GD25VE40C datasheet(24/55 Pages) GIGADEVICE

24 / 55 page

Uniform Sector

Dual and Quad Serial Flash

GD25VE40C

Figure16. Quad I/O Word Fast Read Sequence Diagram (M7-0= AXH)

Quad I/O Word Fast Read with

“8/16/32/64-Byte Wrap Around” in Standard SPI mode

The Quad I/O Word Fast Read command can be used to access a specific portion within a page by issuing

“Set Burst

with Wrap

” (77H) commands prior to E7H. The “Set Burst with Wrap” (77H) command can either enable or disable the “Wrap

Around

” feature for the following E7H 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.

7.13.

Set Burst with Wrap (77H)

The Set Burst with Wrap command is used in conjunction with “Quad I/O Fast Read” and “Quad I/O Word Fast Read”

command to access a fixed length of 8/16/32/64-byte section within a 256-byte page.

The Set Burst with Wrap command sequence: CS# goes low  Send Set Burst with Wrap command  Send 24

dummy bits 

Send 8 bits “Wrap bits”  CS# goes high.

W6,W5

W4=0

W4=1 (default)

Wrap Around

Wrap Length

Wrap Around

Wrap Length

0, 0

Yes

8-byte

N/A

0, 1

Yes

16-byte

N/A

1, 0

Yes

32-byte

N/A

1, 1

Yes

64-byte

N/A

If the W6-

W4 bits are set by the Set Burst with Wrap command, all the following “Quad I/O Fast Read” and “Quad I/O

Word Fast Read” command will use the W6-W4 setting to access the 8/16/32/64-byte section within any page. To exit the

“Wrap Around” function and return to normal read operation, another Set Burst with Wrap command should be issued to set

W4=1.

CS#

SCLK

9 10 11 12 13 14 15

SI(IO0)

SO(IO1)

WP#(IO2)

HOLD#(IO3)

A23-16 A15-8 A7-0

M7-0 Dummy Byte1 Byte2

Byte3

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