UPD78F0411GA-GAM-AX Datasheet, PDF (454/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 17 INTERRUPT FUNCTIONS
Figure 17-10. Examples of Multiple Interrupt Servicing (2/2)
Example 3. Multiple interrupt servicing does not occur because interrupts are not enabled
Main processing
INTxx servicing INTyy servicing
EI
INTxx
(PR = 0)
IE = 0
INTyy
(PR = 0)
RETI
IE = 1
1 instruction execution
IE = 0
IE = 1
RETI
Interrupts are not enabled during servicing of interrupt INTxx (EI instruction is not issued), therefore, interrupt
request INTyy is not acknowledged and multiple interrupt servicing does not take place. The INTyy interrupt request
is held pending, and is acknowledged following execution of one main processing instruction.
PR = 0: Higher priority level
IE = 0: Interrupt request acknowledgment disabled
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User’s Manual U18698EJ1V0UD