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TRF7970A: Issue with Card Emulation mode when receiving first anti-collision SELECT command

Ivan Vlaykov
Prodigy 10 points
Part Number: TRF7970A


Dear Sir or Madam,

I am trying to use the TI TRF7970a chip in card emulation mode (emulating Type 4A tag) together with the STM32L05 MCU. For this purpose I have ported the NFCLink library provided by TI to the MCU I am currently using (changed the SPI drivers, timers, and few other minor things). For the PCD I use the NFC Tools app on Iphone 8 with IOS 14.5 and Nokia 6 with Android 8.1.0.

I do get the REQA command from the PCD (in the NFC_waitForCommand function) and send back the ATQA response to the PCD (in the NFC_Target_StateMachine function). However, the major problem I am facing is that after I send back the response and I go to the NFC_PARAMETER_SELECTION state, and I call the NFC_waitForCommand function to wait for the Select cascade 1 command it seems that I don't get any response back as a result.

If I save all the outputs from the TRF79x0_irqHandler function I get something which I wouldn't expect. Below I attach how I save the outputs from the interrupt handler.

The actual outputs are as following:

I would expect that after the RX_COMPLETE I would have only one TX_COMPLETE as transmit the ATQA response only once.

If you need any additional info please let me know.

Any help will be greatly appreciated as I am stuck at this for quite some time now, and I have no idea how I can proceed.

Kind regards,

Ivan Vlaykov

  • 0
    Prodigy 10 points

    One thing I forgot to mention is that I have managed to use the TRF7970A in a reader/writer mode (although with a different code, not the NFCLink API) to read and write to Type 2A tags.

  • 0 in reply to Ivan Vlaykov
    TI__Mastermind 18265 points

    Hello Ivan,

    you are using a non TI-MCU for controlling the TRF7970A. In this case I do not have the ability to support debug but can confirm that I would not expect multiple TX completes and I cannot say why that is occurring.

    Sorry for not having a better answer for you.

    Best Regards,

    Helfried

  • 0 in reply to Helfried Vollbrecht
    Prodigy 10 points

    Hello Helfried,

    Thank you for your answer.

    I did manage to make some progress with the card emulation. Now after I get the REQA command I manage to send the ATQA response, and do get the Select cascade 1 command. I respond to the select cascade command with my UID; however, then the Iphone stops replying me. Have you heard of a similar issue before, and do you have an idea why this might be happening? (My question is independent of the controller I am using.)

    Thank you in advance!

    Kind regards,

    Ivan

  • 0 in reply to Ivan Vlaykov
    TI__Mastermind 18265 points

    Hello Ivan,

    I have not heard of an issue with the iPhone so far. Because I have no iPhone available I have no personal experience with it. Do you have our NFC demo (DLP7970ABP + EXP430F5529 + NFC GUI) available as reference to check if it will work with your iPhone?

    Best Regards,

    Helfried