Interrupt Control Mode 0 - Renesas H8S/2100 Series Hardware Manual

6-bit single-chip microcomputer

Hide thumbs Also See for H8S/2100 Series:

Table of Contents

Table 6.9 shows operations and control signal functions in each interrupt control mode.

Operations and Control Signal Functions in Each Interrupt Control Mode

Control Mode INTM1

Interrupt operation control is performed

Used as an interrupt mask bit

Priority is set

Interrupt Control Mode 0

In interrupt control mode 0, interrupt requests other than NMI and address break are masked by

ICR and the I bit of CCR in the CPU. Figure 6.7 shows a flowchart of the interrupt acceptance

1. If an interrupt source occurs when the corresponding interrupt enable bit is set to 1, an

interrupt request is sent to the interrupt controller.

2. According to the interrupt control level specified in ICR, the interrupt controller only accepts

an interrupt request with interrupt control level 1 (priority), and holds pending an interrupt

request with interrupt control level 0 (no priority). If several interrupt requests are issued, an

interrupt request with the highest priority is accepted according to the priority order, an

interrupt handling is requested to the CPU, and other interrupt requests are held pending.

3. If the I bit in CCR is set to 1, the interrupt controller holds pending interrupt requests other

than NMI and address break. If the I bit is cleared to 0, any interrupt request is accepted.

4. When the CPU accepts an interrupt request, it starts interrupt exception handling after

execution of the current instruction has been completed.

5. The PC and CCR are saved to the stack area by interrupt exception handling. The PC saved on

the stack shows the address of the first instruction to be executed after returning from the

interrupt handling routine.

6. Next, the I bit in CCR is set to 1. This masks all interrupts except for NMI and address break

Interrupt Acceptance

3-Level Control

Rev. 1.00 May 09, 2008 Page 133 of 954

Section 6 Interrupt Controller

Default Priority

Determination

REJ09B0462-0100