23A1024 datasheet(14/32 Pages) MICROCHIP

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23A1024/23LC1024

DS25142A-page 14

Preliminary

 2011 Microchip Technology Inc.

4.0

DUAL AND QUAD SERIAL

MODE

The 23A1024/23LC1024 also supports SDI (Serial

Dual) and SQI (Serial Quad) mode of operation when

used with compatible master devices. As a convention

for SDI mode of operation, two bits are entered per

clock using the SIO0 and SIO1 pins. Bits are clocked

MSB first.

For SQI mode of operation, four bits of data are entered

per clock, or one nibble per clock. The nibbles are

clocked MSB first.

4.1

Dual Interface Mode

The 23A1024/23LC1024 supports Serial Dual Input

(SDI) mode of operation. To enter SDI mode the EDIO

command must be clocked in (Figure 4-1). It should be

noted that if the MCU resets before the SRAM, the user

will need to determine the serial mode of operation of

the SRAM and reset it accordingly. Byte read and write

sequence in SDI mode is shown in Figure 4-2 and

Figure 4-3.

FIGURE 4-1:

ENTER SDI MODE (EDIO) FROM SPI MODE

4.2

Quad Interface Mode

In addition to the Serial Dual interface (SDI) mode of

operation

Serial

Quad

Interface

(SQI)

also

supported. In this mode the HOLD functionality is not

available. To enter SQI mode the EQIO command must

be clocked in (Figure 4-4).

SCK

High Impedance

111

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