GD25Q128C Datasheet, PDF (27/69 Pages) ELM Electronics – 128M-bit Serial Flash

GD25Q128CxIGx 3.3V Uniform Sector Dual and Quad Serial Flash
http://www.elm-tech.com
Quad I/O Fast Read with “8/16/32/64-Byte Wrap Around” in Standard SPI mode
The Quad I/O Fast Read command can be used to access a specific portion within a page by issuing “Set Burst
with Wrap” (77H) commands prior to EBH. The “Set Burst with Wrap” (77H) command can either enable or
disable the “Wrap Around” feature for the following EBH commands. When “Wrap Around” is enabled, the
data being accessed can be limited to either an 8/16/32/64-byte section of a 256-byte page. The output data
starts at the initial address specified in the command, once it reaches the ending boundary of the 8/16/32/64-byte
section, the output will wrap around the beginning boundary automatically until CS# is pulled high to terminate
the command.
The Burst with Wrap feature allows applications that use cache to quickly fetch a critical address and then fill
the cache afterwards within a fixed length (8/16/32/64-byte) of data without issuing multiple read commands.
The “Set Burst with Wrap” command allows three “Wrap Bits” W6-W4 to be set. The W4 bit is used to enable
or disable the “Wrap Around” operation while W6-W5 is used to specify the length of the wrap around section
within a page.
Quad I/O Fast Read (EBH) in QPI mode
The Quad I/O Fast Read command is also supported in QPI mode. See Figure13b. In QPI mode, the number
of dummy clocks is configured by the “Set Read Parameters (C0H)” command to accommodate a wide range
application with different needs for either maximum Fast Read frequency or minimum data access latency.
Depending on the Read Parameter Bits P[5:4] setting, the number of dummy clocks can be configured as
either 4/6/8/8. In QPI mode, the “Continuous Read Mode” bits M7-M0 are also considered as dummy clocks.
“Continuous Read Mode” feature is also available in QPI mode for Quad I/O Fast Read command. “Wrap
Around” feature is not available in QPI mode for Quad I/O Fast Read command. To perform a read operation
with fixed data length wrap around in QPI mode, a dedicated “Burst Read with Wrap” (0CH) command must be
used.
Figure 13b. Quad I/O Fast Read Sequence Diagram (M5-4 = (1, 0) QPI)
CS#
SCLK
IO₀
IO₁
IO₂
IO₃
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Command
EBH
20 16 12 8 4 0 4
IOs switch from
Input to output
4 04 0 4
21 17 13 9 5 1 5
5 15 1 5
22 18 14 10 6 2 6
6 26 2 6
23 19 15 11 7 3 7
7 37 3 7
A23-16 A15-8
A7-0
Dummy
M7-4*
Byte1
Byte2
Byte3
*"Set Read Parameters"
Command (C0H) can
set the number of
dummy clocks
69 - 27
Rev.1.2