Silan
Semiconductorsꢀ
SC84502
ꢀ
v) Data Input (from system to SC84502)
System first check if SC84502 is transmitting data. If SC84502 is transmitting, the system can override the
output forcing CLK to an inactive level prior to the tenth clock. If SC84502 transmission is beyond the tenth
clock, the system receives the data. If SC84502 is not transmitting or if the system choose to override the
output, the system force CLK to an inactive level for a period of not less than 100m sec while preparing for
output. When the system is ready to output start bit (0), it allows CLK go to active level. If request-to-send is
detected, SC84502 clocks 11 bits. Following the tenth clock SC84502 checks for an active level on the
DATA line, and if found, force DATA low , and clock once more. If occurs framing error, SC84502 continue
to clock until DATA is high, then clocks the line control bit and request a Resend. When the system sends
out a command or data transmission that requires a response, the system waits for SC84502 to response
before sending its next output.
4. PS/2 MOUSE ERROR HANDLING
i) A Resend command ( FE ) following receipt of an invalid input or any input with incorrect parity.
ii) If two invalid input are received in succession, an error code of hex FC send to the system.
iii) The counter accumulators are cleared after receiving any command except “Resend”.
iv) SC84501 receives a Resend command ( FE ), it transmit its last packet of data.
vꢀꢁIn the stream mode “Resend” is received by SC84502 following a 3-byte data packet transmission to the
system. SC84502 resend the 3-byte data packet prior to clearing the counter.
vi) A response is sent within 25 ms if
a). The system requires a response
b). An error is detected in the transmission
vii). When a command requiring a response is issued by the system ,another command should not be issue until
either the response is received or 25ms has passed.
5. PS/2 MOUSE COMMANDS DESCRIPTION
There are 16 valid commands that transmits between the system and SC84502. The “FA” code is always the
first response to any valid input received from the system other than a Set Wrap Mode or Resend command.
The following table list the commands:
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
ꢀ
2000.12.31
Rev: 1.0
ꢀ
7
SILAN [ SILAN MICROELECTRONICS JOINT-STOCK ]
