Android NfcV (ISO 15693) tag

Question

Is it possible to write data to specific blocks in memory on the NfcV (ISO 15693) tag? E.g. write data to block# 5 or any specific block#.

I am new to NFC technologies. I am creating an application to read/write NfcV (ISO 15693) tags. I have successfully create the reading portion but the problem is on writing portion. When I want to write some text data into the tag it start from block# 2 to onward and every time doing the same procedure. I have searched lot but I can't find any solution to write data to specific blocks.

Answer 1

The exact details depend on which ISO 15693 compatible chip is inside the tag. The ISO 15693-3 standard lists different write commands. Support for these are all optional, so your tag may support one or more of these or even use a proprietary command for writing data. I would recommend to look up the datasheet of the chip and/or acquire the ISO standard to find out what the right command is.

Once you know what the right command is, you can simply pass the bytes of the command in a byte array to the NfcV.transceive() method. (Usually the command bytes consist of a flag byte, followed by a write command byte, one or more block bytes and the data bytes to be written.)

Answer 2

Tried the following: Getting the "Tag was lost" Exception:

        nfc.connect();
        byte[] arrByt = new byte[7];
        arrByt[0] = 0x40;
        arrByt[1] = 0x21;
        arrByt[2] = 0x06;
        arrByt[3] = 0x00;
        arrByt[4] = 0x00;
        arrByt[5] = 0x00;
        arrByt[6] = 0x00;           
        byte[] response = nfc.transceive(arrByt);

Answer 3

I guess the android framework does not handle the response from the ISO15693 tags very well. I have been playing with HF-I tags. Few commands work flawlessly and for few other commands the NFC stack throws TAG Lost exception.