
7542 Group
Rev.3.02 Oct 31, 2006 Page 29 of 134
REJ03B0006-0302
Key Input Interrupt (Key-On Wake-Up)
A key-on wake-up interrupt request is generated by applying “L”
level to any pin of port P0 that has been set to input mode.
In other words, it is generated when the AND of input level goes
from “1” to “0”. An example of using a key input interrupt is shown
in Figure 25, where an interrupt request is generated by pressing
one of the keys provided as an active-low key matrix which uses
ports P0
0
to P0
3
as input ports.
Fig. 25 Connection example when using key input interrupt and port P0 block diagram
Port PXx
“L” level output
PULL register
bit 3 = “0”
Port P0
7
latch
Port P0
7
Direction register = “1”
**
*
P0
7
output
Key input interrupt request
Port P0
Input read circuit
* P-channel transistor for pull-up
** CMOS output buffer
PULL register
bit 3 = “0”
Port P0
6
latch
Port P0
6
Direction register = “1”
**
*
P0
6
output
PULL register
bit 3 = “0”
Port P0
5
latch
Port P0
5
Direction register = “1”
**
*
P0
5
output
PULL register
bit 3 = “0”
Port P0
4
latch
Port P0
4
Direction register = “1”
**
*
P0
4
output
PULL register
bit 2 = “1”
Port P0
3
latch
Port P0
3
Direction register = “0”
**
*
P0
3
input
PULL register
bit 2 = “1”
Port P0
2
latch
Port P0
2
Direction register = “0”
**
*
P0
2
input
PULL register
bit 1 = “1”
Port P0
1
latch
Port P0
1
Direction register = “0”
**
*
P0
1
input
PULL register
bit 0 = “1”
Port P0
0
latch
Port P0
0
Direction register = “0”
**
*
P0
0
input
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Port P0
0
key-on wakeup
selection bit
Port P0
6
key-on wakeup
selection bit
Port P0
4
key-on wakeup
selection bit