W25X05CL Datasheet, PDF (34/51 Pages) Winbond – 2.5 / 3 / 3.3 V 512K / 1M / 2M-BIT SERIAL FLASH MEMORY WITH 4KB SECTORS AND DUAL I/O SPI

W25X05CL/10CL/20CL
8.2.23 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 W25X05CL/10CL/20CL 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 a four bytes of dummy
clocks. After which, the 64-bit ID is shifted out on the falling edge of CLK as shown in figure 24.
/CS
CLK
Mode 3
Mode 0
DI
(IO₀)
DO
(IO₁)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Instruction (4Bh)
Dummy Byte 1
Dummy Byte 2
High Impedance
/CS
CLK
DI
(IO₀)
DO
(IO₁)
23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
Dummy Byte 3
Dummy Byte 4
* ^{= MSB}
High Impedance
63 62 61
210
* 64-bit Unique Serial Number
Mode 3
Mode 0
Figure 24. Read Unique ID Number Instruction Sequence
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Publication Release Date: March 23, 2012
Revision B