Embedded Systems – An Overview

By Jairam Sankar. He is currently pursuing B.Tech in ECE from RSET, Cochin

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Embedded systems are a cornerstone of the electronics industry today. Embedded systems are used in almost all the areas like consumer, cooking, industrial, automotive, medical, commercial and military applications.

What is a system?

A system is a way of working, organizing or doing one or many tasks according to a fixed plan, program or set of rules. A system is also an arrangement in which all its units assemble and work together according to the plan or program.
Examples: 1) Watch- It is a time display SYSTEM
2) Washing Machine- It is an automatic clothes washing SYSTEM

Embedded System

As its name suggests, Embedded means something that is attached to another thing. An embedded system can be thought of as a computer hardware system having software embedded in it. An embedded system can be an independent system or it can be a part of a large system. It offers many benefits such as sophisticated control, precision timing, low unit cost, low development cost, high flexibility, small size, and low weight. These basic characteristics can be used to improve the overall system or device in various ways:
• Improved performance
• More functions and features
• Reduced cost
• Increased dependability

Because of these benefits, billions of microcontrollers are sold each year to create embedded systems for a wide range of products. In other words : An embedded system is a microcontroller or microprocessor based system which is designed to perform a specific task. For example, a fire alarm is an embedded system; it will sense only smoke.

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[stextbox id=”info”]Do you want to know what is the difference between microcontroller and microprocessor?
microcontroller vs microprocessor[/stextbox]

Embedded systems contain two main elements:

Embedded system hardware: As with any electronic system, an embedded system requires a hardware platform on which to run. The hardware will be based around a microprocessor or microcontroller. The embedded system hardware will also contain other elements including memory, input output (I/O) interfaces as well as the user interface, and the display.

Embedded system software: The embedded system software is written to perform a particular function. It is typically written in a high level format and then compiled down to provide code that can be lodged within a non-volatile memory within the hardware.

Basic Structure of an Embedded System

Block diagram of an embedded system

The following illustration shows the basic structure of an embedded system:

The various blocks of an embedded system is briefly explained below:
Sensor – It measures the physical quantity and converts it to an electrical signal which can be read by an observer or by any electronic instrument like an A2D converter. A sensor stores the measured quantity to the memory.
A-D Converter – An analog-to-digital converter converts the analog signal sent by the sensor into a digital signal.
Processor & ASICs – Processors process the data to measure the output and store it to the memory.
D-A Converter – A digital-to-analog converter converts the digital data fed by the processor to analog data.
Actuator – An actuator compares the output given by the D-A Converter to the actual (expected) output stored in it and stores the approved output.

Embedded System Hardware
When using an embedded system there is a choice between the use of a microcontroller or a microprocessor.

Microcontroller based systems: A microcontroller is essentially a CPU, central processor unit, or processor with integrated memory or peripheral devices. As fewer external components are needed, embedded system using microcontrollers tend to be more widely used. The basic block diagram is given below:

Screen Shot 2016-07-04 at 4.06.30 PM

• Microprocessor based systems: Microprocessors contain a CPU but use external chips for memory and peripheral interfaces. As they require more devices on the board, but they allow more expansion and selection of exact peripherals, etc, this approach tends to be used for the larger embedded systems. The basic block diagram is given below:

block diagram of microprocessorEmbedded systems software

One of the key elements of any embedded system is the software that is used to run the microcontroller.

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