Holtek Semiconductor Inc HT82K28A Datasheet

Win98 Keyboard Encoder

Features

Designed for Windows 95/98/NT

·

Supports 3 Windows 95 Keys

·

Supports Power, Sleep and Wake-up Win

·

dows 98 ACPI functions Supports Japanese, Korean and Portuguese

·

Supports Japanese DOS/V 106-key

·

keyboard Supports code set 1, for PS/2 model

·

30 keyboard

General Description

The HT82K28A is a keyboard encoder espe cially designed for IBM PC/AT, IBM PS/2 and all compatible machines.

The HT82K28A accepts keyboard inputs and contains a 16-character first-in-first-out buffer

Pin Assignment

HT82K28A

Supports code set 2, for PC/AT, PS/2 model

·

50,60 keyboards Supports code set 3, for PS/2 model

·

80 keyboard RC oscillator

·

Phantom key detection

·

Minimal external components

·

Pin-compatible with Holtek HT6547E-2

·

40-pin DIP/DICE form

·

in which data is stored. An inexpensive RC os

-

cillator can be used for the system clock. The device offers the advantage of simple imple mentation in high performance and low cost keyboard applications.

-

OSC1

VSS

VDD

VSS

IO 0

IO 1

C2

C3

C4

C5

C6

C7

R10

R11

R12

R0

R1

R2

R3

R4

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

H T82K 28A

4 0 D IP

C1

C0

DATA

CLOCK

R18

R17

NC

R16

CAP

NUM

SCRL

R9

R8

R15

R14

NC

R13

R7

R6

R5

1 February 16, 2000

HT82K28A

Pin Description

Pin No. Pin Name I/O Description

1 OSC1 I System clock input

2, 4 VSS

3 VDD

5, 6 IO0~IO1 O Customer defined optional output lines

39, 40, 7~12

16~23, 28, 29, 13~15 24, 26, 27 33, 35

25, 34 NC

30 SCRL O LED pin

31 NUM O LED pin

32 CAP O LED pin

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

38 DATA I/O Bidirectional data transmission line

C0~C7 I Keyboard matrix scanning input pins

R0~R18 O Keyboard matrix scanning output pins

Negative power supply, ground

¾

Positive power supply

¾

No connection

¾

Absolute Maximum Ratings

Supply Voltage ............................4.75V to 5.25V

Storage Temperature.................-55°Cto125°C

Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maxi-

mum 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.

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

Operating Temperature ..................0°Cto70°C

2 February 16, 2000

-0.3V to VDD+0.3V

SS

HT82K28A

Electrical Characteristics

Ta=25°C

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

I

V

R

f

DD

IL

IH

OL

ph

SYS

Operating Voltage

Operating Current

Input Low Voltage (C0~C7)

Input Low Voltage (DATA, CLOCK)

Input High Voltage

Output Low Voltage (R0~R18)

Output Low Voltage (DATA, CLOCK)

Internal Pull-high Resistance (C0~C7)

Internal Pull-high Resistance (CLOCK, DATA)

System Clock

I

OL

I

OL

¾

4.75 5 5.25 V

¾¾

¾

=10mA

=15mA

¾

0

3.5

¾¾

51020

2515

¾¾4¾

25mA

0.6 V

¾

0.6 V

¾

V

¾

DD

0.5 V

kW

MHz

V

3 February 16, 2000

Functional Description

The HT82K28A basic function is to detect key press and release activity and to transmit the corresponding scan code, as well as make and break codes to the system.

The device also accepts commands from the sys tem and responds to the system if necessary. All communication between the keyboard and the system is managed through the CLOCK and DATA pins.

The keyboard begins to scan for pressed or re leased keys and commands from the system after the BAT (Basic Assurance Test) has been run.

Working modes

Three working modes are supported by the HT82K28A. These are setup by the alternate scan code command F0. The various modes are described as follows.

Mode 3

·

Supports code set 3, for PS/2 model 80 key boards.

·

-

Enters mode 3 when an F0 command is issued followed by a 3".

·

Contains an 11 bit data stream, including one start bit (always zero) eight data bits, one par ity bit (odd parity) and one stop bit (always one).

-

Buffers

The buffers support the following functions:

·

16-byte FIFO buffer: stores 16 keystrokes scan codes.

·

Additional keystrokes will be ignored.

·

Response codes, i.e FA/FE... do not occupy buffer positions.

HT82K28A

-

Mode 1

·

Supports code set 1 for PS/2 model 30 key boards.

·

Enters mode1 after an F0 Command is issued followed by a 1".

·

Contains an 11 bit data stream, including one start bit (always zero) eight data bits, one parity bit (odd parity) and one stop bit (always one).

·

All keys are typematic/make/break as default.

·

The working mode can be changed again in this mode, by issuing an F0 command followed by an option. See the F0 command for more detail.

Mode 2

·

Supports code set 2 for PC/AT, PS/2 model 50, 60 keyboards.

·

Enters mode 2 after power on. The working mode can be changed by an F0 command followed by an option byte 1, 2 or 3. See the F0 command for more details.

