ST NFC reader module

[Preetha Muralidharan]

Posted on June 19, 2018 at 18:13

Looking to use ST NFC reader module for reading the tags and the reader must be able to send an unmodulated signal (carrier only at 13.56MHz). I also need to able to see the demodulated signal at one of the pins on the evaluation module. Is there any module that is available ? I am currently using EVAL-ST95HF but unfortunately not able to see the demodulated signal anywhere on the board. Any input on this is much appreciated.

[Ulysses HERNIOSUS]

Posted on July 02, 2018 at 17:03

Hi Preetha,

All data the ST95 receives is put after chip-internal demodulation and decoding into buffers where it can be read via UART/SPI. The CR95 and ST95 are not meant to be used as pure analog frontends. 

Regards, Ulysses

[Preetha Muralidharan]

Posted on July 02, 2018 at 17:08

Hi 

Ulysses,

Can you suggest a reader module which I could use?

Thanks,

Preetha

[Ulysses HERNIOSUS]

Posted on July 03, 2018 at 08:27

Hi Preetha,

ST25R3911B can do this: It has a so called transparent mode where you can change the role of the SPI pins to output digitized demodulated signal / receive digital modulation signal. Maybe this is what you are looking for. If you can provide some more infos on what you actually would like to achieve I may be able to give you more elaborated information.

Regards, Ulysses

[Preetha Muralidharan]

Posted on July 04, 2018 at 18:01

Hi Ulysses,

Thanks for the suggestion. I am looking to program the module to send just the carrier signal (13.56 MHz) and turn off the modulation. Can I do that using the PC software provided for this module?

Thanks,

Preetha

[Ulysses HERNIOSUS]

Posted on July 05, 2018 at 08:25

Hi Preetha,

yes, of course. It is a mere flip of a bit in the register map or you press one of the various 'Configuration' buttons in the ST25R3911B-DISCO GUI. However control of the Transparent mode to see demodulated pattern is not foreseen in this GUI. Depending on what you actually want to receive an option may also be the so-called observation modes. 

However both options require pre-setting analog params for the expected received patterns for best performance.

Still don't get your big picture.

Regards, Ulysses

[Preetha Muralidharan]

Posted on July 10, 2018 at 15:10

Hi Ulysses,

Thanks for your reply. I am now trying to configure the ST25R3911B to send the carrier by configuring the Operation Control Register to 0x88 (En OSC and en TX)  using the PC software Disco kit. I am able to see a demodulation but not able to find how to transform it to see a pulse drain digitised output. Any leads on this would be helpful.

Thanks,

Preetha

[Ulysses HERNIOSUS · Accepted solution]

Posted on July 10, 2018 at 16:19

Hi Preetha,

As I have already told you: the disco does not have support for the transparent mode. It can send the 0xdc command but that leaves the chip only for a very small moment in that mode until it drives /SS high again. If you want to use that then you have to write your own FW.

Once more: Depending on what you actually want to receive an option may also be the so-called observation modes on CSI/CSO.

If you can provide some more infos on what you actually would like to achieve I may be able to give you more elaborated information.

Regards, Ulysses