Datasheet

78K0/Ix2 CHAPTER 18 INTERRUPT FUNCTIONS
R01UH0010EJ0500 Rev.5.00 598
Feb 28, 2012
Figure 18-17. 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
1 instruction execution
RETI
RETI
INTxx
(PR = 0)
INTyy
(PR = 0)
IE = 0
IE = 0
IE = 1
IE = 1
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