How to Code on TinyOS

Xufei Mao Xufei Mao Advisor: Dr. Xiang-yang LiAdvisor: Dr. Xiang-yang Li

CS Dept. IITCS Dept. IIT

Outlines

What is TinyOS?What is TinyOS? Hardware & SoftwareHardware & Software NesCNesC A simple exampleA simple example ConclusionConclusion

So why do we need a new OS?

Traditional OS

Huge !Multi-threaded architecture =>large memoryI/O modelKernel and user space separationTypically no energy constraintsAmple available resources

Sensor Hardware Constraints Lower Power Limited memory Slow CPU Size (Small) Limited hardware parallelisms Communication using radio

Low-bandwidth Short range

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

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

The Hardware

Software

TinyOS (Platform) TinyOS (Platform) Coding languageCoding language

NesC (Network Embedded System C)NesC (Network Embedded System C)

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

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

Components

Two type of componentsTwo type of components ModuleModule

component written with codecomponent written with code ConfigurationConfiguration

components wired togethercomponents wired together

Components

TinyOS Application (Sample)

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

nesC Naming conventions

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

nesC Keywords

nesC Keywords -implementation

Interfaces

Modules Implement one or more interfaces Can use one or more other interfaces

Modules (Sample)

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)

Configurations (Sample)

nesC Wiring Syntax

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.)

Simple Example 1

Blink ApplicationBlink Application Blink.nc configuration Blink.nc configuration

Simple Example 1

Blink ApplicationBlink Application BlinkM.nc moduleBlinkM.nc module

Simple Example 2

Communication between two sensorsCommunication between two sensors Environment : Xubuntu + TinyOS 2.0Environment : Xubuntu + TinyOS 2.0 Hardware: TelosB sensorsHardware: TelosB sensors

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/

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

Reference TinyOS TutorialTinyOS Tutorial by by Jeremy Gummeson, Sensors Lab,

UMass-Amherst TinyOS Programming by Philip Levis nesC paper: http://none.cs.umass.edu/~gmat

hur/tinyos/nesc-pldi-2003.pdf

Conclusion