HT6523
PS/2 Mouse Controller
Pin Assignment
Pin Description
Pin No.
Pin Name
I/O
Description
1, 5
NC
No connection
2
TEST
I
If TEST is floating or connected to VSS, then the chip is under normal opera-
tion. If TEST is connected to VDD, it will operate under the TEST mode.
3
RESET
I
Input to reset internal LSI
4
OSC
I
OSC is connected to an external resistor then to VDD to generate a 6MHz sys-
tem clock.
6
CLK
I/O
Synchronous clock signal. The mouse generates a clock signal when sending
data to and receiving data from the system.
7
DATA
I/O
Bidirectional data transmission line
8
VSS
Negative power supply, ground
9
10
11
RB
MB
LB
I
In the non-active state these 3 switch inputs are pulled low. To activate they
must be connected to VDD.
In the TEST mode, MB, LB will indicate the condition of the X1, X2 inputs, if RB
is left floating or connected to VSS. Also in the TEST mode, if RB is connected
to VDD then MB and LB will indicate the condition of the Y1 and Y2 inputs.
12
13
14
15
X1
X2
Y1
Y2
I
Mouse interface input terminal. Four photo-coupler signals denote UP, DOWN,
LEFT and RIGHT state.
16
VDD
Positive power supply
Rev. 1.20
1
March 6, 2003
General Description
The HT6523 is a PS/2 compatible mouse controller IC.
Capable of driving up to 3 key-switches and 4
photo-couplers directly into a 6-pin connector line.
Features
Compatible with IBM PS/2 mouse
Integrated oscillator circuit with external resistor
6MHz clock frequency
Minimal external components
Three key-switches and four photo-coupler inputs
Supports test mode operation
16-pin DIP package
1 6
1 5
1 4
1 3
1 2
1 1
1 0
9
1
2
3
4
5
6
7
8
H T 6 5 2 3
1 6 D I P - A
N C
T E S T
R E S E T
O S C
N C
C L K
D A T A
V S S
V D D
Y 2
Y 1
X 2
X 1
L B
M B
R B
Absolute Maximum Ratings
Supply Voltage ...........................V
SS
-0.3V to V
SS
+5.5V
Storage Temperature ............................
-50C to 125C
Input Voltage............................. VSS
-0.3 to VDD+0.3V
Operating Temperature...........................
-25C to 70C
Note: These are stress ratings only. Stresses exceeding the range specified under
Absolute Maximum Ratings may
cause substantial damage to the device. Functional operation of this device at other conditions beyond those
listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliabil-
ity.
D.C. Characteristics
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
V
DD
Conditions
V
DD
Operating Voltage
4.75
5.25
V
I
DD
Operating Current
5V
f
SYS
=6MHz, No load
5
mA
V
IL
Input Low Voltage for I/O Ports
3V
0
0.9
V
5V
0
1.5
V
IH
Input High Voltage for I/O Ports
3V
2.1
3
V
5V
3.5
5
V
IL1
Input Low Voltage (RESET)
3V
0
0.7
V
5V
0
1.3
V
IH1
Input High Voltage (RESET)
3V
2.3
3
V
5V
3.8
5
V
IL2
Input Low Voltage (X1, X2, Y1, Y2)
3V
0
1
V
5V
0
2
V
IH2
Input High Voltage (X1, X2, Y1, Y2)
3V
2
3
V
5V
3
5
I
OL
I/O Ports Sink Current
3V
V
OL
=0.3V
1.5
2.5
mA
5V
V
OL
=0.5V
4
6
I
OH
I/O Ports Source Current
3V
V
OH
=2.7V
-1
-1.5
mA
5V
V
OH
=4.5V
-2
-3
I
OL1
CLK, DATA Sink Current
3V
V
OL
=0.3V
8
mA
5V
V
OL
=0.5V
8
I
OH1
CLK, DATA Source Current
3V
V
OH
=2.7V
-1.5
-2.5
mA
5V
V
OH
=4.5V
-1.5
-2.5
R
PH
Pull-high Resistance of CLK, DATA
3V
5
7.5
10
k
W
5V
3
4.7
6.3
R
PL
Pull-low Resistance of TEST, RB,
MB, LB
3V
10
30
50
k
W
5V
8
17
35
R
PL1
Pull-low Resistance of X1, X2, Y1,
Y2
3V
60
100
160
k
W
5V
35
60
90
HT6523
Rev. 1.20
2
March 6, 2003
A.C. Characteristics
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
f
SYS
System Clock (RC OSC)
3V
R
OSC
=120K
5.4
6
6.6
MHz
5V
R
OSC
=120K
5.4
6
6.6
MHz
t
RES
External Reset Low Pulse Width
3V
1
ms
HT6523
Rev. 1.20
3
March 6, 2003
Functional Description
Power-on Reset
The Mouse logic generates a power-on reset at power
up after 600 millisecond
20%.
