W25Q64FV
7.2.33
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 W25Q64FV 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 32.
/CS
Mode 3
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
CLK
Mode 0
Instruction (4Bh)
DI
(IO
0
)
DO
(IO
1
)
Dummy Byte 1
Dummy Byte 2
High Impedance
/CS
100
101
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
102
Mode 3
Mode 0
CLK
Dummy Byte 3
DI
(IO
0
)
DO
(IO
1
)
High Impedance
63
62
61
2
1
0
Dummy Byte 4
*
= MSB
*
64-bit Unique Serial Number
Figure 32. Read Unique ID Number Instruction (SPI Mode only)
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