The memory configuration of an RF300 tag always comprises an EEPROM memory that has
20 bytes for user data (read/write) and a 4 byte unique serial number (UID, read only). For
reasons of standardization, the UID is transferred as an 8 byte value through a read
command to address FFF0 with a length of 8. The unused 4 high bytes are filled with zeros.
The EEPROM user memory (address FF00-FF13, or FF80-FF90) requires significantly more
time for writing (approx. 11 ms/byte) than the high-speed FRAM memory. For time-critical
applications with a write function, it is therefore recommended that FRAM tags are used (e.g.
RF340T, RF350T, RF360T, RF370T, RF380T).
Depending on the tag type, high-speed FRAM memory is available. (8 KB, 32 KB, 64 KB).
This area does not exist for the RF320T.
The EEPROM memory area (address FF00-FF13) can also be used as a so-called "OTP"
memory (One Time Programmable). The 5 block addresses FF80, FF84, FF88, FF8C and
FF90 are used for this purpose. A write command to this block address with a valid length (4,
8, 12, 16, 20 depending on the block address) protects the written data from subsequent
The OTP area cannot be used for the IQ-Sense reader variant.
Seamless use of the OTP area
When the OTP area is used, it must be ensured that the blocks are used starting from Block
3 blocks (with write command), Block 0, 1, 2 (FF80, length = 12): valid
2 blocks (consecutive), Block 0 (FF80, length =4), Block 1 (FF84, length = 4): valid
2 blocks (consecutive), Block 0 (FF80, length =4), Block 2 (FF88, length = 4): Invalid
1 Block, Block 4 (FF90, length = 4): Invalid
System Manual, 01/2009, A5E01642529-03
6.2 Memory configuration of the RF300 tags