The EM83702 Mouse Controller is specially designed to control mouse device. This single chip can interface
three key-switches and four photo-couple direct to RS-232C. The EM83702 does not need any external power
supply,so the mouse can go without a power line. It is versatile with both microsoft and mouse system.
Debouncing circuit were provided to prevent false entry and to improve the accuracy. In 1200 baud rate non-auto
speed with 200 DPI wheels and photo-couples, the scanning is 650 mm/sec without missing a dot in microsoft
mode,and the scanning speed can up to 770 mm/sec in mouse system mode.
FEATURES
• Built-in two zener diode between VDD and VSS, RTS and VDD.
• Buit-in noise immunity circuit.
• CMOS DIP 16 pins package & SOP 16 pins package.
• Low power dissipation.
• Use 32.768 kHz crystal or 3.58MHz resonator.
• Oscillator circuits on-chip.
• Serial output in 1200 baud rate.
• Can be powered directly from RS-232C.
• Can drive directly to RS-232C.
• Three key-switches and four photo-couples inputs.
• Both key-in and key-release debounce interval 13 ms.
• Through three key-switches input, EM83702 can exert seven different output.
* This specification are subject to be changed without notice.
4.15.1996
1
PIN ASSIGNMENTS
EM83702
ALL IN ONE MOUSE CONTROLLER
EM83702A
RS
1
MS
OSC.IN
OSC.OUT
RTS
RXD
VSS
R
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
FUNCTIONAL BLOCK DIAGRAM
OPT
OSC.OUT
OSC.IN
RTS
X1
X2
Y1
Y2
L
M
R
MS
RS
D
M
E
N
M
M
T
O
O
U
E
I
T
N
C
S
I
T
E
O
T
O
N
Y
R
D
E
B
O
U
N
C
E
V
DD
OPT
Y2
Y1
X2
X1
L
M
I
I
SYSTEM CLOCK
GENERATOR
COUNTER
MODE
SELECTOR
RS
OPT
MS
OSC.IN
OSC.OUT
RTS
RXD
VSS
MULTIPLEXER
EM83702B
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
CONTROLLER
LEVEL-SHIFT
CIRCUIT
V
DD
Y2
Y1
X2
X1
L
M
R
P/S
TIMING
RXD
PIN DESCRIPTIONS
Symbol I/OFunction
RSICrystal type select : "0" or floating, select 32.768KHz crystal. "1" select 3.58MHz
resonator.
MSIWhen this pin is connected to V
under the microsoft mode only. If the pin is connected to V
will operate under the mouse system mode.
However if this pin is "floating", then EM83702 is on the “power on initiation”
situation and if any one of three buttons is chosen, thence EM83702 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.INIA built-in inverter provides oscillation with 32.768 KHz crystal or 3.58MHz
OSC.OUTresonator.
Several counters used to decrease the frequency of oscillation and create 1200 baud
rate, key-switches debounce and photo-couple sensor scanning clock,etc.
RTSIPositive power input.
The signal is sent by mouse driver from computer to the mouse to select
a mode. During the reset time, EM83702 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 EM83702.
, then EM83702 is assigned to operate
DD
, then EM83702
SS
* This specification are subject to be changed without notice.
4.15.1996
2
EM83702
ALL IN ONE MOUSE CONTROLLER
Symbol I/OFunction
RXDOThere are 8 or 7 bits in each data byte.
Using parallel-in and serial-out components, the data bytes are shifted out from bit
0 through the high bits. EM83702 will transmit the data while the status of three
keyswitches or the state of the horizontal counter or vertical counter is changed.
V
SS
Negative power input.
RIThree key-switches exert seven different combinations totally.
MI/OBoth key-pressed and key-released signals will be sent accomplanied with
LI/Ohorizontal 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 13 ms.
In testing mode, L and M are the outputs of motion detecdor. 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.
X1IFour photo-couple signals denote UP, DOWN, LEFT and RIGHT state. If
X2EM83702 is in 1200 baud rate on non-auto speed mode, the system provides 40
Y1transmission cycles per second in microsoft mode to the utmost. In mouse system
Y2mode, the cycles are 24 maxiun. 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.
OPTIWhenever OPT is connected to V
V
DD
Power.
, the chip will enter testing mode.
DD
FUNCTION DESCRIPTIONS
A) Operating Mode
Mouse system mode
Anytime the mouse changes its state, including the key-switches and the photo-couple sensors, EM83702 will
detect the result and transmit to RS-232C. Mouse system transmits the result with five bytes in 1200 baud
rate. Each byte contains 10 bits, one start bit, one stop bit and eight data bits. The first byte represents
the key-switches status. The second byte denote the number counted by the horizontal counter. The third byte
conveys the number accumulated by the vertical counter. If the mouse is moved faster, the photo-couple
sensors detect the “change state” and output the record, excessive horizontal counter will be transported
through the fourth byte, and vertical counter through the fifth byte. Otherwise, the fourth and fifth byte are zero.
Output bytes arrange:
bitno ......7654321 0
1stbyte......10000L’M’R’*
2ndbyte......H7H6H5H4H3H2H1H0
3rdbyte......V7V6V5V4V3V2V1V0
4thbyte......H7H6H5H4H3H2H1H0
5thbyte......V7V6V5V4V3V2V1V0
* ‘ denotes complement
* This specification are subject to be changed without notice.
4.15.1996
3
EM83702
ALL IN ONE MOUSE CONTROLLER
(B) Microsoft mode
In microsoft mode, the transmission cycle consists of three bytes. Each byte is divided into one start bit, seven
data bits and two stop bit. The first byte contains “L”,”R” switch status and four bits of the two most significant bits in horizontal counter and vertical counter. The next byte represents the value accumulated by
horizontal counter, the last byte is the data of the vertical counter. Notice that “M” key-switch is not active
in the microsoft mode and the vertical data is transmited in 2’s complement.
Output byte arrange:
bitno ......6543210
1stbyte......1LRV7'V6'H7 H6
2ndbyte......0H5H4H3H2H1H0
3rdbyte......0V5'V4'V3'V2'V1'V0'
(C) Testing mode
Whenever OPT is connected to VDD, the chip will enter buyer’s testing mode. The X direction output signals
of comparators will present to L and M pin. Pressing “R” key can toggle the output from X direction to Y
direction.
(D) Echo mode
RXD will send out CD(H) code when RTS rise from low to high under microsoft mode. Under mouse
system mode, when RTS rise from low to high, the RXD pin EM83702 will send out two byte C8(H) code.
* This specification are subject to be changed without notice.
4.15.1996
4
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