GD25LB128DSJS datasheet(28/75 Pages) GIGADEVICE

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1.8V Uniform Sector

Dual and Quad Serial Flash

GD25LB128D

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 Figure12b. 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.



Figure12b. Quad I/O Fast Read Sequence Diagram (M5-4= (1, 0) QPI)

CS#

SCLK

IO0

IO1

IO2

IO3

Command

EBH

A23-16

A15-8

A7-0

M7-0*

12 13

IOs switch from

Input to output

dummy* Byte1

Byte2

*"Set Read Parameters"

Command (C0H) can

set the number of

dummy clocks

GD25LB128DSJS Datasheet(PDF) 28 Page - GigaDevice Semiconductor (Beijing) Inc.

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