FM25D04C-1AIB4T View Datasheet(PDF) - FIDELIX

Part Name

Description

Manufacturer

FM25D04C-1AIB4T

32M-BIT Serial Flash Memory with 4KB Sectors, Dual and QuadI/O SPI

FIDELIX 

FM25Q32

11.2.26 Mode Bit Reset (FFh)

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

instruction overhead. By setting the Mode Bits (M7-0) to “Ax” hex, the next Fast Read Dual/Quad

I/O operations do not require the BBh/EBh instruction code (See 11.2.10 Fast Read Dual I/O and

11.2.11 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 FM25Q32. However, as with most SPI Serial Flash

memories, the FM25Q32 does not have a hardware Reset pin, so if Mode bits are set to “Ax” hex,

the FM25Q32 will not recognize any standard SPI instruction. To address this possibility, it is

recommended to issue a Mode Bit Reset instruction “FFh” as the first instruction after a system

Reset. Doing so will release the mode Bits for the “Ax” hex state and allow Standard SPI instruction

to be recognized. The Mode Bits Reset instruction is shown in figure 26.

/CS

Mode 3

CLK

Mode 0

IO0

IO1

IO2

IO3

0 1 2 3 4 5 6 7 Mode3

Mode 0

Instruction(FFh)

Don’t Care

Don’t Care

Don’t Care

Figure 26. Mode Bits Reset for Fast Read Dual/Quad I/O

preliminary(Aug.18.2010) 44

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