HOLTEK HT82K628A User Manual

Windows 2000 PS/2 Keyboard Encoder

Features

·

Design for Windows 95/98/NT/2000/XP

·

Supports WindowsTMkeys

·

Supports PC/AT and PS/2 code set 1, 2, 3

·

Supports Japanese , Korean , Brazilian and
European

·

RC oscillator

·

Phantom key detection

·

Low power consumption

General Description

The HT82K628A is a keyboard encoder designed for
IBM PC/AT, IBM PS/2 and all compatible machines.

The HT82K628A accepts keyboard inputs and provides
a 16-character first-in-first-out buffer in which data is
stored.

Pin Assignment

HT82K628A

·

101/102/104/105/107/109 keys or other special ap
plication keyboard encoder

·

8 external hot keys

·

Supports Mini-keyboard and Internet/Multimedia
keyboard

·

WINDOWS is a registered trademark of Microsoft
corporation

·

40-pin DIP package

An inexpensiveRC oscillator can beused for the system
clock. Simple implementation of this device is an advan
tage for high performance and low cost keyboard appli
cations.

-

-

-

R 5

R 4

C 3

C 2

C 1

C 0

R 3

R 2

R 1

R 0

R 1 9

R 1 8

R 1 7

R 1 6

V S S

S C R O L L

N U M

D A T A

C L O C K

F n S e l e c t

1

2

3

4

5

6

7

8

9

1 0

1 1

1 2

1 3

1 4

1 5

1 6

1 7

1 8

1 9

2 0

4 0

3 9

3 8

3 7

3 6

3 5

3 4

3 3

3 2

3 1

3 0

2 9

2 8

2 7

2 6

2 5

2 4

2 3

2 2

2 1

H T 8 2 K 6 2 8 A

4 0 D I P - A

R 6

R 7

C 4

C 5

C 6

C 7

N C

O S C 1

V D D

R E S E T

C A P S

R 8

R 9

R 1 0

R 1 1

R 1 2

R 1 3

R 1 4

R 1 5

M a c r o K e y s e l e c t

Rev. 1.60 1 April 16, 2004

HT82K628A

Pin Description

Pin No. Pin Name I/O Description

10~7, 2~1,
40~39, 29~22,
14~11

6~3, 38~35 C0~C7 I Keyboard matrix scanning input pins

15 VSS

16 SCROLL O Scroll Lock indicator

17 NUM O Num Lock indicator

18 DATA I/O Bidirectional data transmission line

19 CLOCK I/O Synchronous clock signal. Used to clock the transmission data.

20 Fn Select I Mini-keyboard select, enables the function if connected to VSS.

21 Macro Key Select I Macro Key select, disables the function if connected to VSS.

30 CAPS O Caps Lock indicator

31 RESET

32 VDD

33 OSC1 I

34 NC

R0~R19 O

Keyboard matrix scanning output pins

¾

Negative power supply, ground

Chip reset input. Active low. Built-in power-on reset circuit to reset the en

I

tire chip. Chip can also be externally reset via RESET

5.0V positive power supply

¾

pin.

System clock input; 58.3kW resistor connected for RC OSC

No connection

¾

-

Absolute Maximum Ratings

Supply Voltage ..........................VSS-0.3V to VSS+5.5V

Input Voltage .............................V

3V to VDD+0.3V

SS-0.

Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maximum Ratings² 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 reliabil­ity.

Electrical Characteristics

Symbol Parameter

V

I

V

V

I

I

I

I

R

R

R

f

DD

DD

IL

IH

OL

OH1

OH2

LED

ph

ph1

ph2

SYS

Operating Voltage

Operating Current (RC OSC) 5V

Input Low Voltage 5V

Input High Voltage 5V

Sink Current (C0~C7, R0~R19, DATA, CLOCK) 5V

Source Current (C0~C7, R0~R19) 5V

Source Current (Scroll, Num, Caps) 5V

LED Sink Current (Scroll, Num, Caps) 5V VOL=3.4V 10 18 24 mA

Internal Pull-high Resistance (C0~C7, R0~R19) 5V

Internal Pull-high Resistance (DATA, CLOCK) 5V

Internal Pull-high Resistance (RESET)5V

System Clock (RC OSC) 5V

Storage Temperature ...........................-50°Cto125°C

Operating Temperature ..........................-25°Cto70°C

Ta=25°C

Test Conditions

V

DD

Conditions

¾¾

No load, f

SYS

= 4MHz

¾
¾

= 0.5V

V

OL

= 4.5V

V

OH

= 4.5V

V

OH

¾
¾
¾
¾¾4¾

Min. Typ. Max. Unit

3 5 5.25 V

2.5 5 mA

¾

0

3.5

16 25

-8 -16 ¾

-2.5 -4 ¾

51220

2 4.7 8

25 50 75

¾
¾

1.5 V

5V

mA

¾

mA

mA

kW
kW
kW

MHz

Rev. 1.60 2 April 16, 2004

Functional Description

Command from the Host

The following table shows the commands that the host
may send and their hexadecimal values.

