Digital Signal Processing Reference
In-Depth Information
18.5 Implementing the µClinux on the DE Board
To illustrate the benefits of operating systems in embedded systems, the next
few sections will step the reader through the design and implementation of a
Nios II system running µClinux on a DE board.
There are two main distributions of µClinux that work on the Nios II processor.
The first distribution is controlled and released by Microtronix
(www.microtronix.com). They provided the original kernel code modifications
to support the Nios II processor. Their distribution also integrates into the Nios
II IDE design environment. However, as of the publication date of this topic,
Microtronix's latest version, release 1.4, does not work with Nios II 7.1.
Release 1.4 was originally designed for Nios II 5.0 and there are reports of
users on the Nios Community Forum (www.niosforum.com) successfully using
it in Nios II 6.0. Microtronix distributions are freely available for download on
the Nios Community Forum under Downloads. (To view the Downloads
section, you must be a registered user of the forum's website.) The primary
advantage of this distribution is its tight integration into the Nios II IDE and
build environment; however, Microtronix releases tend to lag behind Altera's
software releases.
A second distribution of µClinux has been developed and released on the
http://nioswiki.jot.com/WikiHome/ website by a group of developers who
frequent the Nios Community Forum. These developers took Microtronix's
distribution and updated it with support for the latest Linux kernel release,
additional device drivers, and a larger collection of libraries and user
applications. Instead of integrating µClinux developing and compilation into
the Nios II IDE, this distribution includes uClinux-dist, a Linux-based build
environment. You must have access to a computer running the Linux operating
system to install, customize, and build this distribution of the µClinux kernel.
The remainder of this chapter will focus on this second distribution of µClinux,
which will be referred to as µClinux for Nios II. While full details of the
development of a custom µClinux kernel for the DE boards is beyond the scope
of this topic, a pre-built kernel is provided for the reader's use and exploration.
Readers who want to modify the kernel image should consult the
http://nioswiki.jot.com/WikiHome/ website, which includes the uClinux-dist
distribution as well as the necessary patches for Nios II freely available for
download. In addition, this website has a number of tutorials and application
notes available that step through the customization of various devices and
services in µClinux (including information specific to the DE2 board).
Additional
help
is
available
in
the
Nios
Community
Forum
(www.niosforum.com).
18.6 Hardware Design for µClinux Support
When compiling µClinux for Nios II, the Nios II peripheral template file (.ptf)
for the specific Nios II processor configuration being used must be provided.
The .ptf file contains the processor and peripheral details for a given Nios II
configuration including the IRQ mappings, memory address ranges for the
