HT82K28 Holtek Semiconductor Inc, HT82K28 Datasheet - Page 7

• Manufacturer Part Number: HT82K28
• Description: Win98 Keyboard Encoder
• Manufacturer: Holtek Semiconductor Inc

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Resend - FE
Reset - FF
Select alternate scan code - F0
Set all keys - F7, F8, F9, FA
Set default - F6
Set key type - FB,FC,FD
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Send the last code to the system
Note: * No FA response
Disable keyboard
Send an ACK to the system, the keyboard
acknowledges the command with an ACK
and ensures the system accepts the ACK be-
fore executing the command
The system sets CLK=DATA=high for
500ms: acceptance of ACK
The system can issue any command to the
KB within the 500ms period mentioned
above to override FF
If no override, the system performs its BAT
and enters mode 2 (even if it is set to be
mode 3)
Send an ACK to the system
Clears both output buffer and the typematic
key
Accept option byte
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 com-
mand
Send an ACK to the system
Clear the output buffer
Set to default key states: Default key type
typematic rate/delay
FB : Set key type - Typematic
FC : Set key type - Make/Break
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Set LED - ED
Set typematic rate/delay - F3
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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
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
Send an ACK to the system
Stop scanning
Wait for the system typematic rate and de-
lay
Send an ACK to the system
Set rate/delay
Bit 6,5 delay
Bit 4,3,2,1,0 typematic rate
Bit 7=0 (always)
Delay= (1+bit6,bit5) ´ 250ms
Typematic rate= 1/period
...where period= (8+A) ´ (2^B) ´ 0.00417
...where A= binary value of bit 2, 1 and 0
...where B= binary value of bit 4 and 3
February 16, 2000
HT82K28A