Command Hex Value

Set/Reset Status Indicators ED

Echo EE

Invalid Command EF

Select Alternate Scan Codes F0

Invalid Command F1

Read ID F2

Set Typematic Rate/Delay F3

Enable F4

Default Disable F5

Set Default F6

Set All Keys - Typematic F7

Set All Keys - Make/Break F8

Set All Keys - Make F9

Set All Keys - Typematic/Make/Break FA

Set Key Type - Typematic FB

Set Key Type - Make/Break FC

Set Key Type - Make FD

Resend FE

Reset FF

The commands may be sent to the HT82K628A at any
time and the HT82K628A will respond within 25ms ex­cept whenperforming the internal diagnostics or execut
ing a Reset command.

EDH - Set/Reset Status Indicators

Three status indicators on the keyboard-Num Lock,
Caps Lock, and Scroll Lock-are accessible by the host.
The HT82K628A activates or deactivates these indica
tors when it receives a valid command-code sequence
from the system. The command sequence begins with
the command byte (hex ED). The HT82K628A responds
to the command byte with ACK, discontinues scanning,
assignments for this option byte are as follow:

Bit Indicator

0 Scroll Lock Indicator

1 Num Lock Indicator

2 Caps Lock Indicator

3~7 Reserved (Must be 0)

If a bit for an indicator is set to 1, the indicator is turned
on. If a bit is set to 0, the indicator is turned off.

HT82K628A

The HT82K628A responds to the option byte with ACK,
sets theindicators and if the HT82K628Awas previously
enabled, continues scanning. The status of the indica
tors will reflect the bits in the option byte and can be acti
vated or deactivated in any combination. If another
command is received in place of the option byte, execu
tion of the Set/Reset Mode Indicators command is
stopped, with no change to the indicator status, and the
new command is processed.

Immediately after power-on, the lights default to the off
state. If the Set Default and Default Disable commands
are received, the lamps remain in the state they were in
before the command was received.

EEH - Echo

Echo is a diagnostic aid. When the HT82K628A re
ceives this command, it issues a hex EE response and if
the HT82K628A was previously enabled, continues
scanning.

EFH and F1H - Invalid Command

EFh and F1h are invalid commands and are not sup
ported. If HT82K628A receives one of these and sends
it, the HT82K628A will not acknowledge the command,
but returns a Resend command and continues in its pre­vious scanning state.

F0H - Select Alternate Scan Codes

This commandinstructs the HT82K628A to select one of
the three sets of scan codes. The HT82K628A acknowl­edges receipt of this command with ACK, clears both
the output buffer and the typematic key. The host then
sends the option byte and the keyboard responds with

­another ACK. An option byte value of hex 01 selects

scan code set 1, hex 02 selects set 2 and hex 03 selects
code set3.

An option byte value of hex 00 causes the HT82K628A
to acknowledge with ACK and sends a byte telling the
host which scan code set is currently in use.

­After establishing the new scan code set, the
HT82K628A returns to the scanning state it was in be
fore receiving the Select Alternate Scan Codes com
mand.

F2H - Read ID

This command requests identification information from

the HT82K628A. The HT82K628A responds with ACK,
discontinues scanning and sends the two keyboard ID
bytes hex83h and Abh. After the output of the second ID
byte, the HT82K628A resumes scanning.

-

-

-

-

-

-

-

Rev. 1.60 3 April 16, 2004

HT82K628A

F3H - Set Typematic Rate/Delay

The host issues the Set Typematic Rate/Delay com
mand to change the typematic rate and delay. The
HT82K628A responds to the command with ACK, stops
scanning and waits for the system to issue the rate/de
lay value byte. The HT82K628A responds to the value
byte with another ACK, sets the rate and delay to the
value indicated, and continues scanning (if it was previ
ously enabled). Bit6 and 5 indicate the delay, and bits 4,
3, 2,1 and 0 indicate the rate. Bit7 is always 0. The delay
is equal to 1 plus the binary value bit 6 and 5, multiplied
by 250ms±20%.

