EM84502
PS/2 MOUSE CONTROLLER
FUNCTIONAL BLOCK DIAGRAM
OP
D
E
I
X1
M
M
U
N
IT
Y
COUNTER
M
O
T
I
O
N
N
O
I
S
E
T
E
C
T
O
R
X2
Y1
Y2
C
O
N
V
E
R
T
E
R
D
E
C
O
D
E
C
D
E
L
O
M
M
A
N
D
D
A
T
B
O
U
N
C
E
TIMING
CONTROLLER
M
R
A
R
OSCR
SYSTEM
CLOCK
GENERATOR
DATA
I/O
DATA
CLK
OSC OUT
PIN DESCRIPTIONS
Symbol
VDD
I/O
Function
Power
X, Y inputs.
OP
I
Floating : Comparator input.
GND : Schmitt trigger input.
Short to OSC OUT : Testing Mode.
Clock output.
OSCOUT
CLK
O
I/O
I/O
8042 auxiliary port CLK line.
8042 auxiliary port DATA line.
Ground
Three key-switches exert seven different combinations totally. Both key-pressed
and key-released signals will be sent accomplanied 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 DATA. And the debounce interval
for both key-press and key-release is 12 ms.
DATA
VSS
R
M
L
I
X1
X2
Y1
Y2
I
I
Four photo-couple signals denote UP, DOWN, LEFT, and RIGHT state.
During the scaning period, as long as the photo-couples change their states, the
value of vertical or horizontal counter will increase or decrease accordingly.
OSCR
30 Kohm ±5% pull low for 35 KHz oscillation.
FUNCTION DESCRIPTIONS
A) Operating mode
There are four operating modes in PS/2 mouse:
i). Reset Mode:
In this mode a self-test is initiated during power-on or by a Reset command. After reset signal, PS/2
mouse will send:
1). Completion code AA & ID code 00.
6.18.1998
* This specification are subject to be changed without notice.
2
ELAN [ ELAN MICROELECTRONICS CORP ]
