NEC PD75402A - Manual (Page 148)

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CHAPTER 6. INTERRUPT FUNCTIONS
6.6 INTERRUPT APPLICATIONS
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.
(1) Interrupt enabling/disabling
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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