GD25LQ40xIGx 1.8V Uniform Sector Dual and Quad Serial Flash
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7.30. Read Security Registers (48H)
The Read Security Registers command is similar to Fast Read command. The command is followed by a
3-byte address (A23-A0) and a dummy byte, each bit being latched-in during the rising edge of SCLK. Then
the memory content, at that address, is shifted out on SO, each bit being shifted out, at a Max frequency fC,
during the falling edge of SCLK. The first byte addressed can be at any location. The address is automatically
incremented to the next higher address after each byte of data is shifted out. Once the A9-A0 address reaches the
last byte of the register (Byte 3FFH), it will reset to 000H, the command is completed by driving CS# high.
Address
A23-16
A15-12
A11-8
A7-0
Security Register #0
Security Register #1
Security Register #2
Security Register #3
00H
00H
00H
00H
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
Byte Address
Byte Address
Byte Address
Byte Address
Figure 32. Read Security Registers command Sequence Diagram
CS#
0
1
2
3
4
5
6
7
8
9 10
28 29 30 31
SCLK
SI
Command
48H
24-bit address
23 22 21
3
2
1
0
High-Z
SO
CS#
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Dummy Byte
SCLK
SI
7
6
5
4
3
2
1
0
Data Out1
Data Out2
SO
7
6
5
4
3
2
1
0
7
6
5
MSB
MSB
Rev.1.0
59 - 45
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