
7534 Group
Rev.3.00 Oct 23, 2006 page 18 of 53
REJ03B0099-0300
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 Fig-
ure 18, where an interrupt request is generated by pressing one of
the keys provided as an active-low key matrix which uses ports P00
to P03 as input ports.
Fig. 18 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
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