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ML9222

21/25

FEDL9222-02

Keyscan

Keyscanning is started only when depression or release of any key is detected in order to

minimize noise caused by scanning signal. Then, keyscanning is continued until the keyscan

stop mode is sent from a microcomputer. The INT pin goes to the high level at the completion

of 1-cycle scanning after the keyscan start, so the (high level) signal sent from the INT pin can be

used as an interrupt signal.

[Keyscan Timing]

1 Cycle

INT

ROW 5

ROW 4

ROW 3

ROW 2

ROW 1

Depress/Release

Keyscan stop mode

is selected.

Note: Keyscanning cannot be stopped by selecting the keyscan stop mode only once if:

- keyscanning is started after depression or release of any key is detected, and then

- a key is depressed or released again before the keyscan stop mode is selected.

To stop keyscanning, it is required to select the keyscan stop mode once again.

Depress

Depress

Release

Keyscan

Keyscan

INT

CS

MODE5

MODE5

MODE5

MODE5 : Keyscan stop