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3.2.3
Interrupt Immediately after Reset
After a reset, if an interrupt were to be accepted before the stack pointer (SP: R7) was initialized,
PC and CCR would not be pushed onto the stack correctly, resulting in program runaway. To
prevent this, immediately after reset exception handling all interrupts are masked. For this reason,
the initial program instruction is always executed immediately after a reset. This instruction
should initialize the stack pointer (e.g. MOV.W #xx: 16, SP).
3.3
Interrupts
3.3.1
Overview
The interrupt sources include 13 external interrupts (IRQ
internal interrupts from on-chip peripheral modules. Table 3.2 shows the interrupt sources, their
priorities, and their vector addresses. When more than one interrupt is requested, the interrupt with
the highest priority is processed.
The interrupts have the following features:
• Internal and external interrupts can be masked by the I bit in CCR. When the I bit is set to 1,
interrupt request flags can be set but the interrupts are not accepted.
• IRQ
to IRQ
and WKP
4
0
sensing.
to WKP
can be set to either rising edge sensing or falling edge
7
0
to IRQ
, WKP
to WKP
4
0
7
) and 23
0
65
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