problem with NFC handling

[HadarMiz]

Hi,

I'm using the nRF52832 with SDK version 17.0.1.

I've noticed that when the device wakes up from NFC and remains in proximity to the NFC field, it sometimes experiences a watchdog reset.

Could you help identify what might be causing this issue?
Is it possible that we're not handling the NFC interrupt correctly?

Thanks.

[HadarMiz]

Hi Vidar,

We’ve observed a watchdog reset (WD) occurring when the device lands on the NFC pad. Here's the sequence:

• The NFC wakes the device from ULP.

• The NFC pad sends interrupts to the device.

• In rare cases (approximately 1 in 10,000 devices), a watchdog reset occurs.

Our suspicion is that we may not be handling the NFC interrupts properly, which could occasionally cause the device to get stuck.

Regarding your other question, yes we're using your driver implementation.

Thanks,

[Vidar Berg]

Is ULP = System OFF mode? In that case, does your code reload the watchdog just before entering System OFF mode to ensure the timeout is consistent upon wakeup?

[HadarMiz]

I don't believe this issue is related to ULP. The device wakes up and begins receiving interrupts from the NFC as expected.

However, it's possible that a fault in the NFC-related interrupt handling could cause the device to become unresponsive.

[Vidar Berg]

Again, what does ULP (Ultra Low Power) refer to in this context? Is the device woken up from System OFF or System ON mode?

[HadarMiz]

system off

[Vidar Berg]

Thanks for confirming that we are talking about wakeup from System OFF mode. The WDT configuration and counter value are retained through this reset, so the question still remains if there is a possibility that device can wake up with a timeout that is too short.

Ref. Reset behaviour