GD25LQ40xIGx 1.8V Uniform Sector Dual and Quad Serial Flash
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7.25. Read Identification (RDID) (9FH)
The Read Identification (RDID) command allows the 8-bit manufacturer identification to be read, followed by
two bytes of device identification. The device identification indicates the memory type in the first byte, and the
memory capacity of the device in the second byte. The Read Identification (RDID) command while an Erase
or Program cycle is in progress, is not decoded, and has no effect on the cycle that is in progress. The Read
Identification (RDID) command should not be issued while the device is in Deep Power-Down Mode.
The device is first selected by driving CS# to low. Then, the 8-bit command code for the command is shifted
in. This is followed by the 24-bit device identification, stored in the memory, being shifted out on Serial Data
Output, each bit being shifted out during the falling edge of Serial Clock. The command sequence is shown in
Figure27. The Read Identification (RDID) command is terminated by driving CS# to high at any time during
data output. When CS# is driven high, the device is put in the Standby Mode. Once in the Standby Mode, the
device waits to be selected, so that it can receive, decode and execute commands.
Figure 27. Read Identification ID Sequence Diagram
CS#
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
SCLK
SI
9FH
Manufacturer ID
7
6
5
4
3
2
1
0
SO
MSB
CS#
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SCLK
SI
Memory Type ID15-ID8
Capacity ID7-ID0
SO
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
MSB
MSB
Figure 27a. Read Identification ID Sequence Diagram (QPI)
CS#
0
1
2
3
4
5
6
SCLK
IOs switch from
Input to Output
Command
9FH
4
0
12
8
4
0
1
2
3
IO0
5
1
2
3
13
9
5
IO1
IO2
IO3
6
14 10
15 11
6
7
7
MID ID15-8 ID7-0
Rev.1.0
59 - 40
ELM [ ELM ELECTRONICS ]