Modes of Operation
Reset
After power up or when receiving a reset command,
CLK and DATA lines can go to a positive level. The
mouse waits between 300 to 500 milliseconds and
sends AA to the host, followed by a device ID of 00.
After reset the mouse is set to its default values: Incre-
mental stream mode, 1:1 scaling, report rate of 100, 6
counts per mm at 320 DPI or 4 counts per mm at 200
DPI, and then disable itself. No further action occurs
until a command is sent from the host.
Stream
In this mode, a data report is transmitted to the system
if a switch is pressed or released, or if at least one
count of movement has been detected. The maximum
rate of transfer is the programmed sample rate.
Remote
In this mode, data is transmitted only in response to a
read data command.
Wrap
In this mode, any byte of data sent by the system, ex-
cept hex EC or hex FF, is returned by the mouse.
Data Transmission
During data transmission, CLK is used to clock serial
data. The mouse generates a clocking signal when
sending data to and receiving data from the system. The
system requests the mouse receiving system data out-
put by forcing the data line to an inactive level and allow-
ing CLK to go to an active level.
Communication is bidirectional using the clock and data
signal lines. The signal for each of these lines comes
from open collector devices, allowing either the mouse
or the system to force a line to an inactive level. During a
non-transmission state, CLK and DATA are both held at
an active level.
Data output
When the mouse is ready to transmit, it checks for an
inhibit signal or a host request-to-send status on CLK
and DATA. If CLK is low, data is continuously updated
in the mouse and no transmissions are made. If CLK
is high and DATA is low (request-to-send), the data is
also updated in the mouse, the mouse inputs the host
data, and no transmissions are started by the mouse
until CLK and DATA are both high. If CLK and DATA
are both high, the mouse proceeds to output 0 start
bit, 8 data bits, parity bit, and stop bit if a transmission
is required. Data is valid prior to the falling edge of
CLK and beyond the rising edge of CLK. During trans-
mission, the mouse checks for a line contention by
checking for an inactive level on CLK at intervals not
to exceed 100
ms. Contention occurs when the host
lowers CLK to inhibit the mouse output after the
mouse starts a transmission. If this occurs before the
rising edge of the tenth clock (parity bit), the mouse in-
ternally stores its data packet in the mouse buffer and
returns both DATA and CLK high. If there is no con-
tention by the tenth clock, the mouse completes the
transmission. Following a transmission, the host can
inhibit the mouse until it services the input or until it re-
quests to send a response if necessary.
Data input
When the host is ready to send data to the mouse, it
first checks to see if the mouse is transmitting data. If
the mouse is transmitting, the host can override the
mouse output by forcing CLK low before the tenth
clock. If the mouse transmits beyond this, the host re-
ceives the data. If the mouse is not transmitting or if
the host overrides the mouse output, the host forces
CLK to an inactive level for a period of not less than
100
ms while preparing for output. When the system is
ready to output 0 start bit (data line is low), it allows
CLK to go to an active level. The mouse checks this
state every 10ms.
If request-to-send is detected, the mouse clocks 11
bits. After the tenth clock, the mouse checks for a high
on the DATA line and if found, the mouse forces DATA
to a low level and clocks once more. This signals the
host to return to the ready state when it can accept in-
put or go to an inhibit mode until ready. If DATA is
found at an inactive level following clock 10, a framing
error has occurred and the mouse continues to clock
until DATA is high, then clocks the line control bit and
request a resend. For host commands and data trans-
mission that requires a response, the host waits for
the mouse to respond before sending its next output.
The following describe valid commands:
Hex Code
Command
Description
FF
Reset
This command cause the mouse to enter a reset mode and do an internal self-test.
FE
Resend
The system can send this command when it detects an error in any transmission
from the mouse. The Resend command could be sent following a mouse transmis-
sion and before the system enables the interface allowing the next mouse output.
