RFID Unit issues

  • Hi,

    I'm using RFID Unid with RFID cards and I experience problems.
    I can read UID, if card is on, read and write blocks however I need to go out and put the card back between each command otherwise it doesn't work.
    For exemple, if I send 2 consecutive isCardOn(), only the first one returns True, the second one and more return False.

    Is there anyone who has experienced the same problem?.


  • M5Stack

    that is so weird. did you have another card for the test? or all card has same situation?

  • Hi,
    Thank you for your reply.
    Yes, I tried with 3 other cards and it's the same.
    I have done more tests and it is very surprising.

    The RFID card is located on the top of the device.
    In an infinite loop, I just continuously check isCardOn () and measure the time between each detection.
    Without moving the card of the device, I measure 11 detections continuously with 1.2 seconds between each detection and nearly 6 seconds between the 11th and 12th then another 11 measurements with 1.2 seconds .....

    If I remove the card and put it on quickly, I can measure times less than 1 second.

  • Hi,

    I found a solution.
    I have to limit the I2C frequency to 100,000kbps otherwise it won't work properly.
    This is strange because a frequency of 400,000 kbps works for all other devices and the MFRC522 should work fine at that frequency.

    If anyone has any idea on this limitation, I am very interested.

    Thank you