LG -A290 Service Manual page 49

The keypad can be divided into two parts: one is the keypad interface including 7 columns and 6 rows(A90 is using
5columns and 5rows) with one dedicated power-key, as shown in Figure 3.1.; the other is the key detection block
which provides key pressed, key released and de-bounce mechanisms. Each time the key is pressed or released, i.e.
something different in the 6 x 7 matrix or power-key, the key detection block senses the change and recognizes if a
key has been pressed or released. Whenever the key status changes and is stable, a KEYPAD IRQ is issued. The MCU can
then read the key(s) pressed directly in KP_MEM1, KP_MEM, KP_MEM3, and KP_MEM4 registers. To ensure that the key
pressed information is not missed, the status register in keypad is not read-cleared by APB read command. The status
register can only be changed by the key-pressed detection FSM.
(6x7 + one power-key) key matrix
COL0
ROW5
ROW4
ROW3
ROW2
ROW1
ROW0
LGE Internal Use Only
COL1 COL2 COL3 COL4 COL5 COL6
1 1 1
1 1 1
1 1 1
1 1 1
1 1 1
1 1 1
Figure 3.12.2 6x7 matrix with one power-key
Dedicated for Power-key
1 1 1
1 1 1
1
1 1
1 1 1
1 1 1
1 1 1
Baseband
PMIC integrated BB chip
- 49 - Copyright © 01 LG Electronics. Inc. All right reserved.
3. TECHNICAL BRIEF
PWR_KEY
1 1
1 1
1 1
1 1
1 1
1 1
PMIC
Only for training and service purposes