ST25R3911B with VDD powered by 3.3V reports 0V for VDD, VSP_A, VSP_D & VSP_RF

[BNaya.1]

I have ported the STM32F4 firmware written for NFC05A1 board and got it to run well on a Nucleo STM32F0 board.

Since then, I have since designed and prototyped a custom board with with the NFC05A1 reference design copied and controlled with an STM32F0.

The only difference between this board and my Nucleo paired evaluation board set-up is that I have 3.3V going to both VDD and VDD_IO of the ST25R3911B, unlike the reference design which has a VDD of 5V.

My design does not seem to be working properly, even though the SPI interface is working correctly and I can read/write registers.

I have noticed this:

When I run my firmware on the NFC05A1, I can read the correct values for the Power Supplies using the Measure Voltage command, ie:

VDD = 5.1V

VRF = 5.1V

VSA = 3..4V

VSD = 3.4V

BUT, when I run the same firmware on my board (even if I set the sup3_V bit in the IO Config Register 2), I get ZERO for all these 4 supplies.

Am I doing something wrong?

Do I need to change something in the reference firmware for the NFC05A1 to accommodate the VDD value of 3.3V?

Please advise.

Thanks.

Bob N

[Travis Palmer]

​Hello Bob,

The NFC05A1 xtal should be fine with 8.2pF caps. You can easily verify using a scope.

Be aware that the capacitance of the scope probe may change start-up timings of the crystal.

Yes, the murata recommendation is to have them floating. As far as i know, they are floating themslef (inside the Xtal).

On our demo kits those pins are connected to GND and working like a charm. The orientation of the crystal can be a problem sometimes (90° turned).

BR Travis

[BNaya.1 · Accepted solution]

Travis & Ulysses,

I think the guys who manufactured my prototype board populated some other crystal in there (and did not even assemble it properly).

Once I had a skilled technician replace it with the proper Murata crystal, my board is working very nicely 😊

Many thanks to both of you!!

Bob N

[BNaya.1]

My 27.12 MHz crystal was either bad (wrong crystal or badly assembled).

This issue is now CLOSED/ANSWERED thanks to Ulysses and Travis.