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5.3 Interrupt Sources
The interrupt sources include external interrupts (NMI, IRQ
5.3.1 External Interrupts
There are six external interrupts: NMI, and IRQ
can be used to exit software standby mode.
NMI: NMI is the highest-priority interrupt and is always accepted, regardless of the states of the
I and UI bits in CCR. The NMIEG bit in SYSCR selects whether an interrupt is requested by the
rising or falling edge of the input at the NMI pin. NMI interrupt exception handling has vector
number 7.
IRQ
The IRQ
•
•
•
Figure 5-2 shows a block diagram of interrupts IRQ
IRQn
Note: n = 4 to 0
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to IRQ
Interrupts: These interrupts are requested by input signals at pins IRQ
0
4
to IRQ
interrupts have the following features.
0
4
ISCR settings can select whether an interrupt is requested by the low level of the input at pins
IRQ
to IRQ
, or by the falling edge.
0
4
IER settings can enable or disable the IRQ
assigned by four bits in IPRA (IPRA7 to IPRA4).
The status of IRQ
to IRQ
interrupt requests is indicated in ISR. The ISR flags can be
0
4
cleared to 0 by software.
IRQnSC
Edge/level
sense circuit
input
Figure 5-2 Block Diagram of Interrupts IRQ
to IRQ
) and 21 internal interrupts.
0
4
to IRQ
. Of these, NMI, IRQ
0
4
to IRQ
interrupts. Interrupt priority levels can be
0
4
to IRQ
.
0
4
IRQnE
IRQnF
S
Q
R
Clear signal
to IRQ
0
88
, IRQ
, and IRQ
0
1
2
to IRQ
.
0
4
IRQn interrupt
request
4
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