1. The Contiki Operating System
Jack Nosek

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

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

11. Contiki: implementing threads on top of an event-based kernel

12. 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.

13. 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