Silan

Semiconductors

SC84520

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 1.0

2000.12.31

8

d. Wrap Mode:

Any byte of data sent by the system. Except hex EC(Reset wrap mode) or hex FF (Reset) is returned by

SC84520.

B) PS/2 Mouse Data Report:

a. In stream mode: A data report is sent at the end of a sample interval.

b. In remote mode: A data report is sent in response to Read Data command.

c. Data report format:

Byte

Bit

Description

1

0

Left button status; 1 = pressed

1

Right button status; 1 = pressed

2

Middle button status; 1 = pressed

3

Reserve

4

X data sign; 1 = negative

5

Y data sign; 1 = negative

6

X data overflow; 1 = overflow

7

Y data overflow; 1 = overflow

2

0-7

X data ( D0 – D7)

3

0-7

Y data ( D0 – D7)

C) PS/2 Mouse Data Transmission:

a. SC84520 generates the clocking signal when sending data to and receiving data from the system.

b. The system requests SC84520 receive system data output by forcing the DATA line to an inactive level and

allowing CLKlinetogotoanactivelevel.

c. Data transmission frame:

Bit

Function

1

Start bit (always 0)

2-9

Data bits (D0 – D7)

10

Parity bit (odd parity)

11

Stop bit (always 1)

d. Data Output (data from SC84520 to system):

If CLK is low (inhibit status), data is no transmission.

If CLK is high and DATA is low (request –to-send), data is update. Data is received from the system and no

transmission are started by SC84520 until CLK and DATA both high. If CLK and DATA both are high, the

transmission is ready. DATA is valid prior to the falling edge of CLK and beyond the rising edge of CLK.

During transmission, SC84520 check for line contention by checking for an inactive level on CLK at intervals

not to exceed 100

µs, Contention occurs when the system lowers CLK to inhibit SC84520 output after