UPD78F0138 NEC, UPD78F0138 Datasheet - Page 376

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

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.
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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
PR = 0: Higher priority level
IE = 0:
Interrupt request acknowledgement disabled
Figure 17-10. Examples of Multiple Interrupt Servicing (2/2)
(PR = 0)
INTxx
1 instruction execution
Main processing
EI
CHAPTER 17 INTERRUPT FUNCTIONS
User’s Manual U16228EJ2V0UD
IE = 1
IE = 0
(PR = 0)
INTyy
IE = 1
INTxx servicing INTyy servicing
IE = 0
RETI
RETI