Interrupt Control Mode 1; Figure 5.6 State Transition In Interrupt Control Mode 1 - Renesas H8S/2158 User Manual

Section 5 Interrupt Controller
5.6.2

Interrupt Control Mode 1

In interrupt control mode 1, mask control is applied to three levels for IRQ and on-chip peripheral
module interrupt requests by comparing the I and UI bits in CCR in the CPU, and the ICR setting.
Note however that the KIN, WUE, and DTI interrupt requests can be accepted when the I bit is
cleared to 0 and are held pending when the I bit is set to 1.
1. An interrupt request with interrupt control level 0 is accepted when the I bit in CCR is cleared
to 0. When the I bit is set to 1, the interrupt request is held pending.
2. An interrupt request with interrupt control level 1 is accepted when the I bit or UI bit in CCR is
cleared to 0. When both I and UI bits are set to 1, the interrupt request is held pending.
For instance, the state transition when the interrupt enable bit corresponding to each interrupt is set
to 1, and ICRA to ICRD are set to H'20, H'00, and H'00, respectively (IRQ2 and IRQ3 interrupts
are set to interrupt control level 1, and other interrupts are set to interrupt control level 0) is shown
below. Figure 5.6 shows a state transition diagram.
1. All interrupt requests are accepted when I = 0. (Priority order: NMI > IRQ2 > IRQ3 > IRQ0 >
IRQ1 > address break ...)
2. Only NMI, IRQ2, IRQ3, and address break interrupt requests are accepted when I = 1 and UI =
0.
3. Only NMI and address break interrupt requests are accepted when I = 1 and UI = 1.
All interrupt requests
are accepted
Exception handling execution
or I 1, UI

Figure 5.6 State Transition in Interrupt Control Mode 1

Rev. 3.00 Jan 25, 2006 page 94 of 872
REJ09B0286-0300
I
I 1, UI
I 0
1
Only NMI and address break
interrupt requests are accepted
0
Only NMI, address break, and
interrupt control level 1 interrupt
0
requests are accepted
UI 0
Exception handling
execution or UI 1