3.3V Uniform Sector
Dual and Quad Serial Flash
GD25Q80C
7.23. 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 Figure 26. 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 26. 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
Command
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
SO
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
Memory Type
JDID15-JDID8
Capacity
JDID7-JDID0
MSB
MSB
7.24. High Performance Mode (HPM) (A3H)
The High Performance Mode (HPM) command must be executed prior to Dual or Quad I/O commands when
operating at high frequencies (see fR and fC1 in AC Electrical Characteristics). This command allows pre-charging of
internal charge pumps so the voltages required for accessing the flash memory array are readily available. The
command sequence: CS# goes lowSending A3H command Sending 3-dummy byteCS# goes high. See Figure
27. After the HPM command is executed, HPF bit of status register will be set to 1, the device will maintain a slightly
higher standby current (Icc8) than standard SPI operation. The Release from Power-Down or HPM command (ABH) can
be used to return to standard SPI standby current (Icc1). In addition, Power-Down command (B9H) will also release
the device from HPM mode back to standard SPI standby state.
31
GILWAY [ GILWAY TECHNICAL LAMP ]
