AT25SF321B datasheet(32/61 Pages) DIALOG

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AT25SF321B

DS-AT25SF321B–179E–06-2020

10.

Security Register Commands

The device contains three extra Security Registers pages, that can be used for unique device serialization, system-

level Electronic Serial Number (ESN) storage, locked key storage, etc. The Security Registers are independent of

the main Flash memory.

Each page of the Security Register can be erased and programmed independently. Each page can also be

independently locked to prevent further changes.

10.1 Read Unique ID Number (4Bh)

The Read Unique ID Number instruction accesses a factory-set, read-only 64-bit number that is unique to each

AT25SF321B device. The ID number can be used in conjunction with user software methods to help prevent

copying or cloning of a system. The Read Unique ID instruction is initiated by driving the CS pin low and shifting

the instruction code 4Bh, followed by four dummy byte clock cycles. After this, the 64-bit ID is shifted out on the

falling edge of SCLK, as shown in Figure 10-1.

Figure 10-1. Read Unique ID Timing (SPI Mode)

01234567

Mode 0

Mode 3

Instruction

SCK

4BH

HIGH-IMPEDANCE

Dummy Byte

Mode 0

Mode 3

SCK

100 101

102

Dummy Byte 3

Dummy Byte 4

64- bit Unique

Serial Number

MSB

103

HIGH-IMPEDANCE

AT25SF321B 데이터시트(PDF) 32 Page - Dialog Semiconductor