NFC-Nrf52 doesn't respond wake-up command if crc check is disabled for rx

[Binh]

I implement a card emulation and the card itself doesn't conform to 14443A-3 crc check. I need to disable crc check on card selected event

NRF_NFCT->RXD.FRAMECONFIG &= ~NFCT_RXD_FRAMECONFIG_CRCMODERX_Msk;

However if I do that, on anticollition procedure, it doesn't respond to wake-up command and causes very strange behaviors on the reader.

If I don't disable crc check it works well.

If I try to re-enable crc check on SLP_REQ on EVENTS_RXFRAMEEND but it doesn't help.

Do you know how to bypass crc check and it still respects to sleep/wakeup command?

Thanks in advance.

[Binh]

seems that if CRC is disable. Hardware doesn't handle sleep request automatically. So it doesn't response to wake up command.

[FormerMember]

After doing NRF_NFCT->RXD.FRAMECONFIG &= ~NFCT_RXD_FRAMECONFIG_CRCMODERX_Msk;, what is the register value of RXD.FRAMECONFIG?

[Binh]

It is just default value with crc bit disabled.

[FormerMember]

The following code snipped from wake_on_nfc with NRF_NFCT->RXD.FRAMECONFIG &= ~NFCT_RXD_FRAMECONFIG_CRCMODERX_Msk; added, works fine when I test it here:

int main(void)
{
    utils_setup();
		NRF_NFCT->RXD.FRAMECONFIG &= ~NFCT_RXD_FRAMECONFIG_CRCMODERX_Msk;
    // Turn on LED to indicate that the device entered System ON mode.
    bsp_board_led_on(BSP_BOARD_LED_0);
		
while (true)
{
    if (m_system_off_mode_on)
    {
        nrf_delay_ms(100);
        // Enter System OFF mode.
        NRF_POWER->SYSTEMOFF = 1;
    }
}
}

Is that what you meant, disable CRC and then wake up the chip?

[Binh]

Thanks for the testing :)

But i meant NFC peripheral wakeup and sleep commands. From the nrf52832 spec

The SLP_REQ is automatically handled by the NFC peripheral. 

if CRC bit is enabled NFC behavior is correct

| Rdr | 50  00  57  cd     |  ok | SLP_REQ |
| Rdr | 52                 |     | WUPA    | wakeup request
| Tag | 04  00             |     |         | This is the correct response for wakeup request

If CRC bit is disabled then

| Rdr | 50  00  57  cd     |  ok | SLP_REQ |
| Rdr | 52                 |     | WUPA    | wakeup request
| Rdr | 26                 |     | REQA    | Tag doesn't respond, timeout and reader send Reqest command
| Tag | 04  00             |     |         | Tag responds correctly