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HT82K28A Win98 Keyboard Encoder

· Designed for Windows 95 / 98 / NT · Supports 3 Windows 95 Keys · Supports Power, Sleep and Wake-up Windows 98 · Supports code set 2, for PC / AT, PS / 2 model 50, 60

HT82K28A Win98 Keyboard Encoder
Features
· Designed for Windows 95 / 98 / NT · Supports 3 Windows 95 Keys · Supports Power, Sleep and Wake-up Windows 98 · 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 · 40-pin DIP package
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 especially 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 in which data is stored. An inexpensive RC oscillator can be used for the system clock. The device offers the advantage of simple implementation in high performance and low cost keyboard applications.
Pin Assignment
Rev. 1.30
June 27, 2002
HT82K28A
Pin Description
R0~R18
Keyboard matrix scanning output pins
NC SCRL NUM CAP CLOCK DATA
No connection LED pin LED pin LED pin Synchronous clock signal. Used to clock the transmission data Bidirectional data transmission line
Absolute Maximum Ratings
Supply Voltage ....................4.75V to 5.25V Storage Temperature ..............-55°C to 125°C Input Voltage...............VSS-0.3V to VDD+0.3V Operating Temperature................0°C to 70°C
Electrical Characteristics
Rev. 1.30
June 27, 2002
HT82K28A
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 system 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 released 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 1
· Supports code set 1 for PS / 2 model 30 keyboards. · Enters mode1 after an F0 Command is issued fol-
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:
· 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
Power-on Two important activities take place when power is first applied to the keyboard. The first is the presence of an H / W signal POR (Power-On-Reset) that resets the keyboard processor. The second activity is the running of the self test BAT (Basic Assurance Test) routine.
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 parity bit (odd parity) and one stop bit (always one) · All keys are typematic / make / break as default. Mode 3
· Supports code set 3, for PS / 2 model 80 keyboards. · Enters mode 3 when an F0 command is issued fol-
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 PC-AT PS / 2 50 PS / 2 60 PS / 2 80 mode 1 mode 2 mode 2 mode 2 mode 3 code set 1 code set 2 code set 2 code set 2 code set 3
· 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). 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 po-
The mode can be changed between mode 2 & 3.
sitions.
Rev. 1.30
June 27, 2002
HT82K28A
· 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 following:
If a key is pressed and held down while keyboard transmission is inhibited, only the first make code is stored in the buffer overflow as a result of typematic action. Four key types are supported as shown: Key type Typematic Make / break Make Typematic / make / break Note: press make1 make1 make1 make1 hold make2 X X make2 release X break X break
· For code set 3
Typematic Make / break Make Typematic / make / break Can be configured by 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.
System command table Command FF - reSset 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 mode 1 y y y y y y y y y y y y y y x y x y y mode 2 y y y y y y y y y y y y y y x y x y y mode 3 y y y y y y y y y y y y y y x y x y y
Rev. 1.30
June 27, 2002
HT82K28A
Command description
