The EM84510 Scrolling Mouse Controller is specially designed to control PS/2 mouse device. This single chip
can interface three key-switches four photo-couples plus z-axis direct to 8042 controller.
EM84510 can receive command and echo status or data format which are compatible with IBM PS/2 mode
mouse.
Key debouncing circuit is provided to prevent false entry and improve the accuracy.
In the traditional mouse, a great number of noises are generated when the grid is partially closed or opened. These
noises are usually mistaken for movement signals by traditional mouse controller and the cursor of the dispaly
screen is thus moved frequently up and down or back and forth. This will consume a great amount of energy.
The EM84510 mouse controller provides noise immunity circuits to eliminat these noise in order to reduce
energy consumption.
FEATURES
• Using 51k ±5% resistor for RC oscillation.
• Compatible with legacy PS/2 mouse.
• Compatible with Microsoft scrolling mouse.
• Built-in noise immunity circuit.
• Built-in current comparator for photo-couples input.
• Built-in three step dynamic input impedance.
• Three key-switches and four photo-couples inputs.
* This specification are subject to be changed without notice.
1
16
2
3
4
5
6
7
8
OSCR
15
Y2
14
Y1
13
X2
12
X1
11
L
10
M
9
R
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FUNCTIONAL BLOCK DIAGRAM
EM84510
PS/2 SCROLLING MOUSE CONTROLLER
THREE TYPES SELECTOR
VOLTAGE
SENSOR
Z-AXIS COUNTER
MULTIPLEXER
COMMON
STATUS
SYSTEM CLOCK
GENERATOR
RC
OSCILLATION
KEY-SWITCH
DETECTOR
DATA
DATA
I/O
TIMING
CONTROLLER
CLK
OPT
Z1
Z2
C
D
O
M
E
M
O
X1
X2
Y1
Y2
L
M
R
P
A
R
A
T
O
R
OSC.OUT
D
E
B
O
U
N
C
E
T
T
E
I
C
O
T
N
O
R
OSCR
COMPARATOR
COUNTER
PIN DESCRIPTIONS
Symbol I/OFunction
OPTI/OINPUT: 200kohm pull low to VSS.
When OPT is connected to VDD, EM84510 will enter test mode. In test mode,
L will be the output of X1,while M will be the output of X2. Toggling R key can
change these output to be Y1,Y2 or Z1,Z2 respectively.
OUTPUT: 2kHz Z-axis LED driving source.
"1"= VDD, "0"= floating
High duty is about 60us.
OSC.OUTORC mode oscillation with 51kohm resistor.
OSCR I
CLKI/OConnect to 8042 auxiliary port CLK line.
DATAI/OConnect to 8042 auxiliary port DATA line.
R/M/LIThree key-switches inputs.
200kohm resistor pull low.
X1IThree step dynamic input impedance.
X2Use current comparator to measure photo-couples "ON" ,or "OFF".
Y1
Y2
Z1Z-axis inputs.
Z2Photo mode: Three step dynamic input impedance. Current comparator input.
7Y data overflow; 1 = overflow
20-7X data ( D0 - D7 )
30-7Y data ( D0 - D7 )
* This specification are subject to be changed without notice.
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EM84510
PS/2 SCROLLING MOUSE CONTROLLER
C) PS/2 mouse Data Transmission:
i). EM84510 generates the clocking signal when sending data to and receiving data from the system.
ii). The system requests EM84510 receive system data output by forcing the DATA line to an inactive
level and allowing CLK line to go to an active level.
iii). Data transmission frame:
BitFunction
1Start bit ( always 0 )
2-9Data bits ( D0 - D7 )
10Parity bit ( odd parity )
11Stop bit ( always 1 )
iv). Data Output ( data from EM84510 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 updated. Data is received from the system
and no transmission are started by EM84510 until CLK and DATA both high. If CLK and DATA are both
high, the transmission is ready. DATA is valid prior to the falling edge of CLK and beyond the rising edge
of CLK. During transmission, EM84510 check for line contention by checking for an inactive level on CLK
at intervals not to exceed 100u sec. Contention occurs when the system lowers CLK to inhibit EM84510
output after EM84510 has started a transmission. If this occurs before the rising edge of the tenth clock,
EM84510 internal store its data in its buffer and returns DATA and CLK to an active level. If the contention
does not occur by the tenth clock, the transmission is complete.
