
deveopmen
Interrupts
Preliminary Specifications REV.D
Specifications in this manual are tentative and subject to change.
Mitsubishi microcomputers
M16C/80 (100-pin version) group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
70
Interrupt control circuit
Key input interrupt control register
(address 0093
16
)
Key input interrupt
request
P10
7
/KI
3
P10
6
/KI
2
P10
5
/KI
1
P10
4
/KI
0
Port P10
4
-P10
7
pull-up
select bit
Port P10
7
direction
register
Pull-up
transistor
Port P10
7
direction register
Port P10
6
direction
register
Port P10
5
direction
register
Port P10
4
direction
register
Pull-up
transistor
Pull-up
transistor
Pull-up
transistor
Figure 1.9.10. Block diagram of key input interrupt
NMI Interrupt
An NMI interrupt is generated when the input to the P8
5
/NMI pin changes from “H” to “L”. The NMI interrupt
is a non-maskable external interrupt. The pin level can be checked in the port P8
5
register (bit 5 at address
03C4
16
).
This pin cannot be used as a normal port input.
Notes:
When not intending to use the NMI function, be sure to connect the NMI pin to V
CC
(pulled-up). The NMI
interrupt is non-maskable. Because it cannot be disabled, the pin must be pulled up.
Key Input Interrupt
If the direction register of any of P10
4
to P10
7
is set for input and a falling edge is input to that port, a key
input interrupt is generated. A key input interrupt can also be used as a key-on wakeup function for cancel-
ling the wait mode or stop mode. However, if you intend to use the key input interrupt, do not use P10
4
to
P10
7
as A-D input ports. Figure 1.9.10 shows the block diagram of the key input interrupt. Note that if an “L”
level is input to any pin that has not been disabled for input, inputs to the other pins are not detected as an
interrupt.
Setting the key input interrupt disable bit (bit 7 at address 03AF
16
) to “1” disables key input interrupts from
occurring regardless of the setting in the interrupt control register. When “1” is set in the key input interrupt
disable register, there is no input via the port pin even when the direction register is set to input.