Embedded System Design and Development Introduction to Embedded System

Embedded Systems Embedded Systems Embedded - Fix firmly in a surrounding areas System - Set of connected things

Embedded 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 Essence An 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 ? 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 CONNECTED

Applications

Characteristics 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

Categories

Classification 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.

Failure 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 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 software 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 Requirements Types of requirements imposed by embedded applications: R1 Functional Requirements R2 Temporal Requirements R3 Dependability requirements

R1 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 Requirements Tasks may have deadlines Minimal latency jitter Minimal error detection latency Timing requirements due to tight software control loops Human interface requirements

R3 Dependability Requirements Reliability Safety Maintainability Availability Security

Major components Data Acquisition and processing Communication System logic and control algorithm Interface Auxiliary units – Display – Storage – Monitoring and protection – test and diagnosis

Design and Development Cost Processing power Memory size and Cost Number of units Expected life time Throughput Response Time Testability/Debugging Program Installation

Languages used C C++ Java Linux Ada Assembly

Embedded development tools Host machine Target machine PROM Programmers Simulators In Circuit Emulator In Circuit Debugger Millimeters Cathode Ray Oscilloscope Logic analyzers