· Default disable - F5
· Set all keys - F7, F8, F9, FA
FA: Set all keys to typematic / make / break F9: Set all keys to make F8: Set all keys to make / break F7: Set all keys to typematic Send an ACK to the system Clear output buffer Set all keys to the type indicated by the command
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 instruction
· Set default - F6
Send an EE to the system Continue scanning if the keyboard is enabled Note: This command does not need to feed back the ACK
Send an ACK to the system Clear the output buffer Set to default key states: Default key type typematic rate / delay
· Enable - F4
· Set key type - FB, FC, FD
Send an ACK to the system Clear output buffer Clear the last typematic key Start scanning
FB : Set key type - Typematic FC : Set key type - Make / Break FD : Set key type - Make The keyboard responds with ACK, clears its output buffer and prepares to receive key identification Key identification is accomplished by the system identifying each key by its scan code value as defined in scan code set3. Only scan code set3 values are valid for key identification The type of each identified key is set to the value indicated by the command These commands can be sent using any scan code set, but affect only the operation of scan code set3
· Invalid command
Send an FE to the system No further activities Note: No ACK
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
Send ACK to the system Discontinue scanning Wait for the option from the system Respond with ACK to the system Set indicator If command comes from the system in place of option, discard the set LED function and then process the new command LED default after power on - all off Set default disable - do not change the LEDs
· Resend - FE
Send the last code to the system Note: No FA response
· Reset - FF
· Set typematic rate / delay - F3
Send an ACK to the system Stop scanning Wait for the system typematic rate and delay Send an ACK to the system Set rate / delay Bit 6, 5 delay Bit 4, 3, 2, 1, 0 typematic rate
· Select alternate scan code - F0
Send an ACK to the system Clears both output buffer and the typematic key Accept option byte
Rev. 1.30
June 27, 2002
HT82K28A
Data communications
· Data output
b4~b0 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111
· Default
Typematic rate 30.0 26.7 24.0 21.8 20.0 18.5 17.1 16.0 15.0 13.3 12.0 10.9 10.0 9.2 8.6 8.0
b4~b0 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111
Typematic rate 7.5 6.7 6.0 5.5 5.0 4.6 4.3 4.0 3.7 3.3 3.0 2.7 2.5 2.3 2.1 2.0
· Data input
Commands to the system 00: keyboard detect a error / overrun (set 2, set 3) AB, 83: keyboard ID AA: BAT completion FC: BAT failure EE: Echo FA: Acknowledge FE: Resend FF: Keyboard detects a overrun (set 1)
· FA: Acknowledge
If the KB (Keyboard) receives any valid input except EE (echo) and resend (FE) then send an FA to the system first. If the command is EE, then send an EE back to the system. If the command is FE, then send the last key code to system. If there is an interrupt while sending FA, the KB discards the FA and accepts the command from the system and processes it.
· 00 / FF: Key overrun
If the keyboard detects an overrun error, the KB sends an overrun error code to the system. mode 1: FF mode 2, 3: 00
· FE: Resend
Note:
The KB issues an FE when there is a parity error in transmission.
Rev. 1.30
June 27, 2002
HT82K28A
Rev. 1.30
June 27, 2002
HT82K28A
When both shift keys are held down: key number 75 Key Number 95 when both shift keys are held down: key number 95 Base E0 35 / E0 B5
