I suppose you have connected all cables in the correct way between the MFRC522 and the Raspberry Pi. Check that again.

来源：https://stackoverflow.com/questions/50912880/rfid-rc522-tag-is-not-read

标签

python-3.x

raspberry-pi3

rfid