BU94601KV_12 Datasheet, PDF (29/70 Pages) Rohm – AAC/WMA/MP3 +SD Memory Card + iPod

BU94601KV BU94603KV BU94604BKV
Datasheet
21.1.2
KEY SCAN (Hold Mode)
KEY SCAN operates in the following sequence on the circuit configuration as shown in Figure 9 .
(1) KEY_COL1 to 3 output waveforms at timing as shown in Figure25.
(2) By pressing KEY switch, KEY_ROW 1 to 4 are set to L at timing when KEY_COL 1 to 3 are L.
(3) When detecting L input from KEY_ROW 1 to 4 three times, the master judges that KEY has been
pressed. Then, the master starts judging status of held KEY.
(4) When pressed KEY’s decision (L input from KEY_ROW 1 to 4 three times) is detected consecutive
15 times, the master judges that KEY Mode is Hold Mode.
(5) When KEY release is detected in judging status of hold KEY, the master judges that KEY Mode is
Single Mode. Then, the master starts the KEY operation.
(6) When Hold Mode is detected, the master starts the KEY operation in Hold Mode. When KEY release
is detected in Hold Mode, the master finish the KEY operation.
The keys corresponding to Hold Mode are FF, FB, VOL+, and VOL-.
Figure 27 KEY SCAN Waveform.
Note 1: Based on the above sequence, the master determines that KEY is pressed and starts the operation of the pressed
KEY, pressing multiple KEYs at the same time will produce different operations depending on the KEY
combinations. Therefore, you cannot regulate the operation sequence correctly even simultaneously pressing
multiple KEYs will not cause any problems. In Hold Mode, Other pressed KEY is disregarded.
Note 2: Because the KEY input does not have a buffering function, KEY inputs other than those described below are
ignored.
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TSZ02201-0V2V0E600010-1-2
2012.07.12 Rev.001