Following a transmission, the system inhibits EM84510 by holding CLK low until it can service the input
or until the system receives a request to send a response from EM84510.
v). Data Input ( from system to EM84510 ):
System first check if EM84510 is transmitting data. If EM84510 is transmitting, the system can override
the output forcing CLK to an inactive level prior to the tenth clock. If EM84510 transmission is beyond
the tenth clock, the system receives the data. If EM84510 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 100µ 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, EM84510 clocks 11 bits. Following the tenth clock EM84510 checks for
an active level on the DATA line, and if found, force DATA low , and clock once more. If occurs framing
error, EM84510 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 EM84510 to response before sending its next output.
D). 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.
* This specification are subject to be changed without notice.
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EM84510
PS/2 SCROLLING MOUSE CONTROLLER
iii). The counter accumulators are cleared after receiving any command except “Resend”.
iv). EM84510 receives a Resend command ( FE ), it transmit its last packet of data.
v). In the stream mode “Resend” is received by EM84510 following a 3-byte data packet transmission
to the system. EM84510 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.
E). PS/2 Mouse Commands Description:
There are 16 valid commands that transmits between the system and EM84510. 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:
* This specification are subject to be changed without notice.
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EM84510
PS/2 SCROLLING MOUSE CONTROLLER
stream mode
2 dots/count
disable
b). Resend ( FE )
i). Any time EM84510 receives an invalid command, it returns a Resend command to the system.
ii). When EM84510 receives a Resend command, it retransmits its last packet of data. If the last packet was
a Resend command, it transmits the packet just prior to the Resend command.
iii). In stream mode, if a Resend command is received by EM84510 immediately following a 3-byte data
packet transmission to the system.
c). Set Default ( F6 )
The command reinitializes all conditions to the power-on defaults.
d). Disable ( F5 )
This command is used in the stream mode to stop transmissions from EM84510.
e). Enable ( F4 )
Begins transmissions, if in stream mode.
f). Set Sampling Rate ( F3,XX )
In the stream mode, this command sets the sampling rate to the value indicated by byte hex XX,
shown in following:
Second byte XXSample Rate
0A10/sec
1420/sec
2840/sec
3C60/sec
5080/sec
64100/sec
C8200/sec
g). Read Device Type ( F2 )
EM84510 always echoes “ FA,00 “ following this command.
h). Set Remote Mode ( F0 )
Data value are reported only in response to a Read Data command.
i). Set Wrap Mode ( EE )
Wrap mode remains until Reset ( FF ) or Reset Wrap Mode( EC ) is received.
j). Reset Wrap Mode ( EC )
EM84510 returns to the previous mode of operation after receiving this command.
k). Read Data ( EB )
This command is executed in either remote or stream mode. The data is transmitted even if there has been
no movement since the last report or the button status is unchanged. Following a Read Data command,
the registers are cleared after a data transmission.
* This specification are subject to be changed without notice.
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PS/2 SCROLLING MOUSE CONTROLLER
l). Set Stream Mode ( EA )
This command sets EM84510 in stream mode.
m). Status Request ( E9 )
When this command is issued by the system, EM84510 respond with a 3-byte status report as follows:
EM84510 provides four resolutions selected by the second byte of this command as follows:
Second Byte XXResolution
008 dot/count
014 dot/count
022 dot/count
031 dot/count
o). Set Autospeed ( E7 )
At the end of a sample interval in the stream mode, the current X and Y data values are converted new values.
The sign bits are not involved in this conversion. The conversion is only in stream mode. The relationship
between the input and output count follows:
InputOuput
00
11
21
33
46
59
N(≥6 )2.0*N
p).Reset Autospeed ( E6 )
This command restore normal speed.
* This specification are subject to be changed without notice.
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PS/2 SCROLLING MOUSE CONTROLLER
Microsoft PS/2 scrolling mouse mode:
(A) Entering procedure: Except in WRAP mode, while EM84510 received the following consecutive
command.
i. F3 C8---- set sampling rate 200/sec
ii. F3 64---- set sampling rate 100/sec
iii. F3 50---- set sampling rate 80/sec
(B) Operating:
a. All of the commands in legacy mode still be valid.
b. The ID code of read device type command (F2) will changed from "00" to be "03".
c. Data report will be four bytes format:
Byte Bit Description
10 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 )
4 0-7 Z data ( D0 - D7 )
EM84510
(C) Exiting Microsoft scrolling mode:
There are two ways to exit:
a. Power off.
b. Reset command (FF).
