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CHAPTER 12 INTERRUPT FUNCTIONS
User’s Manual U15104EJ2V0UD
Figure 12-13. Multiple Interrupt Servicing Example (2/2)
Example 3. Example where multiple interrupt does not occur because interrupts are not enabled
Because interrupts are not enabled (EI instruction is not issued) in interrupt servicing INTxx, interrupt
request INTyy is not acknowledged, and multiple interrupt does not occur. The INTyy request is held
pending, and is acknowledged after one instruction of the main routine has been executed.
PR = 0: High priority level
IE = 0:
Acknowledging interrupts is disabled.
Main processing
INTxx
service
INTyy
service
INTxx
(PR = 0)
1 instruction
execution
IE = 0
INTyy
(PR = 0)
IE = 0
RETI
RETI
EI