Keypad Interface - LG -T500 Service Manual

3.11 Keypad Interface

KEY_IN[1]
R415 680
KEY_IN[3]
R418 680
KEY_OUT[2]
R419 680
KEY_OUT[3]
R420 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
OK
SEND
KB401
KB402
CLR
KB403
D404 D402 D403
Figure 3-11-1 MAIN KEY STRUCTURE
GPS_ANT2
R427
0
VA401
VA402
CN405
1
2
3
ZD401
- 50 - Copyright © 011 LG Electronics. Inc. All right reserved.
3. TECHNICAL BRIEF
CN403
1
2
3
4
R428
0
VBACKUP_BAT
R413
6.8K
PWR_HOLD
C409
0.1u
Only for training and service purposes