The period (interval from one typematic output to the
next) is determined by the following equation:

Period = (8+A)*(2^B)*0.00417 seconds.

Where:

A = binary value of bits 2, 1, and 0.

B = binary value of bits 4, and 3.

The typematic rate is 1 for each period and are listed as
follows:

Bit

00000 30.0 10000 7.5

00001 26.7 10001 6.7

00010 24.0 10010 6.0

00011 21.8 10011 5.5

00100 20.0 10100 5.0

00101 18.5 10101 4.6

00110 17.1 10110 4.3

00111 16.0 10111 4.0

01000 15.0 11000 3.7

01001 13.3 11001 3.3

01010 12.0 11010 3.0

01011 10.9 11011 2.7

01100 10.0 11100 2.5

01101 9.2 11101 2.3

01110 8.0 11110 2.1

01111 8.0 11111 2.0

The default values for the HT82K628A are as follows:
Typematic rate= 10.9 characters per second ± 20%
Delay = 500ms±20%

The execution of this command stops without change to
the existing rate if another command is received instead
of the rate/delay value byte.

Typematic

Rate ± 20%

Bit

Typematic

Rate ± 20%

F4H - Enable

Upon receipt of this command, the HT82K628A will re

­spond with ACK, clears its output buffer, clears the last

typematic key, and starts scanning.

-

F5H - Default Disable

The Default Disable command resets all conditions to
the power on default states. The HT82K628A will re

­spond with ACK, clears its output buffer, sets the default
key types (scan code set 3 operation only) and
typematic rate/delay, and clears the last typematic key.
The HT82K628Athen stops scanning and awaits further
command.

F6H - Set Default

The Set Default command resets all conditions to the
power on default states. The HT82K628A will respond
with ACK, clears its output buffer, sets the default key
types (scan code set 3 operation only) and typematic
rate/delay, and clears thelast typematic key then contin
ues scanning.

F7H, F8H, F9H, FAH - Set All Keys

These commands instruct the HT82K628A to set all
keys to the type listed below:

Hex Value Command

F7 Set All Keys-Typematic

F8 Set All Keys-Make/Break

F9 Set All Keys-Make

FA Set All Keys-Typematic/Make/Break

The HT82K628Awill respond withACK, clears its output
buffer, sets all keys to the type indicated by this com­mand, and continues scanning (if it was previously en­abled). Although these commands can be sent using
any code set, they affect only scan codeset 3 operation.

FBH, FCH, FDH - Set Key Type

These commands instruct the HT82K628A to set indi
vidual keys to the type listed below:

Hex Value Command

FB Set Key Type-Typematic

FC Set Key Type-Make/Break

FD Set Key Type-Make

The HT82K628Awill respond withACK, clears its output
buffer and prepares to receive key identification. Key
identification is accomplished by the host identifying
each key by its scan code value as defined in scan code
set 3. Only scan code set 3 values are valid for key iden
tification. The type of each identified key is set to the
value indicated by the command. Although these com
mands can be sent using any code set, they affect only
scan code set 3 operation.

-

-

-

-

-

-

Rev. 1.60 4 April 16, 2004

HT82K628A

FEH - Resend

The hostsends this command when it detects an error in
any transmissionfrom the HT82K628A. Itis sent only af
ter a data transmission and before the host allows the
next data output. When a Resend is received, the
HT82K628A sends the previous output again (unless
the previous output was Resend, in which case the
HT82K628A sends the last byte before the Resend
command).

Commands to the Host

The following table shows the commands that the
HT82K628A may send to the host, and their hexadeci

mal values.

Command Hex Value

Key Detection Error/Overrun 00 (Code Set 2 and 3)

Keyboard ID 83AB

Bat Completion Code AA

Bat Failure Core FC

Echo EE

Acknowledge FA

Resend FE

Key Detection Error/Overrun FF (Code Set 1)

00H or FFH - Key Detection Error

The HT82K628Asends a key detectionerror character if
conditions in the keyboard make it impossible to identify
a switch closure. If the HT82K628A is using scan code
set 1, the code is FFH. Forsets 2 and 3, thecode is 00H.

00H or FFH - Overrun

An overrun character is placed in the HT82K628A buffer
and replaces the last code when the buffer capacity has
been exceeded. The code is sent to the host when it
reaches the top of the buffer queue. If the HT82K628A is
using scancode set 1, the code is FFH. For sets 2 and 3,
the code is 00H.

