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TRF7960A: Example code for Workarounds?

Ted Huh
Expert 3555 points

Part Number: TRF7960A

Team,

in SLOA155, TRF7960A Firmware Design Hints document, it has some workarounds for wrong ISO14443A tag working.

for paragraph 4 and 5 it says:

-----------------------------------------------------------

4 Wrong Data Due to Overshoots

Description

The ISO14443A 106-kbps decoder gives wrong data in certain condition. When the analog front end filter overshoots, the digitizer might produce a rising edge on the subcarrier data. If this occurs within a small time window, the decoder produces false data. This happens extremely rarely and is dependent on the antenna and filter characteristics.

Workaround

Switch to PM channel or adjust gain to avoid overshoots in the analog filter.

5 ISO14443A Decoder

Description

ISO14443A subcarrier decoded incorrectly – reading holes.

Workaround

Adjust gain setting of main RX channel; repeat reading until correct data results. (This might require additional time.)

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1. Do we have example codes for these workarounds(for 4 PM channel Switching, 5 repeat reading until correct data results)?

2. How to adjust gain to avoid overshoots in the analog filter? do we have guideline for this?

Best Regards,

Ted

  • 0
    TI__Guru*** 135355 points
    Hello Ted,

    We do not have any examples or guidelines for this, and to be honest that hasn't really come up with any customers during all my time working on the TRF7960A. Between using the TI-approved matching network and properly tuning the antenna for 13.56MHz operation, there haven't been cases of the wrong data due to overshoots.

    Looking over what is described, I am thinking that point #4 only applied when using an external power amplifier with the TRF7960A, as at least the overshoot would make in that context compared to the standard operation where that hasn't occurred for customers using the device.

    I don't have any experience with adjusting the gain to address issues with reading holes, typically that occurs due to a mismatch in antenna size between tag and device. If the antennas are well matched in size and read holes still exist in general that would mean the antenna tuning may be at fault.

    What is occurring with the device that prompted investigation into those workarounds?
  • 0 in reply to Ralph Jacobi
    TI__Expert 3555 points

    I will check with customer. because this customer is in MM, I have limited information.

    Ted