Rainbow-electronics DS1305 Manuel d'utilisateur télécharger pdf (Page 14)

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 9 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.

Figure 9. 3-WIRE SINGLE-BYTE TRANSFER

Single-Byte Read

Single-Byte Write

In burst mode, CE

is kept high and additional SCLK cycles are sent until the end of the burst.

*I/O is SDI and SDO tied together.

D0 D1 D2 D3 D4 D5 D6 D7

0 A1 A2 A3 A4 A5 A6 0

I/O*

SCLK

A0 A1 A2 A3 A4 A5 A6 1

SCLK

I/O*

D0 D1 D2 D3 D4 D5 D6 D7

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 20

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Rainbow-electronics DS1305 Manuel d'utilisateur Page 14