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User’s Manual U11969EJ3V0UM00
CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
(1) To accept maskable interrupts in service routine
Service routine of maskable interrupt or exception
...
...
• Saves EIPC to memory or register
• Saves EIPSW to memory or register
• EI instruction (enables interrupt acceptance)
...
...
←
Accepts maskable interrupt.
...
...
• DI instruction (disables interrupt acceptance)
• Restores saved value to EIPSW
• Restores saved value to EIPC
• RETI instruction
(2) To generate exception in service program
Service program of maskable interrupt or exception
...
...
• Saves EIPC to memory or register
• Saves EIPSW to memory or register
...
• TRAP instruction
←
Accepts exception such as TRAP instruction
• Illegal op code
←
Accepts exception such as illegal op code
...
• Restores saved value to EIPSW
• Restores saved value to EIPC
• RETI instruction
Priorities 0 to 7 (0 is the highest priority) can be programmed for each maskable interrupt request for multiple
interrupt processing control. To set a priority level, write values to the xxPRn0 to xxPRn2 bits of the interrupt
request control register (xxICn) corresponding to each maskable interrupt request. At system reset, the
interrupt request is masked by the xxMKn bit, and the priority level is set to 7 by the xxPRn0 to xxPRn2 bits.
The priorities of maskable interrupts are as follows:
(High) Level 0 > Level 1 > Level 2 > Level 3 > Level 4 > Level 5 > Level 6 > Level 7 (Low)
Interrupt processing that has been suspended as a result of multiple interrupt processing is resumed after the
interrupt processing of the higher priority has been completed and the RETI instruction has been executed.
A pending interrupt request is accepted after the current interrupt processing has been completed and the
RETI instruction has been executed.
Caution
In the non-maskable interrupt processing routine (time until the RETI instruction is executed),
maskable interrupts are not accepted but are suspended.
Remarks xx: Each peripheral unit identifier (OV, CC0, P1, CM1, CM2, CC3, CS, II, SE, SR, ST, AD, P5)
n:
Peripheral unit number (0 to 4)
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