Reader TX time?

[Stinde]

I have custom NFC reader board with ST25R3916. The antenna has been geber copied from X-Nucleo-NFC06A1 board and the matching circuit is modified from X-Nucleo board. The varicap values have been merged with fixed capacitors. The MCU is STM32L476 and the FW is slightly modified from en.X-CUBE-NFC6. I have commented out (hopefully) all AAT and antenna tuning related lines on analogConfigTbl_NFC6A1.c

When I measure the X-Nucleo board, TX signal is on about 70ms. On the custom board the on time is 1.2s

What could cause the longer TX on time on the custom board?

Best Regards,

Stinde

[Ulysses HERNIOSUS]

Hi Stinde,

my first idea here would be that the interrupt is not working, RFAL running for every frame into safety timeouts - prolonging all sequences, triggering timeout handling. If that is not the case then my second guess would be too much noise in the system, similarly triggering collision/error handling.

If those two ideas don't help then please use a logic analyzer to look into SPI communication. If you provide them here we can also have a look.

Best Regards, Ulysses

[Stinde]

Hi Ulysses

Here are the IRQ pin signals and TX signals of X-Nucleo board and my board.

BR,

Stinde

[Ulysses HERNIOSUS]

Hi Stinde,

clearly the interrupt is not being handled in this case. Interrupt pulses should be have a length below 100us (Interrupt latency + Issuing Interrupt status read command on SPI). I assume the ISR does not get triggered. Did you change its pin assignment?

Regards, Ulysses