AT45DB642D datasheet(39/55 Pages) ATMEL

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3542F–DFLASH–09/06

AT45DB642D

21.8

Utilizing the Rapid8™ Function

The Rapid8 functions like RapidS but with 8 bits of data instead of 1 bit. A full clock cycle must

be used to transmit data back and forth across the 8 bit bus. The DataFlash is designed to

always clock its data out on the falling edge of the SCK signal and clock data in on the rising

edge of SCK.

For full clock cycle operation to be achieved, when the DataFlash is clocking data out on the fall-

ing edge of SCK, the host controller should wait until the next falling edge of SCK to latch the

data in. Similarly, the host controller should clock its data out on the rising edge of SCK in order

to give the DataFlash a full clock cycle to latch the incoming data in on the next rising edge of

SCK.

Figure 21-2. Rapid8 Mode

21.9

Reset Timing

Note:

The CS signal should be in the high state before the RESET signal is deasserted.

SCK

I/O

7-0

234567

101112131415

MOSI = Master Out, Slave In

MISO = Master In, Slave Out

The Master would be the ASIC/MCU and the Slave would be the memory device.

The Master always clocks data out on the rising edge of SCK and always clocks data in on the falling edge of SCK.

The Slave always clocks data out on the falling edge of SCK and always clocks data in on the rising edge of SCK.

Master clocks out BYTE 1 on the rising edge of SCK.

Slave clocks in BYTE 1 on the next rising edge of SCK.

Master clocks out BYTE 2 on the same rising edge of SCK.

Slave clocks in BYTE 6 (last input byte).

Slave clocks out BYTE a (first output byte).

Master clocks in BYTE a.

Master clocks in BYTE h (last output byte).

Slave

BYTE 6

BYTE 5

BYTE 4

BYTE 3

BYTE 2

BYTE 1

BYTE a

BYTE b

BYTE c

BYTE d

BYTE e

BYTE f

BYTE g

BYTE h

SCK/CLK

RESET

SO or I/O7 - I/O0

(OUTPUT)

HIGH IMPEDANCE

SI or I/O7 - I/O0

(INPUT)

tRST

tREC

tCSS

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