M37544G Mitsubishi Electric, M37544G Datasheet - Page 19

• Manufacturer Part Number: M37544G
• Description: Single-Chip 8-Bit CMOS Microcomputer
• Manufacturer: Mitsubishi Electric

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 21, where an interrupt request is generated by pressing
one of the keys provided as an active-low key matrix which uses
ports P0
Fig. 19 Connection example when using key input interrupt and port P0 block diagram
0
to P0
3
as input ports.
P0
P0
P0
P0
P0
P0
P0
P0
7
6
5
4
3
2
1
0
output
output
output
output
input
input
input
input
Port PXx
“L” level output
Port P0
selection bit
*
*
*
*
*
*
*
*
0
PULL register
bit 3 = “0”
PULL register
bit 3 = “0”
PULL register
bit 3 = “0”
PULL register
bit 3 = “0”
PULL register
bit 2 = “1”
PULL register
bit 2 = “1”
PULL register
bit 1 = “1”
PULL register
bit 0 = “1”
key-on wakeup
**
**
**
**
**
**
**
**
Port P0
latch
Port P0
latch
Port P0
latch
Port P0
latch
Port P0
latch
Port P0
latch
Port P0
latch
Port P0
latch
7
6
5
4
3
2
1
0
Port P0
Direction register = “1”
Port P0
Direction register = “1”
Port P0
Direction register = “1”
Port P0
Direction register = “1”
Port P0
Direction register = “0”
Port P0
Direction register = “0”
Port P0
Direction register = “0”
Port P0
Direction register = “0”
7
6
5
4
3
2
1
0
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
Falling edge
detection
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
** CMOS output buffer
* P-channel transistor for pull-up
MITSUBISHI MICROCOMPUTERS
Key input interrupt request
7544 Group
Port P0
Input read circuit
19