25Q64BV View Datasheet(PDF) - Winbond

Part Name

Description

Manufacturer

25Q64BV

64M-bit Serial Flash Memory with uniform 4KB sectors and Dual/Quad SPI

Winbond 

W25Q64BV

11.2.29 Continuous Read Mode Reset (FFh or FFFFh)

For Fast Read Dual/Quad I/O operations, “Continuous Read Mode” Bits (M7-0) are implemented to

further reduce instruction overhead. By setting the (M7-0) to “Ax” hex, the next Fast Read Dual/Quad I/O

operation does not require the BBh/EBh instruction code (See 11.2.12 Fast Read Dual I/O and 11.2.13

Fast Read Quad I/O for detail descriptions).

If the system controller is Reset during operation it will likely send a standard SPI instruction, such

as Read ID (9Fh) or Fast Read (0Bh), to the W25Q64BV. However, as with most SPI Serial Flash

memories, the W25Q64BV does not have a hardware Reset pin, so if Continuous Read Mode bits are set

to “Ax” hex, the W25Q64BV will not recognize any standard SPI instructions. To address this possibility, it

is recommended to issue a Continuous Read Mode Reset instruction as the first instruction after a

system Reset. Doing so will release the Continuous Read Mode from the “Ax” hex state and allow

Standard SPI instructions to be recognized. The Continuous Read Mode Reset instruction is shown in

figure 30.

/CS

CLK

IO0

IO1

IO2

IO3

Mode 3

Mode 0

Mode Bit Reset

for Quad I/O

Mode Bit Reset

for Dual I/O

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Mode 3

Mode 0

FFh

FFh

Don’t Care

Don’t Care

Don’t Care

Figure 30. Continuous Read Mode Reset for Fast Read Dual/Quad I/O

To reset “Continuous Read Mode” during Quad I/O operation, only eight clocks are needed. The

instruction is “FFh”. To reset “Continuous Read Mode” during Dual I/O operation, sixteen clocks are

needed to shift in instruction “FFFFh”.

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Publication Release Date: July 08, 2010

Revision E

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