NEC PD75402A Manuale Utente

When the interrupt function is used, the following setting are first carried out in the main program.

➀

The interrupt enable flag corresponding to the interrupt to be used is set to “1” (EI IE

×××

 instruction).

➁

If INT0 is used, the active edge is selected (IM0 setting).

➂

The interrupt master enable flag (IME) is set to “1” (EI instruction).

Return from the interrupt service program is by means of an RETI instruction.

➀

  Reset

➁

  EI  IE0

➁

  

EI  IECSI

➂

  EI

➃

  DI  IE0

➄

  DI

INT0 & INTCSI enabled

INTCSI enabled

Interrupts disabled

Interrupts disabled

<Main Program>

➀

All interrupts disabled by RESET input.

➁

Interrupt enable flag set by EI IE

×××

 instruction.

At this stage, all interrupts are still disabled.

➂

Interrupt master enable flag set by EI instruction.

At this stage, INT0 & INTCSI are enabled.

Interrupt enable flag cleared by DI IE

×××

 instruction; INT0 disabled.

➄

All interrupts disabled by DI instruction.

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