7733 datasheet(620/940 Pages) RENESAS

620 / 940 page

7733 Group User’s Manual

21-72

APPENDIX

Interrupt

(1/2)

If an interrupt request (b) occurs while an interrupt routin

e (a) is executed, is it true that the main

routine is not executed at all from when the execution of th

e interrupt routine (a) is completed until the

execution of the INTACK sequence for the next interrupt (b)

starts?

Conditions:

q I = 0 by executing the RTI instruction

q Interrupt priority level of interrupt (b) is higher than IPL of main routine.

q Interrupt priority level detection time = 2 cycles of

An interrupt request is sampled by detecting a sampling puls

e which is generated synchronously with

the CPU’s op-code fetch cycle.

(1)

If the next interrupt request (b) occurs before sampling pul

of the RTI instruction is generated,

sampling for this interrupt request is completed while the RTI instruction is executed.

Therefore, the INTACK sequence for (b) is executed without executing the main routine. (Even

one instruction is not executed.)

Interrupt routine (a)

Main routine

INTACK sequence (b)

Sequence of

execut ion

RTI instruction

INTACK sequence for (b)

Interrupt request (b)

Interrupt routine (a)

Sampling pulse

RTI instruction

Appendix 9. Q & A

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