Holtek Semiconductor Inc HT82K628A Datasheet

HT82K628A

Preliminary

Windows 2000 Keyboard Encoder

Features

Design for Windows 95/98/2000/NT

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 de signed for IBM PC/AT, IBM PS/2 and all com patible machines.

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

101/102/104/109 keys or other special

application keyboard encoder 8 external hot keys

Supports Mini-keyboard and Internet/Mul

timedia keyboard WINDOWS is a registered trademark of

Microsoft corporation 40-pin DIP/DICE form package

An inexpensive RC oscillator can be used for

the system clock. Simple implementation of

this device is an advantage for high perfor mance and low cost keyboard applications.

1 July 20, 2000

Pin Assignment

Preliminary

HT82K628A

R19

R18

R17

R16

VSS

SCR OLL

NUM

DATA

CLOCK

Fn Select

OSC1

VDD

RESET

CAPS

R10

R11

R12

R13

R14

R15

M a cro K ey select

H T 82K 628A

4 0 D IP

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

20 Fn Select I

21 Macro Key Select I

30 CAPS O Caps Lock indicator

R0~R19 O

Keyboard matrix scanning output pins

Negative power supply, ground

Synchronous clock signal. Used to clock the transmis sion data.

Mini-keyboard select, enables the function if connected to VSS.

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

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Preliminary

Pin No. Pin Name I/O Description

Chip reset input. Active low. Built-in power-on reset

31 RESET

32 VDD

33 OSC1 I

34 NC

Absolute Maximum Ratings

circuit to reset the entire chip. Chip can also be exter nally reset via RESET

5.0V positive power supply

pin.

System clock input; 110kW resistor connected for RC OSC

No connection

HT82K628A

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

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

3V to VDD+0.3V

SS-0.

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

Operating Temperature .............-25°Cto70°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 expo sure to extreme conditions may affect device reliability.

Electrical Characteristics

Symbol Parameter

LED

Operating Voltage

Operating Current (RC OSC)

Input Low Voltage 5V

Input High Voltage 5V

Sink Current 5V

Source Current 5V

LED Sink Current (Scroll, Num, Caps)

Test Conditions

Conditions

¾¾

No load, f

SYS

= 2MHz

¾ ¾

= 0.5V

= 4.5V

=3.2V

Min. Typ. Max. Unit

4 5 5.5 V

3.5

25mA

¾ ¾

712

-2.5 -4.5 ¾

10 14 18 mA

Ta=25°C

1.5 V

Internal Pull-high

Resistance

51220

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

ph1

Resistance

2 4.7 8

(DATA, CLOCK)

ph2

SYS

Internal Pull-high Resistance (RESET

)

System Clock (RC OSC) 5V

25 50 75

¾¾2¾

MHz

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Preliminary

Functional Description

Command from the host

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

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

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 when performing the inter nal diagnostics or executing a Reset command.

HT82K628A

byte (hex ED). The HT82K628A responds to the command byte with ACK, discontinues scan ning, 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.

The HT82K628A responds to the option byte with ACK, sets the indicators and if the HT82K628A was previously enabled, continues scanning. The status of the indicators will re flect 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 op tion byte, execution of the Set/Reset Mode Indi cators 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 receives this command, it issues a hex EE re sponse and if the HT82K628A was previously

enabled, continues scanning.

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 deac tivates these indicators when it receives a valid command-code sequence from the system. The command sequence begins with the command

EFH and F1H - Invalid command

EFh and F1h are invalid commands and are not supported. If HT82K628A receives one of these and sends it, the HT82K628Awill not acknowl

edge the command, but returns a Resend com

mand and continues in its previous scanning state.

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Preliminary

HT82K628A

F0H - Select alternate scan codes

This command instructs the HT82K628A to se lect one of the three sets of scan codes. The HT82K628A acknowledges receipt of this com mand with ACK, clears both the output buffer and the typematic key. The host then sends the option byte and the keyboard responds with an other ACK. An option byte value of hex 01 se lects 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 before receiving the Select Alternate Scan Codes command.

F2H - Read ID

This command requests identification informa tion from the HT82K628A. The HT82K628A re

sponds with ACK, discontinues scanning and sends the two keyboard ID bytes hex 83h and Abh. After the output of the second ID byte, the HT82K628A resumes scanning.

F3H - Set typematic Rate/Delay

The host issues the Set Typematic Rate/Delay command 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/delay 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 previously 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.

F4H - Enable

Upon receipt of this command, the HT82K628A will respond with ACK, clears its output buffer, clears the last typematic key, and starts scan ning.

Typematic Rate ± 20%

Bit

Typematic Rate ± 20%

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Preliminary

HT82K628A

F5H - Default disable

The Default Disable command resets all condi tions 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 the last typematic key. The HT82K628A then 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 oper ation only) and typematic rate/delay, and clears the last typematic key then continues 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

The HT82K628A will respond with ACK, 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 code set 3 operation.

Set All Keys-Typematic /Make/Break

FBH, FCH, FDH - Set key type

These commands instruct the HT82K628A to

set individual 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 HT82K628A will respond with ACK, clears its output buffer and prepares to receive key identification. Key identification is accom plished 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 identification. The type of each identified key is set to the value indicated by the command. Although these commands can be sent using any code set, they affect only scan code set 3 op eration.

FEH - Resend

The host sends this command when it detects an error in any transmission from the HT82K628A. It is sent only after 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).

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Preliminary

HT82K628A

Commands to the host

The following table shows the commands that the HT82K628A may send to the host, and their hexadecimal 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 HT82K628A sends a key detection error 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. For sets 2 and 3, the code 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 scan code 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, discontinues scanning and sends 2 ID bytes. The low byte is sent first followed by the high byte. Following the output ofKeyboard 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 in dicates keyboard failure.

FCH - BAT failure code

If a BAT failure occurs, the HT82K628A sends this code, discontinues scanning and waits for a host response or reset.

FEH - Resend

The HT82K628A issues a Resend command fol lowing receipt of an invalid input or any input with incorrect parity. If the host sends nothing to the HT82K628A, no response is required.

Data communications

Data output

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

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

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

Data will be valid before the trailing edge and beyond 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.

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Preliminary

HT82K628A

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 on the "data" line. If the line is active it is forced 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 "data" line is found to be at an inactive level following the 10th bit, a frame error has occurred, and the keyboard contin ues to count until the "data" line becomes ac tive. The keyboard then makes the "data" line inactive and sends a Resend.

Data stream

Mode 1,2,3

B1:

start bit

always 0

B2:

b3: b4: b5: B6 b7: b8: b9:

b10:

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)

b11:

stop bit

always 1

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.

8 July 20, 2000

+ 17 hidden pages

Holtek Semiconductor Inc HT82K628A Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual

Features

General Description

Pin Assignment

Pin Description

Absolute Maximum Ratings

Electrical Characteristics

Functional Description