Embedded System Design and Development

Introduction to Embedded System

Embedded SystemsEmbedded Systems

Embedded - Fix firmly in a surrounding areas

System - Set of connected things

Embedded systemsEmbedded systems

Embedded System is a combination of hardware and software used to achieve a single specific task.

Embedded systems are computer systems that monitor, respond to, or control an external environment.

Environment connected to systems through sensors , actuators and other I/O interfaces.

Embedded system must meet timing & other constraints imposed on it by environment

The EssenceAn embedded system is a microcontroller-based, software driven, reliable, real-time control system, autonomous, or human or network interactive, operating on diverse physical variables and in diverse environments, and sold into a competitive and cost conscious market.

What an Embedded system is not ?What an Embedded system is not ?

Not a computer system that is used primarily for processing

Not a software system on PC or Unix

Not a traditional business or scientific application

ENVIRONMENT CONNECTEDENVIRONMENT CONNECTED

Applications Applications

CharacteristicsCharacteristics In-built Intelligence. Immediate control of hardware. Uses dedicated software. Performs a specific function. Their work is subject to deadlines. Respond to external events. Timeliness, Robustness/Safety Processing power and Memory limitations Program is stored in nonvolatile memory such that it can be

executed on power up. Mostly interactive with I/O devices in the real world. Cope with all unusual conditions without human intervention

CategoriesCategories

EMBEDDED SYSTEMS

MICROCONTROLLERS DSP ASIC

ClassificationClassification

Real Time Systems

RTS is one which has to respond to events within a specified deadline

– A right answer after the dead line is a wrong answer RTS are classified in to three categories

Hard Real Time Systems Soft Real Time System Firm Real Time System

Hard Real Time Systems "Hard" real-time systems have very narrow response time Example: Nuclear power system , Cardiac pacemaker.

Soft Real Time System "Soft" real-time systems have reduced constrains on

"lateness" but still must operate very quickly and repeatable. Example: Railway reservation system – takes a few extra

seconds the data remains valid.

Firm Real Time System Firm deadliness are a combination of both hard and soft

timeliness requirements.

FailureFailure Safety Critical The failure of the system may lead to disastrous/ damage

to safety of the system/environment. Example: Control Systems in Nuclear applications, Flight Control Systems, Life Monitoring Systems, etc.

Mission Critical The failure may lead to non-accomplishment of the mission

and the time spends will be wasted .The system had to run again to complete the missions. Example: Test Equipment

Non-critical The failure does not have much impact. Example: Washing

Machines, etc.

How are embedded systems different How are embedded systems different than traditional software ?than traditional software ?

Responding to sensors (was this button pushed?)

Turning on actuators ( Turn on power to the boiler)

Real - Time (respond to temperature change within 3 seconds)

Differences between ES and traditional Differences between ES and traditional software developmentsoftware development

Not dealing with only sequential code

Routine can stop at completion or in response to an external event

Many parts of system might be running concurrently

Safety- critical component of many systems

Embedded System RequirementsEmbedded System Requirements

Types of requirements imposed by embedded applications:

R1 Functional Requirements

R2 Temporal Requirements

R3 Dependability requirements

R1 Functional RequirementsR1 Functional Requirements

Data Collection– Sensor requirements– Signal conditioning– Alarm monitoring

Direct Digital Control– Actuators

Man-Machine Interaction– informs the operator of the current state of the controlled

object– Assists the operator in controlling the system

R2 Temporal RequirementsR2 Temporal Requirements

Tasks may have deadlinesMinimal latency jitterMinimal error detection latencyTiming requirements due to tight software

control loopsHuman interface requirements

R3 Dependability RequirementsR3 Dependability Requirements

ReliabilitySafetyMaintainabilityAvailabilitySecurity

Major componentsMajor components

Data Acquisition and processingCommunicationSystem logic and control algorithmInterfaceAuxiliary units

– Display– Storage– Monitoring and protection– test and diagnosis

Design and DevelopmentDesign and Development

Cost

Processing power

Memory size and Cost

Number of units

Expected life time

Throughput

Response Time

Testability/Debugging

Program Installation

Languages usedLanguages used

C

C++ Java

Linux

Ada Assembly

Embedded development toolsEmbedded development tools

Host machine

Target machine

PROM Programmers

Simulators

In Circuit Emulator

In Circuit Debugger

Millimeters

Cathode Ray Oscilloscope

Logic analyzers