How to get a RF baudrate of 424 kbps with the ST25R95 with ISO/IEC 14443 Type A?

[StuN1]

Hello everyone,

A RF baudrate of 424 kbps with ISO/IEC 14443 Type A seems possible in the ST25R95 datasheet (page 15).

I checked the SPI bus and this SPI frame is sent, as expected :

control	command	length	<Protocol>	<Parameters>	...
send	ProtocolSelect	length	ISO/IEC 14443 Type A	Tx and Rx RFdatarate	PP	MM	DD
0x00	0x02	0x05	0x02	0xA0	0x00	0x00	0x00

There's no error code until I try to read if a tag is present :

control	command	length	<Data>	...
send	SendRecv	length
0x00	0x04	0x02	0x52	0x07

wait for ST25R95 nIRQ_OUT ... then

	control
	read	...
master send:	0x02	0x00	...	0x00
ST25R95 response:	0x0E	0x86	...	0x00

There I get 0x86 : "Communication error"

*It works fine when "Tx and Rx RFdatarate" is 0x00 (106 kbps). I tested with SPI speed of 625 kHz, 1.25 MHz and 2.5 MHz (I know it's max 2 MHz for ST2595, but those speeds all works with the 106 kbps RF baudrate)


So, how to get a RF baudrate of 424 kbps with the ST25R95 with ISO/IEC 14443 Type A?

(other questions: What is the data we need to send in the SendRecv? (0x52 and 0x07 means what?) Where can I find explanations to the comments of page 22?)

Thanks!

[Brian TIDAL · Accepted solution]

Hi,

higher bit rates are supported on T4AT tags (i.e. not supported on T2T tags). Which tag do you use (manufacturer and model)?

Moving from the default 106 kbps to higher bit rate can be done after the RATS/ATS exchange when entering in isoDep protocol.

If you plan to use this, I would recommend to use the RFAL NFC stack available on st.com. See ST25 embedded NFC library. You can use the polling example and set the maxBR in discParam to RFAL_BR_424.

Regarding your  additional question, 52h is an ISO14443-3 WUPA command. It is described in the ISO14443-3 document. 07h is the transmission flag meaning that the WUPA is 7 bits frame with no CRC (see table 16 in the ST25R95 Datasheet). According to the ISO14443, the WUPA command has to be sent with the default 106 Kbps bit rate.

Rgds

BT

[StuN1]

Thank you Brian,

I use Type 2 tags, so I guess higher bit rates are not supported. I investigated this issue after trying that example code with discParam RFAL_BR_424 unsuccessfully.

I will take a look at ISO14443-3.

Do you have T4T tags to recommand?

Regards,

[Brian TIDAL]

Hi,

I can only recommend ST tags such as ST25TA02 but this tag supports only 106 Kbps.

Rgds

BT