tags - android nfc - mifare classic 1k Increment operation tranceive failed -

i want store integer value , increment or decrement api function.

i have readed card utility , content of block 5:

it seems there not value block.

this code:

    int sector = 5;     this.mclassic.connect();     boolean success = this.mclassic.authenticatesectorwithkeya(sector, mifareclassic.key_default );          if(success){             int firstblock = mclassic.sectortoblock(sector);             log.i("mifare classic", "first block of given sector:" + firstblock);               //set value = 0             byte[] zerovalue = {0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,0,0,};             //save value                              mclassic.writeblock(firstblock, zerovalue);              //increment value , store             this.mclassic.increment(firstblock, 1);             this.mclassic.transfer(firstblock);              // read incremented value converting in integer bytearray             b = readsector(firstblock);             data = b.tobytearray();             value = 0;             (int = 0; < data.length; i++)             {                value = (value << 8) + (data[i] & 0xff);             }             log.i("mifare classic", "after increment " + value);         }         mclassic.close(); 

i have returned tranceive failed @ this.mclassic.increment(firstblock, 1); don't understand doing wrong...who can me? lot.

the mifare 1k data-integrity check on value-block. zerovalue block unfortunately not valid value-block. therefore tag complains , error.

you can find format in mifare datasheets (worth reading!)

however, format of value-block simple:

byte 0..3:   32 bit value in little endian byte 4..7:   copy of byte 0..3, inverted bits (aka. xor 255) byte 8..11:  copy of byte 0..3 byte 12:     index of backup block (can value) byte 13:     copy of byte 12 inverted bits (aka. xor 255) byte 14:     copy of byte 12 byte 15:     copy of byte 13 

if store 32 bit value using format above, code work.