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LBier.1
Visitor II
December 23, 2021
Solved

ST25R39 - problems with reading ISO15693

  • December 23, 2021
  • 2 replies
  • 5061 views

Hello all,

I am developing a small reader with ST25R3912 and I can't use the RFAL library because I want to control it in the final application MCU STM8L. I was inspired by this discussion (https://community.st.com/s/question/0D50X00009XkWIfSAN/register-settings-for-st25r3911b-for-iso-15693) and based on it I wrote a short test program that will try to read the UID from Tag (I only use tag 15693 - inside the ICODE SLIX chip). RF IC using 3.3V power supply and antenna is single sided (components recommended by STM25 Antenna Matching Tools)

My ST25R3912 initialization looks like:

WriteToSPI (0x00,0x8B);                  //IO configuration register 1 - address 0x00

             // single side antenna, use RFO1, RFI1, 64 water level for recieve, 32 water level for transmit, 27.12 MHz Xtal, MCU CLK set 6.78MHz, no MCU CLK if Xtal not running  

WriteToSPI (0x01,80);                      //IO configuration register 2 - address 0x01

             //3.3V supply in range: 2.4 V to 3.6 V, Enable VSP_D regulator, MISO pull down disabled  when SS low, MISO pull down disabled  when SS high, Increase MISO driving disabled, slow ramp at Tx on disabled

WriteToSPI (0x02,0xC8);                  //Operation control register - address 0x02

             // Enables oscilator and regulator (ready mode), Enables Rx operation, Both AM and PM channels enabled, Automatic channel selection, Enable Tx operation, Wake-up mode disable                                                             

WriteDirectCmdToSPI (DCMDAdjustRegulators);  //direct command Adjust Regulators 0xD6

WriteToSPI (0x03,0x70);                  //Mode definition register - address 0x03

             // target: initiator, 1110 means Sub-carrier stream mode, no automatic start response RF collision

WriteToSPI (0x04,0x22);                  //Bit rate definition register - address 0x04

              // 0010 means Tx bit rate fc/32, 0010 means Rx bit rate fc/32

WriteToSPI (0x08,0x30);                  //Stream mode definition register - address 0x08

              // 01 means subcarier frequency fc/32 (424kHz), 10 means sub carrier pulses 4, 000 means time period fc/128                       

WiteToSPI (0x09,0x10);                   //Auxillary definition register - address 0x09

              // recieve without CRC, make CRC check, OOK, Enable external field detector, RFO driver tristate disable, BPSK more tolerant disable

WriteToSPI (0x24,0x2C);                  //AM modulation depth control register - address 0x24

            //AM modulated level is defined by bits mod5 to mod0, 010110 means 14.7% (also tested with 01110000 30%)

WriteDirectCmdToSPI (DCMDAnalogPreset);              // 0xCC

               //direct command Analog preset based on Mode definition register and Bit rate definition register

WriteDirectCmdToSPI (DCMDCalModulationDepth); //direct command RFID calibrate modulation depth 0xD7

When I try read some register it looks that my configuration is inside cerrectly.

I'm not entirely sure which registries need to be configured and which don't. is this configuration correct for the 15693 chip and ICODE SLIX inside the label?

    This topic has been closed for replies.
    Best answer by Ulysses HERNIOSUS

    Hi Lukas,

    please use MRT/NRT from our existing software. NRT needs to be extended when you are doing write(-alike) commands without option flag.

    What you receive seems to be ok - you just need to remove SOF/EOF, then Manchester-decode it and check the CRC.

    B7 : SOF (5 bits: 0x17) + 01->0 + carry over 1

    AA : 01->0, 01->0, 01->0, 01->0 + carry over 1

    AA : 01->0, 01->0, 01->0, 01->0 + carry over 1

    AA : 01->0, 01->0, 01->0, 01->0 + carry over 1

    CA: 01->0, 01->0, 01->0, 10->1 + carry over 1

    4C: 01->0, 10->1, 01->0, 10->1 + carry over 0

    35: 10->1, 10->1 10->1, ....

    giving bits 0000 0000 0000 0000 1010 1111 = bytes 00 00 f5.... The two first zero bytes are flags and DSFID.

    BR, Ulysses

    2 replies

    L
    LBier.1Author
    Visitor II
    December 23, 2021

    After that I coded request

    Flag = 0x26         One slot, AFI not set, Inventory command selected, High datarate        

    CMD = 0x01       Inventory request

    My Inventory request looks like like     SOF  Flag  CMD  AFI   Mask_length   Mask_value  CRC                 EOF

                       0x26 0x01   -     0x00                 -                 0xF6 0x0A

    SOF = 0x21

    EOF = 0x04

    I coded it into format, f.e 0x26

    0x26

    into binary                           00          10          01          10

    change MSB to LSB            10          01          10          00

    code to 1_4                        0x20      0x08      0x20      0x02      where 00~0x02, 01~0x08, 10~0x20, 11~0x80

    I got the complete message:

    21.20.08.20.02.08.02.02.02.02.02.02.02.20.08.80.80.20.20.02.02.04

    and I try to read Tag:

    static uint8_t TXReadUID[22]={0x21, 0x20,0x08,0x20,0x02, 0x08,0x02,0x02,0x02, 0x02,0x02,0x02,0x02, 0x20,0x08,0x80,0x80, 0x20,0x20,0x02,0x02, 0x04};  

    uint8_t message_length = 22;

