Control, data acquisition and embedded Linux

The Linux Lab Project

Clearing house (mailing list, web site and FTP site) for developers of:

• Data acquisition
• Process control
• Device drivers
• Laboratory automation
• Data analysis

Some important contributions include:

• GPIB drivers
• COMEDI: a standard driver interface
• CAN and I2C support
• A/D, DSP, Bus drivers

Real Time Linux

RTLinux:

• A small hard real-time kernel that sits between Linux & the hardware
• Runs Linux as one task of the real-time kernel
• Latency < 15 microseconds (normal Linux > 20 milliseconds)
• Real-time tasks controlled via devices or shared memory
• Allows the control of data acquisition/control boards, robots, etc.
• Competitive alternative to non-free real-time operating systems (eg. QNX).

Used extensively by university projects, NASA, Jim Henson Creature Shop...

Embedded Linux

• Linux is being embedded in a wide range of products from data loggers to dedicated network routers
• Excellent support for a wide range of low-cost embedded platforms, including the 68000, StrongARM, Motorola VME, ELKS: 80x86 (x < 3), Motorola ColdFire and PalmPilot
• Linux runs on PC104 boards - industry standard for miniaturised motherboards and expansion cards
• Support now available for IDE Flash drives and other solid-state devices
• No licence and no royalty fees
• Linux is well suited for some embedded tasks as it offers full source, it is easily customised, has full networking capabilities, support for devices such as ROM filesystems and has real-time extensions
• Support for a wide variety of user interfaces: none, custom-designed, text consoles, or GUI (via SVGAlib or X-Windows)
• Linux is not well suited for some embedded tasks as it requires at least 2 - 4 MB RAM unless you use an early kernel version
• The common Linux distributions are often not suitable for embedded systems, but there are some small distributions now available, such as the appropriately named Small Linux and the Linux Router Project
• There is a useful HOWTO on embedding Linux

One example of a small embedded Linux system - the world's smallest web server:

LabView for Linux

• Port of LabView FDS v5.1
• Only available for x86 Linux
• Requires Linux 2.0+ and glibc 2 (needs POSIX threads)
• LabView applications can be ported from other LabView platforms as long as the hardware is supported under Linux
• National Instruments only provide GPIB drivers
• Drivers for any other card/device have to be sourced from elsewhere
• An academic version is available

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Updated: 20 June 1999