ht82k628a Holtek Semiconductor Inc., ht82k628a Datasheet - Page 4

• Manufacturer Part Number: ht82k628a
• Description: Ht82k628a -- Windows 2000 Ps/2 Keyboard Encoder
• Manufacturer: Holtek Semiconductor Inc.

F3H - Set Typematic Rate/Delay
The host issues the Set Typematic Rate/Delay com-
mand 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/de-
lay 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 previ-
ously 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:
The default values for the HT82K628A are as follows:
Typematic rate= 10.9 characters per second
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.
Rev. 1.60
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
Bit
Rate ± 20%
Typematic
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
8.0
8.0
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
Bit
Rate ± 20%
Typematic
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
20%
4
F4H - Enable
Upon receipt of this command, the HT82K628A will re-
spond with ACK, clears its output buffer, clears the last
typematic key, and starts scanning.
F5H - Default Disable
The Default Disable command resets all conditions to
the power on default states. The HT82K628A will re-
spond 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 operation only) and typematic
rate/delay, and clears the last typematic key then contin-
ues scanning.
F7H, F8H, F9H, FAH - Set All Keys
These commands instruct the HT82K628A to set all
keys to the type listed below:
The HT82K628A will respond with ACK, clears its output
buffer, sets all keys to the type indicated by this com-
mand, and continues scanning (if it was previously en-
abled). Although these commands can be sent using
any code set, they affect only scan code set 3 operation.
FBH, FCH, FDH - Set Key Type
These commands instruct the HT82K628A to set indi-
vidual keys to the type listed below:
The HT82K628A will respond with ACK, clears its output
buffer and prepares to receive key identification. Key
identification is accomplished 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 iden-
tification. The type of each identified key is set to the
value indicated by the command. Although these com-
mands can be sent using any code set, they affect only
scan code set 3 operation.
Hex Value
Hex Value
FA
FB
FC
FD
F7
F8
F9
Set All Keys-Typematic
Set All Keys-Make/Break
Set All Keys-Make
Set All Keys-Typematic/Make/Break
Set Key Type-Typematic
Set Key Type-Make/Break
Set Key Type-Make
Command
Command
HT82K628A
April 16, 2004