User guide

Features and Terms Reference

Hardware Abstraction Layer (HAL)

The Nios II hardware abstraction layer (HAL) runtime library is a lightweight runtime

environment that provides a simple device driver interface for programs to communicate with

the underlying hardware. The HAL application program interface (API) is integrated with the

ANSI C standard library. The HAL API allows you to access devices and files using familiar C

library functions, such as printf(), fopen(), fwrite(), etc.

The HAL serves as a board-support package for Nios II processor systems, providing a

consistent interface to the peripherals in your embedded systems. The Nios II integrated

development environment (IDE) incorporates the HAL for you automatically. The Nios II IDE

generates a custom HAL system library to match the hardware configuration. Changes in the

hardware configuration automatically propagate to the HAL device driver configuration,

preventing bugs that might otherwise appear due to subtle changes in the underlying

hardware.