lm8322 National Semiconductor Corporation, lm8322 Datasheet - Page 35

• Manufacturer Part Number: lm8322
• Description: Mobile I/o Companion Supporting Key-scan, I/o Expansion, Pwm, And Access.bus Host Interface
• Manufacturer: National Semiconductor Corporation

17.14 SET_DEBOUNCE COMMAND
The SET_DEBOUNCE command consists of a command
byte (0x8F) and a data byte from the host. This command sets
the time that the LM8322 waits before rescanning the keypad
to confirm a key-press or key-release event. The default de-
17.15 SET_KEY_SIZE COMMAND
The SET_KEY_SIZE command consists of a command byte
(0x90) and a data byte from the host. This command specifies
the keypad size in terms of the number of KP-Xx inputs and
KP-Yx outputs which are used. Any unused KP-Xx and KP-
Yx pins may be used for general-purpose I/O. The minimum
17.16 READ_KEY_SIZE COMMAND
The READ_KEY_SIZE command consists of a command
byte (0x91) from the host and a data byte from the LM8322.
7
1
7
1
7
1
DEBOUNCETIME
6
0
Field
KP-X
KP-Y
Field
KP-X
KP-Y
6
0
6
0
Field
5
0
5
0
5
0
4
0
3
1
4
1
4
1
Value
Value
3–12
3–12
3–8
2
1
3–8
3
0
3
0
1
1
1–255
Value
2
0
2
0
Number of KP-Xx inputs.
Number of KP-Yx outputs.
0
1
Number of KP-Xx inputs.
Number of KP-Yx outputs.
1
0
1
0
7
Active time = n × 4 milliseconds.
0
0
0
1
35
6
7
7
bounce time is 12 milliseconds. The host can program DE-
BOUNCETIME from 4–1020 milliseconds with a granularity
of 4 milliseconds. The DEBOUNCETIME must not exceed the
active time set with the SET_ACTIVE command.
value for either field is 3, which corresponds to a keypad con-
figuration that supports 3 × 3 + 3 SF keys (total of 12 keys).
The maximum number of KP-Xx inputs is 8, and the maximum
number of KP-Yx outputs is 12. If the digital multiplexer MUX2
is used, the maximum number of KP-Yx outputs is 9. If the
SLOWCLKOUT pin is used, the maximum number is 8.
The host can issue the command at any time to read the con-
figuration of the keypad.
5
6
6
KP-X
KP-X
DEBOUNCETIME
Description
Description
5
5
4
Description
4
4
3
3
3
2
2
2
KP-Y
KP-Y
1
1
1
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0
0
0