·

Contains an 11 bit data stream, including one start bit (always zero) eight data bits, one par ity bit (odd parity) and one stop bit (always one)

·

All keys are typematic/make/break as default.

Basic assurance test - BAT

The following functions are offered by the Basic

-

Assurance Test:

·

Turns on LED status indicators.

·

Keyboard processor test.

·

RAM test.

·

Turns off LED status indicators, i.e. the LEDs.

·

Reports the BAT result to the system.

Note: During the BAT, activity on the "clock"

and "data" line are ignored. The LED¢s are turned on at the beginning and turned off at the end of the BAT. The BAT takes a minimum of 450ms after POR and a maximum of 2.5s. The re sponse to a satisfactory BAT completion is ²AA² and response to BAT failure is an ²FC² error. The reset keyboard com mand ²FF² will also cause the keyboard to execute the BAT. Completion codes are sent between 300 and 500ms after a

-

reset command is acknowledged. After the BAT, the keyboard sets the keys to typematic and make/break, and sets the default typematic rate and delay.

-

4 February 16, 2000

HT82K28A

Power-on

Twoimportant activities take place when power is first applied to the keyboard. The first is the presence of an H/W signal POR (Power-On-Re set) that resets the keyboard processor. The sec ond activity is the running of the self test BAT (Basic Assurance Test) routine.

PO R R eset

150m s~2s 300m s~500m s

450m s~2.5sec

Pow er on start BA T started BAT com plete

PC-type/mode/code set

The following table describes the relationship between different computer types, the working mode and the code sets.

PS/2 30 mode 1 code set 1

PC-AT mode 2 code set 2 PS/2 50 mode 2 code set 2 PS/2 60 mode 2 code set 2 PS/2 80 mode 3 code set 3

The mode can be changed between mode 2 & 3.

Keys

·

For code set 1, 2 All keys except the PAUSE key have a make

and break code. The PAUSE key has a make code only.

The defaults except for PAUSE are make/ break/typematic. In mode 1, 2 and 3 the key type may be changed to be one of the follow ing:

m ode1

All keys except PAUSE are typematic. Typematic means that the KB keeps send

-

ing make codes if the key is held down.

-

The data report is according to the typematic rate/delay: Default values are: delay 500ms ± 20%

10.9 char/sec ± 20%

The typematic rate and delay can be modi

-

fied with the F3 command.

¨

If two or more keys are held down, only the last key pressed repeats at the typematic rate.

Typematic operation stops when the last key pressed is released even if other keys are still held down.

If a key is pressed and held down while key

board transmission is inhibited, only the first make code is stored in the buffer over

flow as a result of typematic action.

Four key types are supported as shown:

Key type press hold release

Typematic Make/break Make Typematic/

make1 make1 make1 make1

make2

X X

make2

X

break

X

break

make/break

Note: "make1" send out only one make code.

"Make2" continue sending out make

codes until key is released.

"X" nothing sent out.

·

For code set 3

¨

-

Typematic

¨

Make/break

¨

Make

¨

Typematic/make/break

Can be configured by command

m ode2 m ode3

¨

Typematic

¨

Make/break

¨

Make

¨

Typematic/make/break

Time interval between phantoms

The time interval between two continuous error codes 00/FF sent while phantom detected= 1000ms ± 20%

5 February 16, 2000

System command table

Command mode 1 mode 2 mode 3

FF - reset FE - resend FD - set key type make FC - set key type make/break FB - set key type typematic FA - set all keys typematic/make/break F9 - set all keys make F8 - set all keys make/break F7 - set all keys typematic F6 - set default F5 - default disabled F4 - enable F3 - set typematic rate/delay F2 - Read ID F1 F0 - select alternate scan codes EF EE - Echo ED - set/reset status indicators

HT82K28A

y y y y y y y y y y y y y y x y x y y

The keyboard should respond within 20ms, ex cept when performing the BAT or executing a reset command.

Command description

·

Default disable - F5

¨

Send an acknowledge FA to the system

¨

Clear its output buffer, FIFO

¨

Set the default key types

¨

Set typematic rate/delay as default value

¨

Clear the last typematic key

¨

Stop scanning and wait for further instruc tion

·

Echo - EE

¨

Send an EE to the system

¨

Continue scanning if the keyboard is en abled

Note: This command does not need to feed

back the ACK

·

-

Enable - F4

¨

Send an ACK to the system

¨

Clear output buffer

¨

Clear the last typematic key

¨

Start scanning

·

Invalid command

¨

Send an FE to the system

¨

No further activities Note: No ACK

·

Read ID - F2

-

¨

Send an ACK to the system

¨

Discontinue scanning

¨

2 byte ID-AB, 83 The 2nd byte must follow the completion of

-

the first byte within 500ms

¨

Resume scanning

6 February 16, 2000

Holtek Semiconductor Inc HT82K28A Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual

Features

General Description

Pin Assignment

Pin Description

Absolute Maximum Ratings

Electrical Characteristics

Functional Description