Keypad Interface - LG -T300 Service Manual

3. TECHNICAL BRIEF

3.11 Keypad Interface

3.11 Keypad Interface
VRTC
END_KEY
ZD206
KP_OUT1
R237 680
KP_IN2
R215 680
KP_OUT2
R238 680
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.
LGE Internal Use Only
PWR/HOLD
CN202
1
2
3
C248
0.1u
VOLUME
CN203
1
2
3
ZD212 ZD207 ZD213
Figure 3-11-1 MAIN KEY STRUCTURE
3. TECHNICAL BRIEF
KEYPAD INTERFACE
KP_OUT1
R239 680
KP_OUT2
R240 680
KP_OUT3
R241 680
KP_IN3
R205 680
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Copyright © 2010 LG Electronics. Inc. All right reserved.
SEND OK
KB203 KB202
ZD208 ZD209 ZD210
Only for training and service purposes
END
KB201
ZD211