UHF RFID Tag Partition Instructions and Tag Locking

The UHF tag is actually a small storage space. The RFID Reader only reads the data in the tag through special commands, so the length of data that can be read and written is determined by the RFID electronic tag itself. For details, you can ask the RFID tag supplier .

Note: All the following read and write operations are performed in hexadecimal format, and the data length must be in word (word) as the unit (2byte, that is, 4 bits, such as 0001).

1. Partition

Which areas are the tag memory divided into?

Reserved (reserved), EPC (electronic product code), TID (tag identification number) and User (user) four independent storage blocks (Bank)

RESERVER area: 8byte (4 words) in size, the first 4byte (2 words) is the destruction password (used to destroy the label, generally not used), the last 4byte (2 words) is the access password (used to write data and lock operations) , the default value is: 0000 0000 (destruction password) 0000 0000 (access password).

TID area: 12byte (6 characters), "only readable, not writable", has been written in the factory, it is the unique identifier of the tag, the product identification number of the electronic tag, and the TID number of each manufacturer will be different.

EPC area: It is the electronic product code for identifying the label object. Compared with TID, the difference between EPC and TID is that EPC can be manually written and modified by the user. The data structure of the EPC area is that the first word is the check digit, the second word is the length control, and the last word is the data storage location. When making an inventory, the EPC is displayed according to the length indicated by the length control bit. When actually writing EPC data, the start address is filled with 1, that is, the data is written from the length control bit, and the parity bit will be automatically calculated without manual writing. Length control bit calculation: EPC data length * 2 = i; Convert i to hexadecimal representation, then add 00 after the converted result, and finally get the length control bit data. For example: 0001, i = 4 * 2 = 8 —> 08 —> 0800, the length control bit is 0800, calculated in the program:

Fill in the length according to the actual data length to be written, for example: 0001, the length is 1 word, 4 bits (it should be noted that the data bit length must be a multiple of 4), add the length control bit 0800, and fill in 2 for the length in the software; Example: 0001 Start address: 1. Length: 2. Data: 08000001.

USER area: The length of this memory is determined by the manufacturer of each electronic label, and user-defined data (in hexadecimal form) can be written in the USER area.

2. Tab lock

There are four types of tag lock states, which are described in two cases:

1. If the access password is not modified, it will be the default 00000000:

Unlocked: readable and writable with password 00000000;

Temporary lock: use the password 00000000 to read and write;

Permanent lock: use the password 00000000 to read and not write;

Unlock: Unlock temporarily locked areas and turn them into unlocked states; permanently locked areas cannot be unlocked.

2. If the access password is modified, instead of the default 00000000, it is assumed to be modified to 000000FF:

Unlocked: readable and writable with password 00000000 or 000000FF;

Temporary lock: After the RESERVER area is temporarily locked, use the password 000000FF to read and write; other areas (except TID); after temporarily locking, use the password 00000000 or 000000FF to read and use the password 000000FF to write; other areas (except TID) are permanent After locking, the password 00000000 or 000000FF cannot be read or written;

Unlock: Unlock temporarily locked areas and turn them into unlocked states; permanently locked areas cannot be unlocked.

Note: If you want to lock an area other than the password area, you need to lock two password areas before locking other areas.

Attention should be paid to the EPC area:

In the EPC area, the 0th word is the CRC checksum of the EPC, and the 1st word is the PC value (the length of the EPC). Therefore, starting from the 2nd word is the content of the highest word of the real EPC. Except for special purposes, generally do not select word 0 and word 1 to start output.

[Note] PC+EPC is also called UII

The first 5 bits of the PC high byte represent the word length of the following EPC

Binary hexadecimal corresponds to the length of the EPC

11111 000 F8 00 31

11110 000 F0 00 30

11101 000 E8 00 29

11100 000 E0 00 28

11011 000 D8 00 27

11010 000 D0 00 26

11001 000 C8 00 25

11000 000 C0 00 24

10111 000 B8 00 23

10110 000 B0 00 22

10101 000 A8 00 21

10100 000 A0 00 20

10011 000 98 00 19

10010 000 90 00 18 Word = 288 bits

10001 000 88 00 17

10000 000 80 00 16

01111 000 78 00 15

01110 000 70 00 14

01101 000 68 00 13

01100 000 60 00 12

01011 000 58 00 11

01010 000 50 00 10

01001 000 48 00 9 word 48 00～4F 00

01000 000 40 00 8 word 40 00～47 00

00111 000 38 00 7 word 38 00～3F 00

00110 000 30 00 6 word 30 00～37 00

00110 100 34 00

00101 000 28 00 5 word 28 00～29 00

00100 000 20 00 4 word 20 00～27 00

00011 000 18 00 3 word 18 00～19 00

00010 000 10 00 2 word 10 00～17 00

00001 000 08 00 1 word 08 00～0F 00