embedded linux

Ascendco Scientific, Inc.www.ascendco.com page 1

Embedded LinuxUsing Pee Wee Linux

Presented by

Randy Torgerson

Ascendco Scientific, Incfor

Linux System Administrators

June 3, 2002


Who is Ascendco Scientific, Inc?We are engineering consultants that design hardware and software for embedded systems products. Our expertise is in x86, PowerPC, ColdFire, ARM, and microcontroller systems running Linux, VxWorks, or custom software.


Embedded Linux What is an Embedded System? An Embedded System is any computer system

or computing device that performs a dedicated function or is designed for use with a specific embedded software application Examples: ATM, Microwave, Tivo

May or may not have an operating system Designed to run specific tasks Generally has just enough resources for the

tasks that are to be run


Embedded Linux Definitions

RTOS Real Time Operating System

Deterministic The ability to respond to an event within a specific amount of time

Preemptible The ability to have a process interrupted by a higher priority process

Task Scheduler The part of the kernel that determines what other processes will run and when


Embedded Linux RTOS

Hard Real Time Deterministic

Missed events can have catastrophic results

Soft Real Time Not deterministic

Can tolerate missed events

Real Fast High throughput

Linux is not Real Time . . . yet


Embedded Linux Linux is not Real Time

Kernel is not preemptible

Task scheduling is not priority based

RTLinux and RTAI runs Linux as a process under a proprietary real time kernel

Hardhat Linux uses the preemptible Kernel

Preemptible Kernel maybe integrated into Kernel release 2.6


Embedded Linux Embedded Linux Toolkits

Pee Wee Linux

HardHat Linux from Monta Vista

BlueCat Linux from Lynux Works

The Embedded Debian Project

Embedded DevKit from Red Hat

Linux Router Project


Home Automation Project Objectives

Lighting Controller using X10 powerline interface

AC Energy Monitoring using custom energy monitoring board

Security Camera

Web Interface for remote access and control

Learn Embedded Linux


Home Automation Project Why LxSA and Embedded Linux

Most problems have been with configuring the development station and not on the client

With Embedded Linux you will get a good understanding of the internals of Linux

Working on the small Linux system allows for in-depth understanding of the boot process and file system


Home Automation Project Development System

Dell 866 MHz Pentium III with 128MB

Redhat Linux 7.1 with KDE desktop

USB CompactFlash Adapter Allows for quick update of target file system


Home Automation Project ABIA Tech FB2310 AllInOne

PC/104 single board computer. 386SX, 40MHz, 4MB RAM

64MB CompactFlash Disk on a IDE to CompactFlash adapter board

Two Serial Ports, Parallel Port 10baseT Ethernet Sockets for 1.5MB Flash Video is provided by an

Orchid Prodesigner IIS ISA card and a PC/104 to ISA Adapter


Home Automation Project Target Software

PeeWee Linux with Kernel 2.2.17

The web server is thttp

The current image is 3.9MB and will be reduced as unneeded tools are removed

The Kernel will also be compiled to run in place and put in the 1.5MB Flash sockets


Home Automation Project Problems

gcc 2.96 with Redhat 7.1 cannot compile the 2.2 kernel, must use kgcc

Must use the compatibility libraries: compatglibc, compategcs, compatlibs, compatlibstdc and run script before compiling

Path on development system get corrupted during boot and prevents proper compiles PATH=/usr/kerberos/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/local/bi

n:/home/randy/bin _=/usr/bin/env


Pee Wee Linux Based on Redhat 6.2

Kernel 2.2.1713

Can run on Redhat 7.1 or other systems with a little work.

Actively maintained and has an email group

i386, i486, Pentium I, II, and III targets only.

Uses Ncurses character interface.


Pee Wee Linux Development Process

Write down what you want to accomplish

Select the Embedded Linux Tool kit that fits your needs

Install the tool kit on your development system

Proof the build process with a minimal project

Down load to the target and test

Add features and test


Pee Wee Linux Project Development Process

Create custom kernel package

Configure custom file system

Extract the file system for project

Configure target hardware

Load file system onto target

Test features on target


Pee Wee LinuxSystem Menu


Pee Wee Linux Project Creation

Start with one of the examples

Use precompiled or custom kernel

Custom Kernel Run Menuconfig and select the options as necessary

Get the Linux Kernel HOWTO

Compile the kernel

Create the custom kernel package


Pee Wee LinuxConfigure Files Menu


Pee Wee Linux Packages

Select the packages to build into the system Kernel or custom kernel

Networking

Shells

System Administration

X Windows

System files


Pee Wee LinuxConfiguring Project File System


Pee Wee Linux Extract the file system for the target

Can include custom files

Custom files have preference over default files for the same target location and file name


Pee Wee LinuxResults from Extract File System for Project


Pee Wee Linux

Extract the file system to target

Can be a hard disk or CompactFlash

For small systems can be floppy disk

CompactFlash is the easiest to use

Easy to experiment to find what works best


Pee Wee LinuxConfigure Target Hardware


Embedded Linux What have I learned

4MB RAM is barely enough memory for Linux with networking

8 or 16 MB RAM would allow for the less efficient, memory wise, 2.4 kernel

Network boot would speed up development but CompactFlash is very easy to set up and use

All the tool kits have some rough edges


Embedded Linux Resources

Embedded Linux by John Lombardo

New Riders Publishing

Good introduction to Embedded Linux, doesn't make a lot of assumptions

Projects are too simplistic



Embedded Linux: Hardware, Software, and Interfacing by Craig Hollabaugh

Assumes you know what you are doing

Many gross errors that makes all material suspect



Practical Linux Programming: Device Drivers, Embedded systems, and the Internetby Ashfaq A. Khan

Includes CDROM and runs under Redhat 7.1 or higher



Embedded Linux Journal

Interesting articles

Will no longer be published as a standalone magazine. Will be a section in Linux Journal

Articles are available at embedded.linuxjournal.com



Web sites

linuxdevices.com

embedded.linuxjournal.com

google.com/linux

embedded.adis.on.ca for Pee Wee Linux

embedded linux

Documents

embedded linux linux

wee linux hardhat linux

target ascendco scientific

internals of linux

small linux system

test ascendco scientific

usrbinenv ascendco scientific

mb redhat linux