LM8322 datasheet(35/42 Pages) NSC

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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-

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.

DEBOUNCETIME

Field

Value

Description

DEBOUNCETIME

1–255

Active time = n × 4 milliseconds.

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

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.

KP-X

KP-Y

Field

Value

Description

KP-X

3–8

Number of KP-Xx inputs.

KP-Y

3–12

Number of KP-Yx outputs.

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.

The host can issue the command at any time to read the con-

figuration of the keypad.

KP-X

KP-Y

Field

Value

Description

KP-X

3–8

Number of KP-Xx inputs.

KP-Y

3–12

Number of KP-Yx outputs.

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