Nec switch Uživatelský manuál stáhnout pdf (Strana 176)

CHAPTER 11 INTERRUPT FUNCTIONS

User’s Manual U12978EJ3V0UD

176

Figure 11-14. Example of Multiplexed Interrupt Servicing

Example 1. Acknowledging multiplexed interrupts

INTyy

Main processing

INTyy processingINTxx processing

RETI

IE = 0

INTxx

RETI

IE = 0

The interrupt request INTyy is acknowledged and multiplexed interrupt servicing is performed during the interrupt

INTxx servicing. Before each interrupt is acknowledged, the IE instruction is issued and interrupt requests are

enabled.

Example 2. Multiplexed interrupts are not performed because interrupts are disabled.

INTyy

Main processing

RETI

INTyy processingINTxx processing

IE = 0

INTxx

RETI

INTyy is held pending

IE = 0

Interrupt requests are disabled (EI instruction is not issued) in the interrupt INTxx servicing. The interrupt request

INTyy is not acknowledged and multiplexed interrupt servicing is not performed. INTyy is held pending and is

acknowledged after INTxx servicing is completed.

IE = 0: Interrupt request acknowledgment disabled.

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