Visible to Intel only — GUID: iga1401399660470
Ixiasoft
Visible to Intel only — GUID: iga1401399660470
Ixiasoft
38.1. Core Overview
The ability to process interrupt events quickly and to handle large numbers of interrupts can be critical to many embedded systems. The Vectored Interrupt Controller (VIC) is designed to address these requirements. The VIC can provide interrupt performance four to five times better than the Nios® II processor’s default internal interrupt controller (IIC). The VIC also allows expansion to a virtually unlimited number of interrupts, through daisy chaining.
The vectored interrupt controller (VIC) core serves the following main purposes:
- Provides an interface to the interrupts in your system
- Reduces interrupt overhead
- Manages large numbers of interrupts
The VIC offers high-performance, low-latency interrupt handling. The VIC prioritizes interrupts in hardware and outputs information about the highest-priority pending interrupt. When external interrupts occur in a system containing a VIC, the VIC determines the highest priority interrupt, determines the source that is requesting service, computes the requested handler address (RHA), and provides information, including the RHA, to the processor.
The VIC core contains the following interfaces:
- Up to 32 interrupt input ports per VIC core
- One Avalon® Memory-Mapped ( Avalon® -MM) agent interface to access the internal control status registers (CSR)
- One Avalon® Streaming ( Avalon® -ST) interface output interface to pass information about the selected interrupt
- One optional Avalon® -ST interface input interface to receive the Avalon® -ST output in systems with daisy-chained VICs
The Sample System Layout Figure below outlines the basic layout of a system containing two VIC components.
The VIC core provides the following features:
To use the VIC, the processor in your system needs to have a matching Avalon® -ST interface to accept the interrupt information, such as the Nios® II processor's external interrupt controller interface.
The characteristics of each interrupt port are configured via the Avalon® -MM agent interface. When you need more than 32 interrupt ports, you can daisy chain multiple VICs together.
- Separate programmable requested interrupt level (RIL) for each interrupt
- Separate programmable requested register set (RRS) for each interrupt, to tell the interrupt handler which processor register set to use
- Separate programmable requested non-maskable interrupt (RNMI) flag for each interrupt, to control whether each interrupt is maskable or non-maskable
- Software-controlled priority arbitration scheme
The VIC core is Platform Designer ready and integrates easily into any Platform Designer generated system. For the Nios® II processor, Intel provides Hardware Abstraction Layer (HAL) driver routines for the VIC core. Refer to to Intel FPGA HAL Software Programming Model section for HAL support details.