Silan

Semiconductors

SC83702

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 1.0

2000.12.31

5

(continued)

Pin Name

I/O

Description

MS

I

microsoft mode only. If the pin is connected to Vss, then SC83702 will operate

under the mouse system mode.

However if this pin is "floating", then SC83702 is on the "power on initiation"

situation and if any one of three buttons is chosen, then SC83702 will operate under

the mouse mode. And while the whole system is on "power on initiation", no key is

chosen then operation will be under microsoft mode.

OSC.IN

I

OSC.OUT

O

A built-in inverter provides oscillation with 32.768KHz crystal or 3.58MHz resonator.

Several counters used to decrease the frequency of oscillation and create 1200

baud rate, key-switches debounce and photo-couple sensor scanning clock, etc.

RTS

I

Positive power input. The signal is sent by mouse driver from computer to the

mouse to select a mode. During the reset time, SC83702 echoes the selected mode

to the RXD line after the reset pulse signal of the RTS line. RXD will send out CD

(H) code if it is under the microsoft mode. RXD will send out two-byte C8 (H) code if

it is under the mouse system mode in SC83702.

--

Negative power input.

RI

M

I/O

L

I/O

Three key-switches exert seven different combinations totally.

Both key-pressed and key-released signals will be sent accompanied with horizontal

and vertical state. The status of the key-switches will be preserved, whenever the

value of horizontal or vertical counters will present at RXD. And the debounce

interval for both key-press and key-release is 13ms.

In testing mode, L and M are the outputs of motion detector. Using R key can select

the two outputs X1, X2 or Y1, Y2. This feature can help manufacturer to adjust the

phase of four photo-couples for improving the yield.

X1

X2

Y1

Y2

I

Four photo-couple signals denote UP, DOWN, LEFT and RIGHT state. If SC83702

is in 1200 baud rate on non-auto speed mode, the system provides 40 transmission

cycles per second in microsoft mode to the utmost. In mouse system mode, the

cycles are 24 maximum. During the scanning period, as long as the photo couples

change their states, the value of vertical or horizontal counter will increase or

decrease accordingly.

OPT

I

Whenever OPT is connected to VDD, the chip will enter testing mode.

--

Power