Write Lock Block command for NfcV

Question

I am trying to lock data to a NXP ICODE SLIX SL2S2002 tag type 5 (ISO 15693) to make it readonly by using the WRITE SINGLE BLOCKS command through the NfcV object in an ionic based app:

    private readonly cmdISO15693 = {
    READ_SINGLE_BLOCK: 0x20,
    WRITE_SINGLE_BLOCK: 0x21,
    LOCK_BLOCK: 0x22
};

this.nfc.connect('android.nfc.tech.NfcV', 500)
      .then(
        (data) => {
            console.log('connected to', this.nfc.bytesToHexString(tag.id.reverse()).toUpperCase());
            console.log('maxTransceiveLength: ', data);

            const offset = 0; // offset of first block to read
            const blocks = 8; // number of blocks to read
            const bytesOfText: number[] = this.nfc.stringToBytes(text);
            console.log('bytesOfText: ', bytesOfText);
            console.log('hex string: ', this.nfc.bytesToHexString(bytesOfText));

            let cmd = new Int8Array([
                0x60, // 0: flags: addressed (= UID field present) or 0x90 0x60 0x40 0x20??
                this.cmdISO15693.READ_SINGLE_BLOCK, // 1: command
                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // 2-9 placeholder for tag UID
                0x00  // 10: block number
                // 0x00, 0x00, 0x00, 0x00  // 11- DATA
                // ((blocks - 1) & 0x0ff)  // number of blocks (-1 as 0x00 means one block)
            ]);
            console.log('cmd: ', [...cmd]);

            // tag uid in which direction
            cmd = arrayCopy(tag.id.reverse(), 0, cmd, 2, 8);
            console.log('cmd new: ', [...cmd]);
            console.log('cmd buffer: ', cmd.buffer);
            // arrayCopy(bytesOfText, 0, cmd, 11, 4);

            this.nfc.transceive(cmd.buffer)
              .then((res: ArrayBuffer) => {
                  console.log('transceive result:', res);
                  try {
                      console.log(Utf8ArrayToStr(res));
                  } catch (e) {
                      console.log('Utf8ArrayToStr not possible', e);
                  }

                  this.nfc.close().then(() => console.log('closed connection'))
                    .catch((err) => console.log('error closing', err));
              })
              .catch((err) => {
                  console.log('error while transceive', err);
                  this.displayToast('Error to write the RFID-Chips.', 'warning');
              });

I don't know which bytes I have to pass for each block. I use the phoneGap-NFC plugin for ionic. Every time I try to set it readonly I get the answer 'Tag was lost' and by the READ_SINGLE_BLOCK command, too. The Ionic method makeReadOnly() does not work because this is blocked by the tag. I have to set it by means of the bytes. I dont know do I have to use Int8Array or Unit8Array, do I have to use reverse() on the tagId because the hex is mirrored or do I just pass the UID bytestring instead of the hexstring?

Daniel Daniel · Accepted Answer · 2021-01-26T10:55:24

     this.nfc.connect('android.nfc.tech.NfcV', 500)
      .then(
        async () => {
          const blocks = 28; // 28 read by app TagInfo memory size: 28 blocks with 4 bytes per block
          const cmdLock = this.cmdISO15693.OPTION_FLAG  // 0 flag addressed
            + ' ' + this.cmdISO15693.LOCK_BLOCK        // 1 command
            + ' ' + this.tagIdHexArr.join(' ');         // 2-9 tag uid

          let blockError = false;
          let resTransceive: ArrayBuffer;
          for (let i = 0; i < blocks; i++) {
            const block = this.nfc.bytesToHexString([i]).toUpperCase();
            const cmd = cmdLock + ' ' + block;

            try {
              resTransceive = await this.nfc.transceive(cmd);
              try {
                const view = new Uint8Array(resTransceive);
                const resHex = this.nfc.bytesToHexString([...view]);
                console.log(resHex);
              } catch (e) {
                console.log(e);
              }
            } catch (e) {
              blockError = true;
              return;
            }
            if (blockError) {
              return;
            }
          }
          if (blockError) {
            this.notification.push(new Notification(NotificationType.ERROR, 'Fehler beim Setzen des Schreibschutzes.'));
          }
          this.nfc.close().then(() => console.log('Closed connection'))
            .catch((err) => console.log('Error closing: ', err));
        });

Fixed the problem!

Write Lock Block command for NfcV

1 Answers