Interrupt Sources; External Interrupts - Renesas H8S Series Hardware Manual

Bit n
IRQnF Description
0 [Clearing conditions]
•
•
•
•
1 [Setting conditions]
•
•
•
•
5.3

Interrupt Sources

Interrupt sources comprise external interrupts (NMI and IRQ7 to IRQ0) and internal interrupts (52 sources).
5.3.1

External Interrupts

There are nine external interrupts: NMI and IRQ7 to IRQ0. Of these, NMI and IRQ2 to IRQ0 can be used to restore the
H8S/2357 Group from software standby mode.
NMI Interrupt: NMI is the highest-priority interrupt, and is always accepted by the CPU regardless of the status of the
CPU interrupt mask bits. The NMIEG bit in SYSCR can be used to select whether an interrupt is requested at a rising edge
or a falling edge on the NMI pin.
The vector number for NMI interrupt exception handling is 7.
IRQ7 to IRQ0 Interrupts: Interrupts IRQ7 to IRQ0 are requested by an input signal at pins IRQ7 to IRQ0. Interrupts
IRQ7 to IRQ0 have the following features:
• Using ISCR, it is possible to select whether an interrupt is generated by a low level, falling edge, rising edge, or both
edges, at pins IRQ7 to IRQ0.
• Enabling or disabling of interrupt requests IRQ7 to IRQ0 can be selected with IER.
• The interrupt priority level can be set with IPR.
• The status of interrupt requests IRQ7 to IRQ0 is indicated in ISR. ISR flags can be cleared to 0 by software.
A block diagram of interrupts IRQ7 to IRQ0 is shown in figure 5-2.
Cleared by reading IRQnF flag when IRQnF = 1, then writing 0 to IRQnF flag
When interrupt exception handling is executed when low-level detection is set
(IRQnSCB = IRQnSCA = 0) and IRQn input is high
When IRQn interrupt exception handling is executed when falling, rising, or both-edge
detection is set (IRQnSCB = 1 or IRQnSCA = 1)
When the DTC is activated by an IRQn interrupt, and the DISEL bit in MRB of the
DTC is cleared to 0
When IRQn input goes low when low-level detection is set (IRQnSCB = IRQnSCA =
0)
When a falling edge occurs in IRQn input when falling edge detection is set
(IRQnSCB = 0, IRQnSCA = 1)
When a rising edge occurs in IRQn input when rising edge detection is set
(IRQnSCB = 1, IRQnSCA = 0)
When a falling or rising edge occurs in IRQn input when both-edge detection is set
(IRQnSCB = IRQnSCA = 1)
(Initial value)
Rev.6.00 Oct.28.2004 page 87 of 1016
REJ09B0138-0600H
(n = 7 to 0)