Z-axis Input Function : The Z0-Z7 limit value is ±7
(a) Photo couples input : Z-axis counter accumulates the Z1, Z2 phase changed by movement. This mode
includes noise immunity.
Z/1 : 1 dot per count.
Z/4 : 4 dots per count. Counted by Z1=1, Z2=1 phase, the wheel should stay at Z1=0, Z2=0 phase.
(b) Key-switches input : Pressing Z1, Z2 will start to fill the Z-axis counter with the value beginning at one.
Toggling "M" key can increase the value any time by one. The limit value is ±7.
The relationship between the value and the transmission rate as follows :
* This specification are subject to be changed without notice.
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EM84510
PS/2 SCROLLING MOUSE CONTROLLER
ValueRate per second
12.7
26.4
39.2
412.8
515
618
720
(c) Voltage-sensing mode : There are 7 voltage levels in Z1, Z2 input. The transmission table is the same as
key-switches mode. The relationship between the value of Z-axis counter and the voltage as folllows :
input current(input impedance) (500µA)
CLK, DATA postive-goingVt+0.6V
DD
-0.8V
DD
V
threshold voltage
CLK, DATA negative-goingVt -0.2V
DD
-0.4V
DD
V
threshold voltage
L,M,R,OPT,Z1,Z2 (key mode) input low voltageVail--0.3V
L,M,R,OPT,Z1,Z2 (key mode) input high voltageVaih0.7V
DD
-- V
DD
V
L,M,R,Z1,Z2 (key & voltage mode)Rmi92-310KΩ
input resistor(Vin=VDD)
OPT input resistor(Vin=V
)Rxi133-400KΩ
DD
DATA, CLK input currentIdc0.56-1.86mA
(pull up resistor)(Vin=0V )
DATA,CLK low output voltage(Iprl=-4mA)Vprl--0.4V
L,M,R,X1,X2,Y1,Y2,Z1,Z2, OPTIil0- -1.0µA
input leakage current (Vin=0V)
OPT high output currentV
(Iopt=10mA)V
=4.5V3.2--
DD
=5VIdc4.5--V
DD
=5.5V5.5--
V
DD
* This specification are subject to be changed without notice.
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PS/2 SCROLLING MOUSE CONTROLLER
* All voltages in above table are compared with VSS.
* All parameters in above table are tested under V
* CLK & DATA output gates are open drains that connect to pull up resistors.
* X1, X2,Y1,Y2 Input Impedance
DD
=5V.
EM84510
MAX.
TYP.
MIN.
16.0K
15.0K
14.0K
13.0K
12.0K
11.0K
10.0.K
9.0K
8.0K
7.0K
6.0K
5.0K
4.0K
3.0K
2.0K
1.0K
0
10.0M
1.0
2.0
VOLTS (LIN)
3.0
4.0
5.0
* This specification are subject to be changed without notice.
Mouse Sample DATA fromTmdc-13.3-us
CLK rising Edge
System CLK Active TimeTsca-40-us
System CLK Inactive TimeTsci-40-us
Time from DATA Transition to Falling Edge of CLKTsdc-13.3-us
Time from rising Edge of CLK to DATA TransitionTscd-26.7-us
Time to mouse Inhibit after the 11th CLK toTpi0-50us
ensure mouse does not start another Transmission
PS. The AC timings are measured under using 35 KHz system clock signal.
TIMING DIAGRAM
(1) Photo-couples pulse width :
X1 (Y1)
X2 (Y2)
10th
CLK
Tf
11th
CLK
Stop
Bit
(2) PS/2 Mouse
(A) Receiving DATA
CLK
DATA
Inhibit
><
Tmca
><
Tmdc
Start
Bit
Tr
1st
CLK
2nd
CLK
9th
CLK
><
Tmci
• • • • • • • • • • • •• • • • • • •
Bit0 -Bit7
Parity
Bit
•••••
Line
Control
Bit
* This specification are subject to be changed without notice.