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How to Code on TinyOS

How to Code on TinyOS. Xufei Mao Advisor: Dr. Xiang-yang Li CS Dept. IIT. Outlines. What is TinyOS? Hardware & Software NesC A simple example Conclusion. So why do we need a new OS?. Traditional OS. Huge ! Multi-threaded architecture =>large memory I/O model

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How to Code on TinyOS

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  1. How to Code on TinyOS Xufei Mao Advisor: Dr. Xiang-yang Li CS Dept. IIT

  2. Outlines • What is TinyOS? • Hardware & Software • NesC • A simple example • Conclusion

  3. So why do we need a new OS?

  4. Traditional OS Huge ! Multi-threaded architecture =>large memory I/O model Kernel and user space separation Typically no energy constraints Ample available resources

  5. Sensor Hardware Constraints • Lower Power • Limited memory • Slow CPU • Size (Small) • Limited hardware parallelisms • Communication using radio • Low-bandwidth • Short range

  6. Desired OS Properties • Small memory footprint • Efficient in power and computation • Communication is fundamental • Real-time • Support diverse application design

  7. TinyOS Solution • Concurrency: uses event-driven architecture • Modularity • Application composed of components • OS + Application compiles into single executable • Communication • Uses event/command model • FIFO and non pre-emptive scheduling • No kernel/application boundary

  8. The Hardware

  9. Software • TinyOS (Platform) • Coding language • NesC (Network Embedded System C)

  10. TinyOS Memory Model • STATIC memory allocation! • No heap (malloc) • No function pointers • No dynamic, run-time allocation • Global variables • Available on a per-frame basis • Conserve memory • Use pointers • Local variables • Saved on the stack • Declared within a method

  11. TinyOS & nesC Concepts • New Language: nesC. Basic unit of code = Component • Component • Process Commands • Throws Events • Has a Frame for storing local state • Uses Tasks for concurrency • Components provide interfaces • Used by other components to communicate with this component

  12. Components • Two type of components • Module • component written with code • Configuration • components wired together

  13. Components

  14. TinyOS Application(Sample)

  15. Commands/Events/Tasks • Commands • Should be non-blocking i.e. take parameters start the processing and return to app; • postpone time-consuming work by posting a task • Can call commands on other components • Events • Can call commands, signal other events, post tasks but cannot be signal-ed by commands • Pre-empt tasks, not vice-versa • Tasks • FIFO scheduling • Non pre-emptable by other task, pre-emtable by events • Used to perform computationally intensive work • Can be posted by commands and/or events

  16. nesC • Naming conventions • nesC files extension: .nc • Clock.nc : either an interface (or a configuration) • ClockC.nc : a configuration • ClockM.nc : a module

  17. nesC Keywords

  18. nesC Keywords -implementation

  19. Interfaces

  20. Modules • Implement one or more interfaces • Can use one or more other interfaces

  21. Modules (Sample)

  22. Configurations • Two components are linked together in nesC by wiring them • Interfaces on user component are wired to the same interface on the provider component • 3 wiring statements in nesC: • endpoint1 = endpoint2 • endpoint1 -> endpoint2 • endpoint1 <- endpoint2 (equivalent: endpoint2 -> endpoint1)

  23. Configurations (Sample)

  24. nesC Wiring Syntax

  25. Compile & Run • Compiler processes nesC files converting them into a gigantic C file • Has both your application & the relevant OS components you are using • Then platform specific compiler compiles this C file • Becomes a single executable • Loader installs the code onto the Mote (Mica2, Telos, etc.)

  26. Simple Example 1 • Blink Application • Blink.nc configuration

  27. Simple Example 1 • Blink Application • BlinkM.nc module

  28. Simple Example 2 • Communication between two sensors • Environment : Xubuntu + TinyOS 2.0 • Hardware: TelosB sensors

  29. Resources • Gaurav’s TinyOS-1.x installation howto: • http://www.cs.umass.edu/~gmathur/misc/tinyos_setup.htm • Tinyos-2.x installation howto (straightforward): • http://www.tinyos.net/tinyos-2.x/doc/html/install-tinyos.html • The official TinyOS tutorial (pretty good): • http://www.tinyos.net/tinyos-1.x/doc/tutorial/ • The offical TinyOS-2.x tutorial (very good): • http://www.tinyos.net/tinyos-2.x/doc/html/tutorial/index.html • nesC: http://nescc.sourceforge.net/

  30. Resources • Other Docs: • nesC paper: http://none.cs.umass.edu/~gmathur/tinyos/nesc-pldi-2003.pdf • nesC manual: http://none.cs.umass.edu/~gmathur/tinyos/nesc-ref.pdf • TinyOS abstractions: http://none.cs.umass.edu/~gmathur/tinyos/tinyosnsdi04.pdf

  31. Reference • TinyOS Tutorial by Jeremy Gummeson, Sensors Lab, UMass-Amherst • TinyOS Programming by Philip Levis • nesC paper: http://none.cs.umass.edu/~gmathur/tinyos/nesc-pldi-2003.pdf

  32. Conclusion

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