I trying comunication with a tag ISO14443B. I would like to see also the CRC, but I can't receive it, b7 in register 0x01 is 0.
This is my configuration:
Register 0x09 => 0x31
Register 0x01 => 0x0C 00001100 so b7 is 0
Page 59 of datasheet
B7 rx_crc_n CRC Receive selection
0 = RX CRC (CRC is present in the response) 1 = no RX CRC (CRC is not present in the response)
Register 0x00 => 0x21
Trasmission with CRC send 2 byte 0x06 and 0x00. It's a tag ST512
WriteSPI(0x8F);WriteSPI(0x91);WriteSPI(0x3D);WriteSPI(0x00);WriteSPI(0x20);WriteSPI(0x06);WriteSPI(0x00);
WriteSPI(0x5C); // Read register 0x1C FIFO Statusi = ReadSpi();i is always 1, the byte of selection.
Where is CRC?
Thank you for help
Hello John,
the CRC is automatically removed by the TRF. You can check if the CRC was OK by checking if there was a irq_err1 (CRC, or proto in case of NFC).
If you want to actually see the CRC, then you will have to set b7 in register 0x01 to 1 (CRC is not present in the response).
The CRC can be read out of FIFO then, if the NFC Target (or RFID Tag) appended a CRC. In your case there should be Expected Response Bytes + CRC1 + CRC2 in FIFO then.
That's the way how I checked the correct calculation of CRC by TRF, and it worked for me (NFC active-active).
Hope this helps.
Regards Marco
I have to correct myself:
This worked for me in NFC 106k mode. I also tried it with NFC 212 and NFC 424. In both cases the CRC is always attached independend from the TX method, and RX without CRC delivers only the payload in both cases (424 and 212).
I do not know if this helps you for your ISO14443B problem, but I will keep in with this issue, as I am currently analysing the physical layer behaviour of TRF in parallel with the NFC standard.
John -
You would also please notice that you do not see the SOF or EOF in the response either. This is because the TRF79xx devices check and remove these portions of information to ease your firmware development. (likewise you are not needing to send CRC either for ISO compliant devices)
attached is a .c file which contains support for the ST tags.
Initiate, Select, and GetUID
6330.14443_w_ST_TAG_Support.zip
BR-
Josh
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john -
no - we don't have anything like this since i have not heard any need for it - maybe someone else has and can contribute this/that here -
Ok thank you Josh. I try to develop to my self. I have source of Stellaris for Mifare DM0, so I hope is useful.