ST25R3916 deactivated by itself after a minute or two

[JLee.47]

Hello,

I incorporated the demo_polling.c example from the RFAL library (STM32CubeExpansion_NFC6_V1.1.0) into my custom application.

My work uses NFC-V tags and by calling demoCycle() function, the application is able to detect the tag repeatedly. 

This is the state machine of my app:

1) Sensor from custom board detects the presence of an object inserted (contains NFC-V tag).

2) App calls demoCycle() repeatedly for a period of 5 seconds, and also services the interrupt from ST25R3916.

3) App successfully detects the NFC-V tag (ID and read data block) over and over again.

4) App stops calling demoCycle() after 5 seconds.

However, I notice if there is no tag activity for about 1 to 2 minutes, the application will stop detecting the tags forever. At this point, when I place a tag nearby, the state is always at RFAL_NFC_STATE_POLL_TECHDETECT. The only way to fix the tag detection is to power cycle the whole board.

It appears the ST25R3916 chip is stuck in some mode (maybe sleep or undefined mode). I am not using LISTEN MODE or WAKEUP mode.

Does the demoCycle() function need to run forever? I also notice each time demoCycle() is called, it generates an interrupt to the app (regardless if a tag is nearby or not).

Please advice, thank you.

[Ulysses HERNIOSUS]

Hi JLee.47,

depending on MCU timer expiration demoCycle() will move to polling and thus enable the field. The direct command for doing this will generate interrupts (signaling success or fail). I think you should analyze the code or SPI traffic what happens in this case.

Maybe you stayed with field-on for 1-2 minutes and your design has a heat issue? But this is currently only a wild guess. Better to do this based on debugging/SPI traffic.

Best Regards, Ulysses

[JLee.47 · Accepted solution]

Thank you Ulysses. Turns out to be a timer bug with my code.