1 / 22

LAB (Embedded System): Programming on Sensor Networks

LAB (Embedded System): Programming on Sensor Networks. TinyOS and NesC. What is TinyOS?. NesC A superset of C Main feature: Component based programming with separation of declaration and definition TinyOS An event-driven operating system Developed using NesC

annelise
Télécharger la présentation

LAB (Embedded System): Programming on Sensor Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. LAB (Embedded System): Programming on Sensor Networks TinyOS and NesC

  2. What is TinyOS? • NesC • A superset of C • Main feature: • Component based programming with separation of declaration and definition • TinyOS • An event-driven operating system • Developed using NesC • Support for many types of motes • At least 15 Motes types are supported by NesC/TinyOS (source: SNM)

  3. NesC Concepts • Component • Module • Configuration • Interface • Command (Sync Vs Async Commands) • Event • Split-Phase • Task

  4. Let’s start simple • Goal: write an anti-theft device. • Two parts: • Detecting theft. • Assume: thieves put the motes in their pockets. • So, a “dark” mote is a stolen mote. • Theft detection algorithm: every N ms check if light sensor is below some threshold • Reporting theft. • Assume: bright flashing lights deter thieves. • Theft reporting algorithm: light the red LED for a little while! • What we’ll see • Basic components, interfaces, wiring • Essential system interfaces for startup, timing, sensor sampling

  5. Components • A component is based on C dialect • A component is similar to Java object • It provides encapsulated state and couple state with functionality • A component is not really a Java object • No inheritance and usually Singleton • Components have only private variables • Only functions could be used to pass the variables between components • Two types of components • Modules • Configuration

  6. Data Type declaration uint8_t int8_t uint16_t int16_t bool Components #include … moduleAntiTheftC { uses interface ….; } implementation { int8_t var1; } configuration AntiTheftAppC { } implementation { components AntiTheftC , ..; ….. }

  7. Module & Interface • Module has implementation of functions • It uses pure local namespace • Component has to declare function it uses and provides • NesC Interface is very Similar to Java Interface • Declaration of functions

  8. Interface interface Boot { /* Signaled when OS booted */ event void booted(); } interface Timer<tag> { command void startOneShot(uint32_t period); command void startPeriodic(uint32_t period); event void fired(); } interface Read<val_t> { command error_t read(); event void readDone(error_t ok, val_t val); }

  9. interface Boot { /* Signaled when OS booted */ event void booted(); } interface Timer<tag> { command void startOneShot(uint32_t period); command void startPeriodic(uint32_t period); event void fired(); } Module & Interface module AntiTheftC { uses interface Boot; uses interface Timer<TMilli> as Check; uses interface Read<uint16_t>; } implementation { event void Boot.booted() { call Check.startPeriodic(1000); } event void Check.fired() { call Read.read(); } event void Read.readDone(error_t ok, uint16_t val) { if (ok == SUCCESS && val < 200) theftLed(); } } Programs are built out of named components A component provides and uses interfaces Interfaces contain commands and events, which are just functions A module is a component implemented in C

  10. Module & Interface Interfaces specify the interaction between two components, the provider and the user. This interaction is just a function call. commands are calls from user to provider events are calls from provider to user module AntiTheftC { uses interface Boot; uses interface Timer<TMilli> as Check; uses interface Read<uint16_t>; } implementation { event void Boot.booted() { call Check.startPeriodic(1000); } event void Check.fired() { call Read.read(); } event void Read.readDone(error_t ok, uint16_t val) { if (ok == SUCCESS && val < 200) theftLed(); } } interface Boot { /* Signaled when OS booted */ event void booted(); } interface Timer<tag> { command void startOneShot(uint32_t period); command void startPeriodic(uint32_t period); event void fired(); }

  11. Module & Interface module AntiTheftC { uses interface Boot; uses interface Timer<TMilli> as Check; uses interface Read<uint16_t>; } implementation { event void Boot.booted() { call Check.startPeriodic(1000); } event void Check.fired() { call Read.read(); } event void Read.readDone(error_t ok, uint16_t val) { if (ok == SUCCESS && val < 200) theftLed(); } } • All long-running operations are split-phase: • A command starts the op: read • An event signals op completion: readDone interface Read<val_t> { command error_t read(); event void readDone(error_t ok, val_t val); }

