HT82K28A(2000) 데이터 시트보기 (PDF) - Holtek Semiconductor
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HT82K28A Datasheet PDF : 20 Pages
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· Resend - FE
¨ Send the last code to the system
Note: * No FA response
· Reset - FF
¨ 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)
· Select alternate scan code - F0
¨ Send an ACK to the system
¨ Clears both output buffer and the typematic
key
¨ Accept option byte
· 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 com-
mand
· Set default - F6
¨ Send an ACK to the system
¨ Clear the output buffer
¨ Set to default key states: Default key type
typematic rate/delay
· Set key type - FB,FC,FD
¨ FB : Set key type - Typematic
¨ FC : Set key type - Make/Break
HT82K28A
¨ 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
· Set LED - ED
¨ 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
· Set typematic rate/delay - F3
¨ 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
7
February 16, 2000
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