Both Shift E0 AA E0 B6 E0 52 / E0 D2 E0 2A E0 36 +Left-Shift E0 AA E0 35 / E0 B5 E0 2A Both Shift E0 AA E0 B6 E0 35 / E0 B5 E0 2A E0 36 Base +Left-Shift E0 37 / E0 B7 +Ctrl E0 46 E0 C6 +Right-Shift 54 / D4 +Right-Shift E0 B6 E0 35 / E0 B5 E0 36
Key Number 124 Key Number 126
E0 2A E0 37 / E0 B7 E0 AA Base E1 1D 45 E1 9D C5
This key is not typematic, all associated scan codes occur on the make code. Key Power Sleep Wake Make E0 5E E0 5F E0 63 Break E0 DE E0 DF E0 E3 Windows Virtual Key N / A N / A N / A
Rev. 1.30
June 27, 2002
HT82K28A
Rev. 1.30
June 27, 2002
HT82K28A
Key code set 2 Key Number 75 76 79 80 81 83 84 85 86 89 L Win R Win APP Base Case Shift+Num E0 70 / E0 F0 72 E0 71 / E0 F0 71 E0 6B / E0 F0 6B E0 6C / E0 F0 6C E0 69 / E0 F0 69 E0 75 / E0 F0 75 E0 72 / E0 F0 72 E0 7D / E0 F0 7D E0 7A / E0 F0 7A E0 74 / E0 F0 74 E0 1F / E0 F0 1F E0 27 / E0 F0 27 E0 2F / E0 F0 2F Left-Shift E0 F0 12 E0 70 / E0 F0 70 E0 12 E0 F0 12 E0 70 / E0 F0 71 E0 12 E0 F0 12 E0 70 / E0 F0 6B E0 12 E0 F0 12 E0 70 / E0 F0 6C E0 12 E0 F0 12 E0 70 / E0 F0 69 E0 12 E0 F0 12 E0 70 / E0 F0 75 E0 12 E0 F0 12 E0 70 / E0 F0 72 E0 12 E0 F0 12 E0 70 / E0 F0 7D E0 12 E0 F0 12 E0 70 / E0 F0 7A E0 12 E0 F0 12 E0 70 / E0 F0 74 E0 12 E0 F0 12 1F / E0 F0 1F E0 12 E0 F0 12 27 / E0 F0 27 E0 12 E0 F0 12 2F / E0 F0 2F E0 12 Right-Shift E0 F0 59 E0 70 / E0 F0 70 E0 59 E0 F0 59 E0 71 / E0 F0 71 E0 59 E0 F0 59 E0 6B / E0 F0 6B E0 59 E0 F0 59 E0 6C / E0 F0 6C E0 59 E0 F0 59 E0 69 / E0 F0 69 E0 59 E0 F0 59 E0 75 / E0 F0 75 E0 59 E0 F0 59 E0 72 / E0 F0 72 E0 59 E0 F0 59 E0 7D / E0 F0 7D E0 59 E0 F0 59 E0 7A / E0 F0 7A E0 59 E0 F0 59 E0 74 / E0 F0 74 E0 59 E0 F0 59 E0 1F / E0 F0 1F E0 59 E0 F0 59 E0 27 / E0 F0 27 E0 59 E0 F0 59 E0 2F / E0 F0 2F E0 59 Both Shift E0 F0 12 E0 F0 59 E0 70 / E0 F0 70 E0 12 E0 59 Base E0 4A / E0 F0 4A +Left-Shift E0 F0 12 E0 4A / E0 F0 4A E0 12 Both Shift E0 F0 12 E0 F0 59 E0 4A / E0 F0 4A E0 12 E0 59 Base E0 12 E0 7C / E0 F0 7C E0 12 Base E1 14 77 E1 F0 14 F0 77 +Shift / +Ctrl E0 7C / E0 F0 7C +Alt 84 / F0 84 +Ctrl E0 7E E0 F0 7E +Right-Shift E0 F0 59 E0 4A / E0 F0 4A E0 59 Num Lock E0 12 E0 70 / E0 F0 70 E0 F0 12 E0 12 E0 71 / E0 F0 71 E0 F0 12 E0 12 E0 6B / E0 F0 6B E0 F0 12 E0 12 E0 6C / E0 F0 6C E0 F0 12 E0 12 E0 69 / E0 F0 69 E0 F0 12 E0 12 E0 75 / E0 F0 75 E0 F0 12 E0 12 E0 72 / E0 F0 72 E0 F0 12 E0 12 E0 7D / E0 F0 7D E0 F0 12 E0 12 E0 7A / E0 F0 7A E0 F0 12 E0 12 E0 74 / E0 F0 74 E0 F0 12 E0 12 E0 1F / E0 F0 1F E0 F0 12 E0 59 E0 27 / E0 F0 27 E0 F0 12 E0 59 E0 2F / E0 F0 2F E0 F0 59
When both shift keys are held down: key number 75
Key Number 95 When both shift keys are held down: key number 95
Key Number 124 Key Number 126
Note: this key is not typematic, all associated scan codes occur on the make of the key. key Power Sleep Wake Make E0 37 E0 3F E0 5E Break E0 F0 37 E0 F0 3F E0 F0 5E Windows Virtual Key N / A N / A N / A
Rev. 1.30
June 27, 2002
HT82K28A
Different from code set 2
Rev. 1.30
June 27, 2002
HT82K28A
Timing Diagrams
Data output
Keyboard data input
Rev. 1.30
June 27, 2002
HT82K28A
Application Circuits
Rev. 1.30
June 27, 2002
HT82K28A
The above key code is according to the Microsoft specification except for the following keys. Key No 14 94 109 129 130 Code Set 1 Make / Break 7D 7C 78 F1 F0 FD FC F8 Code Set 2 Make / Break 6A 68 63 F1 F2 F0 6A F0 68 F0 63 Code Set 3 Make / Break 5D 68 78 F1 F2 F0 5D F0 68 F0 78
Rev. 1.30
June 27, 2002
HT82K28A
Package Information
40-pin DIP (600mil) outline dimensions
Rev. 1.30
June 27, 2002
HT82K28A
Rev. 1.30
June 27, 2002