Order of Keypress Detection

Some applications require detection of the specific

sequence of keys in software by looking for unique key

presses within 32 ticks (1s). If the duration between

keypresses exceeds the allowed time, assume the key-

press is in error and return to the previous known state.

Power-Up Jack Detect and Keypress

Example

Figure 10 illustrates the FIFO entries during a typical

sequence of events.

Layout, Grounding, and Bypassing

close to the device as possible. Connect GND to a

quiet analog ground plane. Route digital lines away

from SENSE and FORCE.

Wired Remote Controllers

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13

Figure 9. Jack Insertion Detection

➂

➁

➀➃

KEY TYPE

JACK

REMOVED

JACK

DETECTED

FALSE

KEYS

TIME

TIME

1. JACK INSERTION DETECTED AND ENTERED IN FIFO.

2. JACK REMOVAL DETECTED AND ENTERED IN FIFO.

3. JACK INSERTION DETECTED AND ENTERED IN FIFO.

4. FIFO IS READ UNTIL EMPTY (

INT GOES HIGH).

THE LAST READ BEFORE THE EMPTY FIFO IS REACHED

IS THE FINAL STATE OF THE JACK DETECTION.