Configuring pacemaker while 2kms away.

Person is travelling in driverless car

Possible within few couples of years.Possible within few couples of years.

Real Time Operating System Real Time Operating System (RTOS) and Embedded system are the (RTOS) and Embedded system are the major technologies that played a major major technologies that played a major role in making the above fairly tales role in making the above fairly tales come true. come true.

Defination of Embedded SystemDefination of Embedded System

An embedded system is one that has computer An embedded system is one that has computer hardware with software embedded in it as one of its hardware with software embedded in it as one of its most important component. most important component.

It is a It is a dedicateddedicated computer based system for an computer based system for an application or product.application or product.

As its software usually embeds in As its software usually embeds in ROMROM, it does not , it does not need secondary memories as in a computer.need secondary memories as in a computer.

CHARACTERISTICS OF EMBEDDED CHARACTERISTICS OF EMBEDDED SYSTEMSYSTEM

Single Functioned

T ightly C onstrained

R eal and R eactive

E M BE DDE D SYST E M

COMPONENTSCOMPONENTS

1.1. Main application SoftwareMain application Software:: Which Which may perform concurrently the series may perform concurrently the series of tasks or multiple tasks.of tasks or multiple tasks.

2.2. RTOS:RTOS: Supervises the application Supervises the application software and provides a mechanism software and provides a mechanism to let processor run process as per to let processor run process as per scheduling.scheduling.

3.3. Hardware:Hardware: Which includes Which includes following components.following components.

EMBEDDED SYSTEM EXAMPLE

PROCESSORPROCESSOR

A Processor is the heart of the A Processor is the heart of the embedded system. embedded system.

The Processor used in system can The Processor used in system can be one of the following:be one of the following:

• GPPGPP• ASSPASSP• Multiprocessor system using GPPsMultiprocessor system using GPPs

Important considerations when selecting a Important considerations when selecting a processor:processor:

•Instruction set Instruction set

•Maximum bits in an operand Maximum bits in an operand

•Clock frequency in MHz and processing speed in MIPS. Clock frequency in MHz and processing speed in MIPS.

  

EMBEDDED SOFTWAREEMBEDDED SOFTWARE

Typical structure of a simple Typical structure of a simple embedded Softwareembedded Software

looploop

read inputs/sensors;read inputs/sensors; compute response;compute response; generate outputs; generate outputs;

foreverforever

Design DecisionsDesign Decisions

          How to read inputs?How to read inputs?

          How often to read inputs?How often to read inputs?

          Which order to read the inputs?Which order to read the inputs?

          How to compute responses? How to compute responses?

          How to generate the responses?How to generate the responses?

   How often to generate?How often to generate?

The simplest approach-Round The simplest approach-Round Robin SchemeRobin Scheme

  looploop await tick; await tick; read S1; take_action(S1); read S1; take_action(S1); read S2; take_action(S2); read S2; take_action(S2); read S3; take_action(S3); read S3; take_action(S3);foreverforever

  Where, Tick is a time interruptWhere, Tick is a time interrupt

PROBLEMSPROBLEMS

        Processing speed decides the input rate!Processing speed decides the input rate!

        All sensors are treated identically All sensors are treated identically

        Fragile schemeFragile scheme

More sensors-more processing More sensors-more processing delay.delay.

    Fine for interactive system not for reactiveFine for interactive system not for reactive

systemsystem

The Most General SchemeThe Most General Scheme  

        Real-time OS (RTOS kernel)Real-time OS (RTOS kernel)

––manages the tasksmanages the tasks

––task communicationstask communications

––timer servicestimer services

––Schedules the tasks for execution using variousSchedules the tasks for execution using various

scheduling strategiesscheduling strategies

Problems with RTOSProblems with RTOS

      too much time and space overhead too much time and space overhead

      more complex designmore complex design

        deadlocksdeadlocks

Building predictable system is very Building predictable system is very challengingchallenging

Video games, Video terminals, multiple Video games, Video terminals, multiple levels of wireless networking, media levels of wireless networking, media caching and always on access to friends, caching and always on access to friends, news, entertainment, and data will keep news, entertainment, and data will keep our homes humming and trillions of MIPS our homes humming and trillions of MIPS flowing.flowing.

With terabytes and petabytes of storage, With terabytes and petabytes of storage, we will be able to store every book, every we will be able to store every book, every song, and every movie we have ever seen song, and every movie we have ever seen or ever want to see.or ever want to see.

Imagination is more Powerful than knowledge

-Albert Einstein