The Contiki Operating System was developed by Adam Dunkels of SICS in 2003. It is named after Thor Heyerdahl's Kon-Tiki raft. Contiki is commonly used as an OS for networks of embedded systems and by hobbyists for older systems. It has minimal requirements for memory and supports features like an event-driven kernel, TCP/IP networking, dynamic program loading, and protothreads for multitasking. These features allow it to run on small microcontrollers and be used for networked embedded applications.

1. The Contiki Operating System
Bigali Amanzhayev
IA-2002

2. History
 Developed by Adam Dunkels of SICS
 Also developed protothreads and μIP
 First released on March 10, 2003
 Named after Thor Heyerdahl's famous
Kon-Tiki raft
 “Contiki runs on tiny and prehistoric
computers, yet is able to do much of what
we expect from large and modern
computers.”

3. Who uses it?
 Most common application is as an OS
for Networks of Embedded Systems
 Hobbyists use it as an OS for older
and smaller systems
 Ports for Apple II, Atari, Gameboy, NES,
Commodore 64 and 128
 Screen captures at
http://www.sics.se/~adam/contiki/ports/i
ndex.html

4. Features
 Minimalist Event Driven Kernel, even
runs on 8-bit Microcontrollers
 TCP/IP Stack Support
 Dynamic Loading and Unloading of
Programs
 Small Memory Requirements
 Optional Preemptive Multithreading
through Protothreads

5. Event Driven Kernel
 Kernel is event based making it a
real time OS
 An event triggers the kernel to call the
corresponding event handler
 Functions very similar to TinyOS
 Has its drawbacks, i.e. long running
computations

6. TCP/IP Stack Support
 Implements Dunkels’s own TCP/IP
stack called μIP
 Memory Requirements
 Kilobytes of Program Code
 Hundreds of bytes of RAM
 Allows to connect to networks using
SLIP (Serial Line IP)

7. Dynamic Program Loading
 The Core Code and Program Code
are kept separate in ROM.
 Program Code loaded at runtime.
 Program code can be loaded from
ROM or RAM
 Allows for “Over the Air
Programming” for networks of
sensors

8. Small Memory Requirements
 The base system, providing
multitasking and TCP/IP networking,
can be compiled in about 32 KB
 Smallest system to date uses about
2000 bytes of RAM
 Jack Ganssle praised Contiki for its low
memory usage in his Embedded Muse
newsletter, #113

9. Protothreads
 Implemented as an additional library
on top of the event based kernel
 Stackless, lightweight thread
comprised of a single C function using
2 bytes of RAM to record its state
 Adds a layer of abstraction to the
state-machine event based code
usually written, to create a sequential
flow of program code.

10. Event-driven
 Event-driven
(TinyOS)
 Processes do not run
without events
 Event occurs: kernel
invokes event
handler
 Event handler runs
to completion
(explicit return;)
Kernel
Handler
Handler
Handler
Handler

11. Contiki Programs
 Contiki Tool-kit (CTK) GUI
 Virtual Network Computing (VNC) Server
 A Web Server
 A Web Browser
 A command line shell.
 A telnet server.
 An IRC client.
 An FTP client.
 A disk directory file reader.
 A file and disk image downloader utility.
 A simple desktop calculator.

12. End
 Works Cited
 Slides 10 and 11 Taken from
Adam Dunkles Presentation
Contiki – a Lightweight and Flexible
Operating System for Tiny
Networked Sensors
found at
http://www.sics.se/~adam/slides/contiki-
emnets.ppt