AT25SL321 datasheet(52/82 Pages) DIALOG

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AT25SL321

DS-25SL321–112H–2020-10

Wrap Around in SPI mode

The Word Read Quad I/O 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 commands. When Wrap Around is enabled, 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 wraps 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 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 is used to specify the length of the wrap around section within a

page. See

8.32 Set Burst with Wrap (77h)

The Set Burst with Wrap (77h) instruction is used in conjunction with Fast Read Quad I/O and Word Read

Quad I/O instructions to access a fixed length of 8/16/32/64-byte section within a 256-byte page. Certain

applications can benefit from this feature and improve the overall system code execution performance. Before the

device accepts the Set Burst with Wrap instruction, a Quad enable of Status Register-2 must be set (Status

The Set Burst with Wrap instruction is initiated by driving the CS pin low and then shifting the instruction code

77h followed by 24 dummy bits and 8 Wrap Bits, W7-0. The instruction sequence is shown in Set Burst with Wrap

Instruction Sequence. Wrap bit W7 and W3-0 are not used.

Once 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 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, issue to set W4=1, another Set Burst with Wrap instruction.

The default value of W4 upon power on is 1. In the case of a system Reset while W4 = 0, it is recommended that

the controller issues a Set Burst with Wrap instruction or Reset (99h) instruction to reset W4 = 1 prior to any

normal Read instructions since AT25SL321 does not have a hardware Reset Pin.

Table 8-6.

Set Burst with Wrap W6:W4 Encoding

W6, W5

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

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