83AbH - Keyboard ID

The keyboard ID consists of 2 bytes, Hex 83AbH. The
HT82K628A responds to the Read ID with ACK, discon
tinues scanning and sends 2 ID bytes. The low byte is
sent first followed by the high byte. Following the output
of Keyboard ID, the HT82K628A begins scanning.

EEH - Echo

The HT82K628A sends this code in response to an
Echo command.

AAH - BAT Completion Code

Following satisfactory completion of the BAT, the
HT82K628A sends AAH. Any other code indicates key

­board failure.

FCH - BAT Failure Code

If a BAT failure occurs, the HT82K628Asends this code,
discontinues scanning and waits for a host response or
reset.

FEH - Resend

The HT82K628A issues a Resend command following

­receipt of an invalid input or any input with incorrect par

ity. If the host sends nothing to the HT82K628A, no re
sponse is required.

Data Communications

·

Data output

¨

If CLK=0, no transmission (keyboard is inhibited).

¨

If CLK=1, DATA=0, no transmission (system re
quest to send).

¨

If CLK=1, DATA=1, transmission permitted.

¨

Data will be valid before the trailing edge and be
yond the leading edge of the clock.

¨

The KB checks the clock line for an active level of at
least every 60ms.

¨

If line contention occurs (system brings the clock
low before the tenth clock), set clock=data=high.

·

Data input

¨

The system overrides the clock line for at least
60ms.

¨

The keyboard checks the clock line state at inter­vals of 10ms

¨

If a system request-to-send is detected, the key­board counts 11 data bits.

¨

Data will be valid before the rising edge and beyond
the falling edge

¨

After the 10th bit, the keyboard checks for an active
level onthe ²data² line. If the line is active it isforced
to be inactive, and counts one more bit.

Note: This action signals the system that the

keyboard has received its data. Upon

reception of this signal, the system returns

to the ready state, in which it can accept

-

keyboard outputs or goes to the inhibit
state until it is ready.

If the keyboard ²data² line is found to be at an inactive
level followingthe 10th bit, a frame errorhas occurred,
and the keyboard continues to count until the ²data²
line becomes active. The keyboard then makes the
²data² line inactive and sends a Resend.

-

-

-

-

-

Rev. 1.60 5 April 16, 2004

HT82K628A

Data Stream

Mode 1,2,3

B1:

B2:
b3:
b4:
b5:

B6
b7:
b8:
b9:

b10:

b11:

Note:

The parity bit is either 1 or 0, and the 8 data bits, plus the parity bit, always have an odd number of 1ms.

Key Code Set 1

Key Number

and Symbol

1 ~ ' 29/A9 47 X 2D/AD

2 ! 1 02/82 48 C 2E/AE

3 @ 2 03/83 49 V 2F/AF

4 # 3 04/84 50 B 30/B0

5 $ 4 05/85 51 N 31/B1

6 % 5 06/86 52 M 32/B2

7 ^ 6 07/87 53 < , 33/B3

8 & 7 08/88 54 > . 34/B4

9 * 8 09/89 55 ? / 35/B5

10 ( 9 0A/8A 57 Shift (R) 36/B6

11 ) 0 0B/8B 58 Ctrl (L) 1D/9D

12 _ - 0C/8C 60 Alt (L) 38/B8

13 + = 0D/8D 61 Space 39/B9

14 56 7D/D6 FD 62 Alt (R) E0 38/E0 B8

15 Back Space 0E/8E 64 Ctrl (R) E0 1D/E0 9D

16 Tab 0F/8F 90 Num Lock 45/C5

17 Q 10/90 91 7 Home 47/C7

18 W 11/91 92 4

19 E 12/92 93 1 End 4F/CF

20 R 13/93 96 8

21 T 14/94 97 5 4C/CC

22 Y 15/95 98 2

23 U 16/96 99 0 Ins 52/D2

24 I 17/97 100 * 37/B7

25 O 18/98 101 9 PgUp 49/C9

26 P 19/99 102 6

27 { [ 1A/9A 103 3 PgDn 51/D1

28 } ] 1B/9B 104 . Del 53/D3

*29

½

\ 2B/AB 105 - 4A/CA

Make/Break Code

Key Number
and Symbol

start bit

always 0
data bit 0
data bit 1
data bit 2
data bit 3
data bit 4
data bit 5
data bit 6
data bit 7

parity bit
(odd par)

stop bit

always 1

Make/Break Code

¬



¯

®

4B/CB

48/C8

50/D0

4D/CD

Rev. 1.60 6 April 16, 2004