NEC 78K0R/KE3 User Manual page 596

Example 3. Multiple interrupt servicing does not occur because interrupts are not enabled
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 = 00: Specify level 0 with ××PR1× = 0, ××PR0× = 0 (higher priority level)
PR = 01: Specify level 1 with ××PR1× = 0, ××PR0× = 1
PR = 10: Specify level 2 with ××PR1× = 1, ××PR0× = 0
PR = 11: Specify level 3 with ××PR1× = 1, ××PR0× = 1 (lower priority level)
IE = 0: Interrupt request acknowledgment is disabled
IE = 1: Interrupt request acknowledgment is enabled.
596
CHAPTER 15 INTERRUPT FUNCTIONS
Figure 15-10. Examples of Multiple Interrupt Servicing (2/2)
Main processing
IE = 0
EI
INTxx
(PR = 11)
IE = 1
1 instruction execution
User's Manual U17854EJ9V0UD
INTxx servicing INTyy servicing
INTyy
(PR = 00)
RETI
IE = 0
RETI
IE = 1