RFID Programming - Understanding the Basics

When writing information to an RFID tag, information is written in "Words". A word is 2 bytes. 2 bytes is the equivalent of 16 bit. 4 bits (zeros and ones in binary) make up one character that is written into the EPC. For example, 0001 in binary is equal to 1 and 1111 in binary is equal to F. This being said, we must program a tag memory bank (EPC, User, Reserved, or TID) in multiples of 4 characters (16 bit).

A typical EPC is 96 bit but does not have to be that long. If we cut that EPC in half it becomes 48 bits. 48/4 allows us to program 12 characters into the EPC. This can be done because 48 is divisible by 4. Writing 48 bit would require sending 3 "Words" of data. Each word would look something like this:

Word 1: XXXX XXXX XXXX XXXX
Word 2: XXXX XXXX XXXX XXXX
Word 3: XXXX XXXX XXXX XXXX

Where X represents a binary number (0 or 1). The chart below shows binary representation of each character that can be programmed to an RFID IC.