    WriteDirectCMD (DCMDclearFIFO);                       // direct command clear FIFO

    WriteToFIFO(TXReadUID, message_length);           // write data to FIFO

               

    //WriteDirectCMD (DCMDTransmitNoCRC);            // direct command Transmit without CRC

    WriteDirectCMD (DCMDTransmitWithCRC);           // I have tried both  

           

    wait_ms(200);

    ReadFromFIFO(23);

    But when the tag is in range I got some random data

    20.08.00.00.08.00.02.02.00.02.00.02.00.00.00.00.00.20.02.02.00

    When tag is not in range I got data very similar like request

    Do you have any idea, what I am doing wrong?

    which registers give me more information about where the error is and whether the antenna is properly tuned and working?

    Thank you very much for your help !!

    U
    Ulysses HERNIOSUS
    Technical Moderator
    January 3, 2022

    Hi LBier.1,

    most of what you have done looks plausible but you may miss some steps:

    1. Check that MRT and NRT are set to values ok. for ISO15693.
    2. Make sure to set the TX Length register (according to your sub-bitstream) before issuing the C5 send command.
    3. Inspect the interrupt status registers for: I_txe, I_rxs, I_rxe and I_nre
    4. Only in case you have received I_rxe: Inspect FIFO status registers.

    I only detailed what immediately caught my eye - there may be more...

    In general I can only advise you to not open too many development areas at once: New board with your own new software but rather employ some Divide&Conquer:

    1. Observe the SPI sequences from ST25R3911B-DISCO or X-CUBE-NFC5.
    2. Develop your software on one of our existing boards (X-NUCLEO-NFC05 or ST25R3911B-DISCO)
    3. Crossconnect your MCU to the ST25R3911B on X-NUCLEO-NFC05
    4. Crossconnect your board to a NUCLEO-L4 with X-CUBE-NFC6 or ST25R3911B-DISCO.

    Best Regards, Ulysses

    L
    LBier.1Author
    Visitor II
    January 3, 2022

    Dear Ulysses,

    thank you very much for your feedback.

    I've made some progress since the last post.

    I met point 2,3,4 of your post:

    static uint8_t TXReadUID[22]={0x21,0x20,0x08,0x20,0x02,0x08,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x20,0x08,0x80,0x80,0x20,0x20,0x02,0x02,0x04};  

    uint8_t message_length = 22;

    WriteToFIFO(TXReadUID, message_length);                // write my command to FIFO

    WriteSPIregister(0x1D,0x00);                                           

    WriteSPIregister(0x1E,0xB0);                                    // sending 22 bytes

    //WriteDirectCMD (DCMDTransmitNoCRC);                // direct command Transmit without CRC

    WriteDirectCMD (DCMDTransmitWithCRC);

    and also I am checking the I_txe, I_rxs, I_rxe and I_nre

    When I read the FIFO I have got these answers:

    1. Tag is not in range

      FIFO is empty (read it for checking only)

    2. My Tag1 in range

      I always get the answer: B7.AA.AA.AA.CA.4C.35.2D.35.AB.D2.AC.B4.CA.CC.AA.2B.B3.03

      The answer is the same with direct command Transmit without CRC / Transmith with CRC

      The original UID of this tag is E0.04.01.50.C5.82.E6.F5

    3. My Tag2 in range

      I always get the answer: B7.AA.AA.AA.4A.4B.4B.53.B3.CC.CC.D2.CA.AA.AA.2C.B4.B4.03

      The answer is the same with direct command Transmit without CRC / Transmith with CRC

      The original UID of this tag is E0.16.24.01.19.54.BB.33

    The antenna seems to be tuned in (the first good news after a few long nights) and I'm detecting Tag and I'm reading something :)

    However, the data received does not look like the expected response.

    I think I still have some initialization error and I'm getting some RAW data that roughly matches the UID tag, but hasn't the correct format,right?

    Or do I not know how to correctly interpret this data and convert it to a UID?   

     

    Regarding MRT and NRT I am not sure of right settings for 15693 :( (most things in the datasheet are about ISO14443)

    Best regards Lukas

    U
    Ulysses HERNIOSUSAnswer
    Technical Moderator
    January 3, 2022

    Hi Lukas,

    please use MRT/NRT from our existing software. NRT needs to be extended when you are doing write(-alike) commands without option flag.

    What you receive seems to be ok - you just need to remove SOF/EOF, then Manchester-decode it and check the CRC.

    B7 : SOF (5 bits: 0x17) + 01->0 + carry over 1

    AA : 01->0, 01->0, 01->0, 01->0 + carry over 1

    AA : 01->0, 01->0, 01->0, 01->0 + carry over 1

    AA : 01->0, 01->0, 01->0, 01->0 + carry over 1

    CA: 01->0, 01->0, 01->0, 10->1 + carry over 1

    4C: 01->0, 10->1, 01->0, 10->1 + carry over 0

    35: 10->1, 10->1 10->1, ....

    giving bits 0000 0000 0000 0000 1010 1111 = bytes 00 00 f5.... The two first zero bytes are flags and DSFID.

    BR, Ulysses

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