  12. Module & Interface module AntiTheftC { uses interface Boot; uses interface Timer<TMilli> as Check; uses interface Read<uint16_t>; } implementation { event void Boot.booted() { call Check.startPeriodic(1000); } event void Check.fired() { call Read.read(); } event void Read.readDone( error_t ok, uint16_t val) { if (ok == SUCCESS && val < 200) theftLed(); } } • All long-running operations are split-phase: • A command starts the op: read • An event signals op completion: readDone • Errors are signalled using the error_t type, typically • Commands only allow one outstanding request • Events report any problems occurring in the op interface Read<val_t> { command error_t read(); event void readDone(error_t ok, val_t val); }

  13. Module & Interface module TimerMilliC{ provides interface Timer<TMilli> as TimerMilli[uint8_t num]; } implementation { ..... command void TimerMilli.startPeriodic[uint8_t id]( uint32_t dt ) { ... } command void TimerMilli.startOneShot[uint8_t id]( uint32_t dt ) { .... } void tossim_timer_handle(sim_event_t* evt) { .. signal TimerMilli.fired[id](); } }

  14. Configuration • Recall: Components have two types • Module • Configuration • Configuration • Wire components together • Has two operations • user -> provider (or provider <- ser) • = (between two providers mostly) • To export interface

  15. Configurations generic configuration TimerMilliC() { provides interface Timer<TMilli>; } implementation { ... } configuration AntiTheftAppC { } implementation { components AntiTheftC, MainC, LedsC; AntiTheftC.Boot -> MainC.Boot; AntiTheftC.Leds -> LedsC; components new TimerMilliC() as MyTimer; AntiTheftC.Check -> MyTimer; components new PhotoC(); AntiTheftC.Read -> PhotoC; } generic configuration PhotoC() { provides interface Read; } implementation { ... } A configuration is a component built out of other components. It wires “used” to “provided” interfaces. It can instantiate generic components It can itself provide and use interfaces

  16. Split-Phase • Split-phase in hardware then split-phase in software • Two phase • Downcall : Command – start the operation • Upcall : Event – operation has been completed

  17. Command & Event • All commands are implemented by all providers of an interface • All events are implemented by all users of an interface • Example Interface Send { command error_t send(message_t* msg, uint8_t len); event void sendDone(message_t* msg, error_t error); } module SendC { uses interface Send; uses interface Boot; } Implementation { event void Boot.booted() { call Send.send(NULL, 0); } event void sendDone(message_t* msg, error_t error) { //do nothing } }

  18. Task • Task • Are deferred procedure call • Event are usually signaled by posting a task • Task are strictly local to a module • No parameters • No return type • No defined in any interface • Each task is non-preemptive and atomic with respect to other tasks • A task can post itself

  19. Async Vs Sync command • Async are preemptable commands • Unlike task Async commands are not atomic with respect to other commands • Async command cannot call a Sync command • Can call other Async commands • Can post task which may call a Sync command • Sync commands calls are blocking like normal function call

  20. TinyOS and NesC limitations • Thread Vs event driven • TinyOS is event-driven and not a thread base OS • Threads have better response time • Event drive OS has less memory requirements • Event driven model drawbacks: • requires manual configuration • Manual state handling • Difficult to change code without changing already written state handlers • All Events have to be implemented by a user of an interface • Even if user of a interface is not interested in many of them

  21. Exercise 1 • Take a random number in every 1000ms • If it is even then toggle the led0 • If there are two consecutive even numbers, toggle the led1 • If there are two consecutive odd numbers, toggle the led2 module XYZ{ uses interface Random; } implementation { } configuration XYZC{} implementation { ….. components RandomLfsrC; }

  22. Exercise 2 • Take a random number in every 1000ms • NODE 1: If the number is even, sends it to NODE 2 then toggle the led0, NODE 2 receives the packet check the number is even and toggle led 0 • NODE 2: If the number is odd, sends it to NODE 1 then toggle the led2, NODE 1 receives the packet check the number is odd and toggle led 2

More Related