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RL78/D1A User's Manual: Hardware - Renesas

RL78/D1A User's Manual: Hardware - Renesas

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Under development<br />

Preliminary document<br />

Specifications in this document are tentative and subject to change.<br />

<strong>RL78</strong>/<strong>D1A</strong> CHAPTER 20 INTERRUPT FUNCTIONS<br />

Figure 20-10. Examples of Multiple Interrupt Servicing (2/2)<br />

Example 3. Multiple interrupt servicing does not occur because interrupts are not enabled<br />

INTxx<br />

(PR = 11)<br />

Main processing INTxx servicing INTyy servicing<br />

EI<br />

1 instruction execution<br />

IE = 0<br />

INTyy<br />

(PR = 00)<br />

IE = 1<br />

R01UH0317EJ0004 Rev. 0.04 1071<br />

Feb. 22, 2013<br />

IE = 0<br />

IE = 1<br />

Interrupts are not enabled during servicing of interrupt INTxx (EI instruction is not issued), therefore, interrupt request<br />

INTyy is not acknowledged and multiple interrupt servicing does not take place. The INTyy interrupt request is held<br />

pending, and is acknowledged following execution of one main processing instruction.<br />

RETI<br />

PR = 00: Specify level 0 with PR1 = 0, PR0 = 0 (higher priority level)<br />

PR = 01: Specify level 1 with PR1 = 0, PR0 = 1<br />

PR = 10: Specify level 2 with PR1 = 1, PR0 = 0<br />

PR = 11: Specify level 3 with PR1 = 1, PR0 = 1 (lower priority level)<br />

IE = 0: Interrupt request acknowledgment is disabled<br />

IE = 1: Interrupt request acknowledgment is enabled.<br />

RETI

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