NEC PD75P402 Manual do Utilizador descarregar pdf (Página 149)

138

CHAPTER 6. INTERRUPT FUNCTIONS

(2) Example using INTBT, INT0 (falling edge active), and INTCSI

➀

Reset

➁

MOV

CLR1

➂

EI



➄

RETI

<INT0 Service Program>

➃

INT0

A, #1

IM0, A

IRQ0

IEBT

IE0

IECSI

; MBE = 0

Status 0

Status 1

Status 0

<Main Program>

➀ All interrupts disabled and status 0 set by RESET input.

➁ INT0 set to falling edge active.

➂ Interrupts enabled by EI and EI IE××× instructions.

On fall of INT0, INT0 interrupt service program is started, status is changed to 1 and all interrupts are

disabled.

➄ RETI instruction effects return from interrupt, restores status to 0, and enables interrupts.

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NEC PD75P402 Manual do Utilizador Página 149