Nios II Classic Software Developer’s Handbook

ID 683282
Date 5/14/2015
Public
Document Table of Contents

8.1.2.1. Internal Interrupt Concepts

With the IIC, Nios II exception handling is implemented in classic RISC fashion. All exception types, including hardware interrupts, are dispatched through a single top-level exception funnel. This means that all exceptions (hardware and software) are handled by code residing at a single location, the exception address.

The IIC is a simple, nonvectored hardware interrupt controller. Upon receipt of an interrupt request, the IIC transfers control to the general exception address. The hardware indicates which IRQ is currently asserted, and allows software to mask individual interrupts.

With the IIC, the HAL interrupt funnel identifies the hardware interrupt cause in software, and dispatches the registered ISR.

The IIC is available in all revisions of the Nios II processor.