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Original question:

TRF7970A: Linux support for ISO 14443 Mifare Classic Tags

TRF7970A: Is there is way to modify the scan rate / duty cycle of TRF7970A?

Gnanaguru Ganesan
Prodigy 40 points
Part Number: TRF7970A

Tool/software:

Hi fellas,

We have been trying to reduce the scanning period of TRF7970A, so that it would result in reduced energy consumption, like 80% duty likely, it will be polling for 80% and wil be idle for 20% per second. Also, is there is a way to configure this, so the duty cycle can be variable too, thus aiding us configure it thus achieving our desired consumption level.

  • 0
    TI__Guru**** 182636 points

    Hi,

      I'm not an expert in this subject matter but I think reducing the polling rate should help in energy consumption. Perhaps you can add some delay before turning on the RF. After a polling attempt and if you do not delay any cards, perhaps you can  delay or sleep but bear in mind that extensive delay may impact user's experience. Here is also one app note for Minimizing TRF7964A and TRF7970A Current Use During Power-Down Mode (Rev. A).

    void
    Iso15693FindTag(void)
    {
    Trf797xTurnRfOn();

    Trf797xWriteIsoControl(0x02);

    // The VCD should wait at least 1 ms after it activated the
    // powering field before sending the first request, to
    // ensure that the VICCs are ready to receive it. (ISO15693-3)
    McuDelayMillisecond(6);

    flags = SIXTEEN_SLOTS;
    // flags = ONE_SLOT;

    buf[20] = 0x00;
    Iso15693Anticollision(&buf[20], 0x00); // send Inventory request

    Trf797xTurnRfOff();

    Trf797xResetIrqStatus();
    // clear any IRQs
    }