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Rev. 1.00, 05/04, page 63 of 544
4.4 Interrupt Exception Handling
Interrupts are controlled by the interrupt controller. The sources to start interrupt exception
handling are external interrupt sources (NMI, IRQ7 to IRQ0, KIN15 to KIN0, and WUE7 to
WUE0) and internal interrupt sources from the on-chip peripheral modules. NMI is an interrupt
with the highest priority. For details, refer to section 5, Interrupt Controller.
Interrupt exception handling is conducted as follows:
1. The values in the program counter (PC) and condition code register (CCR) are saved to the
stack.
2. A vector address corresponding to the interrupt source is generated, the start address is loaded
from the vector table to the PC, and program execution begins from that address.
4.5 Trap Instruction Exception Handling
Trap instruction exception handling starts when a TRAPA instruction is executed. Trap instruction
exception handling can be executed at all times in the program execution state.
Trap instruction exception handling is conducted as follows:
1. The values in the program counter (PC) and condition code register (CCR) are saved to the
stack.
2. A vector address corresponding to the interrupt source is generated, the start address is loaded
from the vector table to the PC, and program execution starts from that address.
The TRAPA instruction fetches a start address from a vector table entry corresponding to a vector
number from 0 to 3, as specified in the instruction code.
Table 4.3 shows the status of CCR after execution of trap instruction exception handling.
Table 4.3 Status of CCR after Trap Instruction Exception Handling
CCR
Interrupt Control Mode I UI
0 1 —
1 1 1
[Legend]
1: Set to 1
—: Retains value prior to execution