CR95HF tag detection

[KlemenPfce]

We developed custom PCB with CR95HF on it. 

PCB on itself was tested and RF circuit tuned(PCB and antenna design is based on development kit), antenna frequency is at 13.56MHz(+/- 0.5KHz), at around -60dB, uart communication working, can put CR95HF to sleep, wakeup, set register and protocols, but the problem is that we can not detect NFC tag (we use 14443A). 

Also we can't successfully finish calibrate process, described in datasheet, since the tag is never detected. We don't have a lot of experience with RF system, so looking for any kind of help.

Commands we use:

-protocol setup 0x0202020000

-tag respond request 0x04022607

Kind regards,

Klemen

[Brian TIDAL]

Hi Klemen,

what are the return codes of the protocolSelect command and of the sendRecv command?

Can you connect a logic analyzer on SSI_0, SSI_1, UART_RX / IRQ_IN, UART_TX / IRQ_OUT and SPI_SS and provide a trace from the power-up up to the protocolSelect and sendRecv commands? 

With an oscilloscope, can you probe the RF field after the protocolSelect command (just connect the gnd of the probe to the tip of the probe and put the probe in the field and you should be able to capture the field)? 

"PCB and antenna design is based on development kit": can you share details: which development kit: X-NUCLEO-NFC03A1 or other kit?

Which tag do you use (manufacturer/model)? Can you check the tag is alive (e.g. use the NFC reader from a  smartphone with STNFCTap app)?

Make sure to follow AN5248 ST25R95 transceiver antenna tuning circuit with EMI filter

Also, I would recommend to base your FW development on top of ST RF abstraction layer (RFAL). See STSW-ST25R017 ST25 embedded NFC library.

Rgds

BT