ACE25QC800GLMMTH datasheet(29/58 Pages) ACE

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ACE25QC800G

8M BIT SPI NOR FLASH

VER 1.2

Quad I/O Word Fast Read with “8/16/32/64-Byte Wrap Around” in standard SPI mode

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

“Set Burst with Wrap” (77H) instruction prior to E7H. The “Set Burst with Wrap” (77H) instruction can either

enable or disable the “Wrap Around” feature for the following E7H instructions. When “Wrap Around” is

enabled, the data being accessed can be limited to either an 8, 16, 32 or 64-byte section of a 256-byte

page. The output data starts at the initial address specified in the instruction, once it reaches the ending

boundary of the 8/16/32/64-byte section, the output will wrap around to the beginning boundary

automatically until /CS is pulled high to terminate the instruction.

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

instructions.

The “Set Burst with Wrap” instruction allows three “Wrap Bits”, W6-4 to be set. The W4 bit is used to enable

or disable the “Wrap Around” operation while W6-5 are used to specify the length of the wrap around

section within a page.

Set Burst with Wrap (77H)

See Figure 17, The Set Burst with Wrap instruction is used in conjunction with “Quad I/O Fast Read” and

“Quad I/O Word Fast Read” instruction to access a fixed length of 8/16/32/64-byte section within a 256-byte

page, in standard SPI mode.

The Set Burst with Wrap instruction sequence:/CS goes low ->Send Set Burst with Wrap instruction

->Send24 Dummy bits ->Send 8 bits “Wrap bits”->/CS goes high.

If W6-4 is set by a Set Burst with Wrap instruction, all the following “Fast Read Quad I/O” and “Word Read

Quad I/O” instructions will use the W6-4 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

instruction should be issued to set W4=1. The default value of W4 upon power on is 1.

W4 = 0

W4 =1 (DEFAULT)

Wrap Around

Wrap Length

Wrap Around

Wrap Length

Yes

8-byte

N/A

Yes

16-byte

N/A

Yes

32-byte

N/A

Yes

64-byte

N/A

Figure17. Set Burst with Wrap Sequence Diagram

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