Contiki OS
Sharvil Patel, Michael Ray, Emily Rowland
1
Agenda
● Introduction to Contiki with History
● Components
● Applications
● Conclusion
2
Introduction
●
Real-time operating system
●
Specializes in Internet of Things (IoT)
https://github.com/lab11/atum
●
Low power oriented
●
Open-source (github.com/contiki-os)
○
●
Easy/Fast rapid development
○
●
Free in commercial and noncommercial applications
Developed in C
16 supported hardware platforms
http://www.ofrei.com/images/multi-draincell.jpg
3
Specifications
● Extremely lightweight
○ 10 kB of RAM
○ 30 kB of ROM
○ Fully functional system including GUI requires 30 kB of
RAM
■ Linux uses 1 MB!
4
History
● Created in 2002 by Adam Dunkels Ph.D.
○ Author of the uIP stack, Rime, protothreads
○ Founder of Thingsquare
● Now developed by a worldwide team
○ TI, Atmel, Cisco, Oxford University, SAP, etc, & you!
5
Applications
●
City sound monitoring
●
Street lights
●
Networked electrical power meters
●
Industrial monitoring
●
Remote house monitoring
●
Radiation monitoring
●
ATUM
6
OS components
● Processes
● Power awareness
● Protothreads
● Sleepy routers
● Communication stacks
● Cooja networking simulator
● Full IP networking
● Coffee - flash file system
● Memory allocation
● Rime stack
● Timers
● Watchdog
7
Processes
All programs in Contiki are processes
There are cooperative and preemptive contexts
https://github.com/contiki-os/contiki/wiki/Processes#The_Process_Thread
8
Protothreads
●
Mix of event-driven and multithreaded programming mechanisms
○
●
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Kernel invokes a process’ protothread in response to an event
Non-preemptive
○
Blocking event-handlers
○
Context switches only available on blocking operations
Stackless
○
●
http://dunkels.com/adam/pt/
Global variables are required for preserving variables across context switches
http://dunkels.com/adam/pt/expansion.html
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Protothreads (continued)
● Extremely lightweight
○ Overhead: 2 bytes (plus no stack)
● Portable
○ Can be used with/without an OS
https://github.com/contiki-os/contiki
○ Pure C code (macros)
10
Communication Stacks
Lightest
Rime
●
4 types
●
Rime
uIP
6LoWPAN
Heaviest
IPv4
http://dunkels.com/adam/dunkels07rime.
pdfhttps://github.com/adamdunkels/uip
●
○
Lightweight communication stack
○
When full IPv6 networking is overkill
○
Simple operations (single message sending)
○
Layered stack
uIP
○
TCP/IP stack
○
Meant for 8 bit and 16 bit devices
○
Very low RAM and overhead code
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Communication Stacks (continued)
●
Lightest
Rime
uIP
●
6LoWPAN
Heaviest
IPv4
IPv6 Ready certification
○
Developed by Cisco
○
Smallest IPv6 stack when it was created
6LoWPAN
○
IPv6 over Low power Wireless Personal Area Networks
○
Specializes in low power IPv6 communication
○
Allows send/receive over IEEE 802.15.4
■
http://www.ti.com/lsds/ti/wireless_connectivity/6lowpan/overview.page
http://www.tldp.org/HOWTO/Multicast-HOWTO-2.html
●
Same network as Zigbee
Capabilities: UDP, TCP, HTTP
12
Memory Allocation
● 3 types
○ memb memory block
■
Static memory struct
■
Most common
■
Lightweight
○ mmem managed memory,
○ malloc - standard C library
https://github.com/contiki-os/contiki/wiki/Memory-allocation
13
Timers
●
Uses: time elapsed, low power wake up, real time scheduling
○
Timer & STimer
■
○
Etimer
■
○
Timed events, repeated
Ctimer
■
○
Set, reset, check expiration manually, time remaining
Call a function when expired
Rtimer
■
For real-time tasks, preemptive
14
Power awareness
● Designed for small systems and to last on a pair of AA for
years
○ Dr. Kevin Fu
● Provides mechanisms for energy management and
system power consumption
● Uses timers to figure out where more energy was spent
15
Sleepy routers
● Power saving feature
● When devices are used as relay-nodes, or routers, in
wireless networks, Contiki allows these nodes to sleep
between packets
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Cooja networking simulator
●
Simulates Contiki nodes
●
Emulated node
○
●
Complete hardware emulation
Cooja node
○
Contiki code executed in the simulator
●
Java node
●
Uses:
https://github.com/contiki-os/contiki
○
Swarm intelligence
○
Indoor localization
http://www.contiki-os.org/start.html
17
Applications
18
Applications -- Koubachi Garden Sensor
Wireless, connected garden sensor
Data on water, temperature, and light
WiFi Connected
2 AA Batteries
http://www.koubachi.com
Push notifications and lookup database
19
Applications -- LIFX Color Changing Lights
Adjusts color, warmth, brightness and
intensity
Can be set to adjust via schedule
Connects with:
Apps, IFTTT, Nest Products, Samsung
SmartThings, Amazon Echo, and others
http://www.lifx.com
Contiki:
Wireless connectivity
20
Applications -- Life of a Badger
Sensor Collars with Microcontrollers
running Contiki
“Detailing badger behavior and locations
underground was impossible” - Dr.
Andrew Markham
Data sent wirelessly
http://www.bbc.com/news/t
echnology-13751740
Researchers using network maps of collar nodes
21
ATUM
●
Created here at U of M
○
●
●
Available in lab for our final projects
Project requirements:
○
“Connected” - network enabled
○
Low power
○
Responsive
○
Small
https://github.com/lab11/atum
Uses:
○
Timer (for PWM)
○
Protothreads
○
Interrupts
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Questions?
23
Resources
Getting Started
http://www.contiki-os.org
http://www.eecs.umich.edu/courses/eecs373/Lec/RTOS_short.pdf
https://github.com/contiki-os/contiki
Protothreads
http://dunkels.com/adam/pt/expansion.html
https://engineering.purdue.edu/dcsl/reading/2009/rpanta-protothread.pdf
Networking
https://github.com/adamdunkels/uip
http://dunkels.com/adam/dunkels07rime.pdf
http://www.tldp.org/HOWTO/Multicast-HOWTO-2.html
http://www.ti.com/lsds/ti/wireless_connectivity/6lowpan/overview.page
24
Bibliography
http://www.contiki-os.org
http://contiki-os.blogspot.com
http://www.thingsquare.com/customers/
http://www.lifx.com
http://www.eecs.umich.edu/courses/eecs373/Lec/RTOS_short.pdf
http://www.koubachi.com
http://www.bbc.com/news/technology-13751740
https://github.com/adamdunkels/uip
http://dunkels.com/adam/dunkels07rime.pdf
https://engineering.purdue.edu/dcsl/reading/2009/rpanta-protothread.pdf
25
mmem and malloc heap memory allocators
mmem is byte aligned, memcpy() or packed must be used
malloc is the same as defined in stdlib.h
https://github.com/contiki-os/contiki/wiki/Memory-allocation
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