PixArt Imaging Inc.

PAN3204DB

Wireless Optical Mouse Sensor

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PixArt Imaging Inc.

E-mail: fae_service@pixart.com.tw

V3.0, Apr. 2008

6. Serial Interface

The synchronous serial port is used to set and read parameters in the mouse sensor.

SCLK: The serial clock line. It is always generated by the mouse controller.

SDIO: The serial data line is used to write and read data.

6.1 Transmission Protocol

The transmission protocol is a two-wire link, half duplex protocol between the micro-controller and the mouse

sensor. All data changes on SDIO are initiated by the falling edge on SCLK. The mouse controller always

initiates communication; the mouse sensor never initiates data transfers.

The transmission protocol consists of the two operation modes:

- Write Operation.

- Read Operation.

Both of the two operation modes consist of two bytes. The first byte contains the address (seven bits) and has a

bit 7 as its MSB to indicate data direction. The second byte contains the data.

A D D R ESS (7 BIT )

DA T A (8 B IT )

FIR S T B Y TE

S E CO ND B Y T E

MS B

LS B

R/W

(1 B IT )

MS B

LS B

Figure 7. Transmission Protocol

6.1.1 Write Operation

A write operation, which means that data is going from the mouse controller to the mouse sensor, is always

initiated by the mouse controller and consists of two bytes. The first byte contains the address (seven bits) and

has a “1” as its MSB to indicate data direction. The second byte contains the data. The transfer is synchronized

by SCLK. The mouse controller changes SDIO on falling edges of SCLK. The mouse sensor reads SDIO on

rising edges of SCLK.

SDIO driven by the mouse controller

SCLK

SDIO

12

34

5

678

10

A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0

911 12 13

14

15

A6

DON'T

CARE

1

DON'T

CARE

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Figure 8. Write Operation