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GD25LQ256 Datasheet, PDF (29/68 Pages) ELM Electronics – 1.8V Uniform Sector Dual and Quad Serial Flash | |||
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GD25LQ256CWIGx 1.8V Uniform Sector Dual and Quad Serial Flash
http://www.elm-tech.com
Quad I/O Fast Read with â8/16/32/64-Byte Wrap Aroundâ in Standard SPI mode
The Quad I/O Fast Read command can be used to access a specific portion within a page by issuing âSet Burst
with Wrapâ (77H) commands prior to EBH. The âSet Burst with Wrapâ (77H) command can either enable or
disable the âWrap Aroundâ feature for the following EBH commands. When âWrap Aroundâ 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 âSet Burst with Wrapâ command allows three âWrap Bitsâ W6-W4 to be set. The W4 bit is used to enable
or disable the âWrap Aroundâ 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 Figure14b. In QPI mode, the number
of dummy clocks is configured by the âSet Read Parameters (C0H)â 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 âContinuous Read Modeâ bits M7-M0 are also considered as dummy clocks.
âContinuous Read Modeâ feature is also available in QPI mode for Quad I/O Fast Read command. âWrap
Aroundâ 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 âBurst Read with Wrapâ (0CH) command must be
used.
Figure 14b. 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
IOs switch from
Input to output
20 16 12 8 4 0 4 0 4 0 4 0 4
21 17 13 9 5 1 5 1 5 1 5 1 5
22 18 14 10 6 2 6 2 6 2 6 2 6
23 19 15 11 7 3 7 3 7 3 7 3 7
A23-16 A15-8 A7-0 M7-0* Byte1 Byte2 Byte3
*"Set Read Parameters"
Command (C0H) can
set the number of
dummy clocks
Note: The device default is in 24-bit address mode. For 4-byte mode, the address length becomes 32-bit.
68 - 29
Rev.1.0
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