3. TECHNICAL BRIEF
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3.11 Keypad Interface
Figure 3-11-1 MAIN KEY STRUCTURE
3. TECHNICAL BRIEF
The Keypad Interface is a peripheral controller, which can be used for scanning external keypad matrices
with up to 8 rows and 8 columns (that is 64 standard keys). By adding an additional row of keys connected
to ground the number of keys can be extended by up to 8 keys. This results in a maximum number of 72
keys to by identified by the Keypad Interface Controller.
The Keypad Scan Module reduces the number of interrupts and polling through the processor and
therefore reduces the power consumption. The module is able to debounce and scan the external keypad
matrix automatically without any software intervention. After debouncing it generates an interrupt. The
interface controller contains information about the key (or key combination) that was pressed and how
long it was pressed.
CN301
3
2
1
D302
ZD304
ZD305
R321
680
680
R322
R330
6.8K
0.1u
C332
VRTC
680
R306
CN302
3
2
1
VRTC
KEY_COL2
KEY_ROW1
KEY_ROW2
END_KEY
PWR/HOLD
VOLUME
3.11 Keypad Interface
1K
R319
100K
R305
D301
PWRON
END_KEY
POWER ON