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CHAPTER 15 INTERRUPT FUNCTIONS
Preliminary User’s Manual U16035EJ1V0UM
Figure 15-14. Nesting Examples (2/2)
Example 3. Nesting does not occur because interrupt is not enabled
Interrupt is not enabled during servicing of interrupt INTxx (EI instruction is not issued), therefore, interrupt request
INTyy is not acknowledged and nesting 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 acknowledge disabled
Main processing
INTxx servicing INTyy servicing
EI
1 instruction execution
RETI
RETI
INTxx
(PR = 0)
INTyy
(PR = 0)
IE = 0
IE = 0