AS39513 datasheet(64/108 Pages) AMSCO

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[v1-10] 2018-Apr-25

AS39513 − Detailed Description

Memory Lock Bits

The memory lock bits EEPROM pages from addresses 0x460

through 0x47F contain the individual lock status for each

EEPROM block in the Application and Measurement area. As

described above, the AS39513 has an 11-bit memory map

address space. Let the address space for the Application and

Measurement EEPROM be represented by the fields below.

Figure 41:

Address Space for the Application and Measurement EEPROM

For the Application and Memory areas, Address[10] is always 0.

These areas are broken into 256 blocks of four bytes each. The

RFID read and write commands work on a block-by-block basis.

The 8-bit block address is the concatenation: { AGROUP[4:0],

ABLSB[2:0] }. Each block can be individually locked from writing

via the RFID write commands by setting one of the memory lock

bits in the EEPROM. The EEPROM address containing the

memory lock bit for a given block is at the address 0x460 +

AGROUP. The bit index to lock the block is ABLSB. For example

to lock the block containing the memory address 0x13A, for

which AGROUP = 5’b01001, ABLSB = 3’b110, and ABYTE = 2’b10,

the RFID Lock Block command writes a 1 to bit 6 in EEPROM

address 0x469. The RFID Write Block command must check that

the corresponding lock bit is not set before writing to that

block.

The RFID interface can only access the memory lock bits

through the Lock Block command described above. They can

be read through the SPI interface. They can be written through

the SPI interface if the Factory access password has been

entered previously.

Bit

9876

Address

AGROUP[4:0]

ABLSB[2:0]

ABYTE[1:0]

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