Types of Memory for UHF RFID Tags
RFID (Radio-Frequency Identification) tags operating in Ultra-high Frequency (UHF) band and following EPC Global Class 1 Gen 2 regulations use four different types of memory.
- EPC (Electronic Product Code) Memory
- Reserved Memory
- TID (Tag Identifier) Memory
- User Memory
EPC Global Class 1 Gen 2 UHF passive RFID tag is comprised of an antenna, chip, and integrated circuit (ICs). The segmentation of memory in the ICs of EPC Gen 2 UHF RFID tags can be performed in four different methods according to user’s requirement and application demand.
What is the Electronic Product Code Memory?
Applications that require a capacity of at least 96 bits use EPC memory. EPC memory is a writeable memory to store an EPC code having a minimum potential of 96 bits, but more bits can be segmented into ICs as most of them may provide 128 bits and 496 bits. The advantage of EPC memory bank is that it can be rewritten as many times as needed. Applications that demand more storage than EPC memory employ user memory.
What is Reserved Memory?
The function of reserved memory is to lock the reading and writing activities of UHF RFID tags. That’s why applications that contain sensitive data and require a locking system for their protection use reserved memory storage. The primary purpose of reserved memory is to provide protection and shield for confidential data. It contains Access and Kill password, which are both 32 bits long. The access password is used to lock or unlock reading/writing activities, and Kill password is used to permanently block and destroy the tag’s read/write functions.
What is Tag Identifier Memory?
Tag identifier (TID) memory keeps the unique identification number of the manufacturer while constructing the ICs of the tag. This unique number differentiates one tag from another. The length of TID numbers is 32-80 bits and used to describe the category of manufacturer and chipset. The TID memory is read-only memory (ROM), which means that data can’t be changed or altered once it is written.
What is User Memory?
It is considered as a second writable memory bank in UHF RFID tags. The typical length of user memory is 512 bits; however, some of them may reach up to 4k, and 8kB depending upon the usage. The user memory becomes only useful when the user needs memory more than EPC memory.
It is optional memory storage that allows users to read already entered data, and write more data through an RFID reader. The user memory is split into multiple blocks, and access to these blocks can be made limited by locking them for particular handlers. Consequently, only authorized users can read them.
