SLOA246B January   2018  – March 2019 TRF7964A , TRF7970A

 

  1.   Frequently asked questions for TRF7970A and TRF7964A devices
    1.     Trademarks
    2. 1 General Questions
      1. 1.1 What is the TRF79xxA?
      2. 1.2 What protocols are supported by the TRF7960A, TRF7970A, and variants?
      3. 1.3 What evaluation hardware and firmware should I get to evaluate the TRF79xxA devices?
      4. 1.4 What are the expected read ranges for NFC/RFID tags with TRF79xxA evaluation hardware?
      5. 1.5 The TRF7970AEVM is not available anymore, what is the replacement?
    3. 2 NFC/RFID Operating Mode Questions
      1. 2.1 Reader/Writer Mode
        1. 2.1.1 What is the difference between an NFC tag and an HF RFID tag?
        2. 2.1.2 Why is NDEF used? What advantages does NDEF provide?
        3. 2.1.3 How do I read NFC/RFID tags with the TRF79xxA series of devices?
      2. 2.2 Peer-to-Peer (P2P) Mode
        1. 2.2.1 What is NFC peer-to-peer mode?
        2. 2.2.2 How do I send peer-to-peer messages to NFC devices with the TRF79xxA series of devices?
        3. 2.2.3 What is the difference between passive and active P2P?
      3. 2.3 NFC Card Emulation Mode
        1. 2.3.1 What is NFC tag or card emulation?
        2. 2.3.2 How do I emulate an NFC tag or card with the TRF79xxA series of devices?
    4. 3 Hardware and Design Questions
      1. 3.1 Where can I get schematics and layout files for the TRF79xxA devices?
      2. 3.2 How do I design and tune an antenna to 13.56 MHz for the TRF79xxA devices?
      3. 3.3 Does TI provide FCC certification for the TRF79xxA devices?
      4. 3.4 What TI reference designs are available for the TRF79xxA devices?
    5. 4 Software Questions
      1. 4.1 I need to read a non-NFC compliant tag or transponder, what firmware example should I use?
      2. 4.2 Are there any firmware examples available for TI MCUs other than MSP430 and MSP432 MCUs?
      3. 4.3 Is there support for NFCLink with NCI?
      4. 4.4 Are authentication examples available for the TRF79xxA devices?
      5. 4.5 What are the recommended TRF79xxA register settings or device configuration?
      6. 4.6 What does an IRQ status of 0xC0 mean?
      7. 4.7 Are software examples available to read Topaz-512 (NFC Forum Type 1) tags?
      8. 4.8 Are software examples available to read iCLASS or PicoPass tags?
    6. 5 Miscellaneous Questions
      1. 5.1 Is there any support for RF power amplifiers?
      2. 5.2 Is there any TI training collateral for NFC?
      3. 5.3 Are there Energia or Arduino examples for the TRF79xxA?
      4. 5.4 What IDEs are supported for Texas Instruments TRF79xxA firmware examples?
      5. 5.5 What Android handset interoperability is supported?
      6. 5.6 How do I configure the TRF79xxA to output a continuous or unmodulated RF field?
    7. 6 Comparison of TI NFCLink Standalone Firmware and TI RFID Reader Example Firmware
      1. 6.1 NFCLink Standalone Firmware
      2. 6.2 RFID Reader Example Firmware
      3. 6.3 Memory Footprint Comparison
    8. 7 References
  2.   Revision History

4.6 What does an IRQ status of 0xC0 mean?

An IRQ status of 0xC0 indicates that both the TX complete and RX start bits have been set. This can be an issue as the TRF79xxA FIFO is supposed to be reset with the direct command 0x0F after a TX operation is finished and before an RX operation begins. Not resetting the FIFO can result in corrupted RX data.

The typical cause for this issue is that the interrupt for the TX complete event (IRQ status = 0x80) is not serviced quickly enough. This can either be an issue with priority of the interrupt or MCU clock speed. Ensure that the IRQ interrupt is serviced correctly and that the FIFO is reset with the direct command 0x0F after receiving the TX complete event. When done correctly, then the interrupt for either the RX complete event (IRQ status = 0x40) or the RX in progress event (IRQ status = 0x60) should be correctly received.