ST25R3911B Custom board not working

[ACogl]

Hi,

I have made a PCB with ST25R3911B. Regarding the matching network and the antenna, I have design them starting from the X-NUCLEO NFC05A1 evaluation board (the antenna is the same).

The firmware on the microcontroller works, because we have tested it with the X-NUCLEO NFC05A1 mounted over NUCLEO F072RB (the microcontroller is the same STM32F072RB and the pinout is the same).

Unfortunately the custom board is not working properly: the IRQ pin is always high (we are using wake up mode for phase/amplitude). In AN4985 there are images of the RF output signal, that are the same that I am obtaining on the X-NUCLEO NFC05A1. Unfortunately on my custom PCB it seems there is not an RF output signal.

In the attached images you can see the voltage value at pin 11 of ST25R3911B (RFIO2), I have an RF output on the EV board, but on my custom board the voltage level is Always at 5V. The voltage at power supply pin is correct, as well as the crystal oscillation frequency.

There must be an hardware error on my custom PCB, but I am unable to find it. Do you have any suggestion?

Best regards

[Ulysses HERNIOSUS · Accepted solution]

Hi,

yes, please do it step by step:

1. Control all the voltages and GND pins on the ST25R3911B.
2. Control also the actual current flowing into the ST25R3911B and compare it to the DS values.
3. Read register 3Fh and control its read content.
4. Set 'en' bit and probe the crystal / oscillator using your scope.
5. Read interrupt status register. Control content and see IRQ line going down

Regards, Ulysses

[ACogl]

​Hi Ulysses,

thank you for your answer.

It was an error in the code, I forgot to change the pin in the the IRQ handler function.

Now it works properly.

Regards, Alessandro