On receipt of Resend, the mouse retransmits the previous three bytes if the previ-
ous output was a 3-byte packet. The previous two bytes if the previous output was a
2-byte packet, and the previous one byte if the previous output was a 1-byte packet,
unless the previous output from the mouse was a Resent command. In this case,
the mouse will resend the previous output prior to the Resend command. If a Re-
send command is received by the mouse from the host immediately following a
3-byte data packet transmission from the mouse to the host while the mouse is in
stream mode. The mouse should resend the 3-byte data packet prior to clearing the
count accumulators.
F6
Set default
This command reinitializes all conditions to the power-on default state.
F5
Disable
This command is used in the stream mode to stop transmissions initiated from the
mouse. It responds to all other commands while disabled. If the mouse is in the
stream mode, it must be disabled before sending it any command that requires a
response.
F4
Enable
Begin transmission, if in stream mode
F3, XX
Set sampling
rate
In the stream mode, this command sets the sampling rate to the value indicated by
bytes hex XX shown in the following figure:
Second Byte hex XX (sample rate): hex 0A (10/sec), hex 14 (20/sec),
hex 28 (40/sec), hex 3C (60/sec), hex 50 (80/sec), hex 64 (100/sec),
hex C8 (200/sec)
F2
Read device type
This command always receives a response of hex 00
HT6523
Rev. 1.20
4
March 6, 2003
The response must be within 20ms, unless the host
inhibits the mouse output or inhibits the data transmis-
sions from the system that require a response. If the
host initiates a command or data transmission and the
response is invalid or has a parity error, the host re-
transmits the command or data. If after two retries the
response is still invalid or has a parity error, the host
resets the mouse.
Data Format
The following data report format is valid for the stream
and remote modes and is 3 bytes long:
Byte
Bit
Description
3
2
1
7
6-1
0
7
6-1
0
7
6
5
4
3
2
1
0
MSB of Y Data
Y Data
LSB of Y Data
MSB of X Data
X Data
LSB of X Data
Y Data Overflow 1=Overflow
X Data Overflow 1=Overflow
Y Data sign 1=Negative
X Data sign 1=Negative
Reserved always=1
Reserved for middle Button
Right Button Status 1=Pressed
Left Button Status 1=Pressed
Commands
The following table lists all the valid commands:
Hex Code
Command
FF
FE
F6
F5
F4
F3
F2
F0
EE
EC
EB
EA
E9
E8
E7
E6
Reset
Resend
Set default
Disable
Enable
Set sampling rate
Read device type
Set remote mode
Set wrap mode
Reset wrap mode
Read data
Set stream mode
Status request
Set resolution
Set scaling 2:1
Reset scaling
Hex Code
Command
Description
F0
Set remote mode
This command sets the remote mode. Data values are reported only in response to
a Read Data command.
EE
Set wrap mode
This command sets the wrap mode. This mode remains until hex FF or hex EC is
received.
EC
Reset wrap mode
This command resets the wrap mode
EB
Read data
This command requests that all data defined in the data packet format be transmit-
ted. This command is executed in either remote or stream mode. The data is trans-
mitted even if there has been no movement since the last report or the switch status
is unchanged. Following a Read Data command, the accumulators are cleared af-
ter a data transmission.
EA
Set stream mode
This command sets the stream mode
E9
Status request
When this command is issued by the system, the mouse responds with a 3-byte
status report as follows:
E8, XX
Set resolution
The mouse provides four resolutions selected by the second byte of this command
as follows:
E7
Set scaling 2:1
Scaling is used to provide a course/fine tracking response. At the end of a sample
interval in the stream mode, the current X and Y data values are converted to new
values. The sign bits are not involved in this conversion. 2:1 scaling is only per-
formed in stream mode. In response to a Read Data command, the mouse will
transmit the current value before conversion.
E6
Reset scaling
This command restores 1:1 scaling
HT6523
Rev. 1.20
5
March 6, 2003
Byte
Bit
Description
3
2
1
0~7
0~7
7
6
5
4
3
2
1
0
Current sampling rate
Current resolution setting
always = 0
0 = Stream mode, 1 = Remote mode
0 = Disabled, 1 = Enabled
0 = Scaling 1:1, 1 = Scaling 2:1
always = 0
1 = Left button pressed
Reserved for middle button
1 = Right button pressed
Second Byte
Resolution (Counts per mm)
hex XX
200 DPI
320 DPI
400 DPI
hex 00
hex 01
hex 02
hex 03
1
2
4
8
1
3
6
12
2
4
8
16
Input
Output
0
1
2
3
4
5
N (
6)
0
1
1
3
6
9
2.0
N
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