DS1305

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3-WIRE INTERFACE

The 3-wire interface mode operates similarly to the SPI mode. However, in 3-wire mode there is one I/O

instead of separate data in and data out signals. The 3-wire interface consists of the I/O (SDI and SDO

pins tied together), CE and SCLK pins. In 3-wire mode, each byte is shifted in LSB first unlike SPI mode

where each byte is shifted in MSB first.

As is the case with the SPI mode, an address byte is written to the device followed by a single data byte

or multiple data bytes. Figure 10 illustrates a read and write cycle. In 3-wire mode, data is input on the

rising edge of SCLK and output on the falling edge of SCLK.

3-WIRE SINGLE-BYTE TRANSFER Figure 10

Single Byte Read

Single Byte Write

In burst mode, RST is kept high and additional SCLK cycles are sent until the end of the burst.

* I/O is SDI and SDO tied together

RST

SCLK

I/O

A0 A1

A2

A3

A4

A5 A6

A7

RST

SCLK

I/O

D0

D1

D2

D3

D4

D5

D6 D7

A0 A1

A2

A3

A4

A5 A6

A7