Characteristics of an embedded System

An embedded system is a computer system consisting of hardware and software components, which are embedded into a device to perform a specific function. An embedded system has its own unique characteristics, which make us identify and decide the system as the embedded system.

Washing machines, ATM machines, microwave ovens are some of the examples of embedded systems, as they are used for a specific task. Since Embedded systems are used in real-time applications, they are also called real-time embedded systems. These systems have a special operating system called a real-time operating system inside the device.

There are different classifications of embedded systems. The classifications are based on their complexity and functional requirements.

Based on the complexity of the embedded systems, they are classified into small-scale embedded systems, medium-scale embedded systems and large-scale embedded systems or sophisticated embedded systems.

Based on functional requirements, the embedded systems are classified into standalone embedded systems, mobile embedded systems, real-time embedded systems and networked embedded systems.

The embedded system in each classification has its own characteristics. Below are some of the characteristics of embedded systems.

In the following section, let us discuss all the characteristics of an embedded system.

Performs specific Function

All embedded systems are designed to execute a specific function repeatedly. For example, if you consider a washing machine, its function is only to wash clothes. Washing is its dedicated functionality and it cannot be used for any other purposes like cooling or heating.

Similarly, an ATM machine is used to withdraw money and do transactions but it cannot be used for controlling room temperature. Similarly, pagers, microwave oven, automotive cruise control systems, modems are some of the applications which perform specific functions.

Tightly Constraint system

Whatever system is being designed, they have certain constraints. In the same way, an embedded system has several constraints like product cost, performance, size and power. In fact, these four parameters decide the success of any embedded System.

Consider an example of buying a mobile phone. If the mobile phone costs in lakhs, would you buy it? No, instead you look for different options for low-budget phones.

If it takes half an hour for making a call and if it also hangs frequently, would you opt it? No Way, the frustration level will rise if the phone hangs continuously.

What would you do, if the phone is weighing 3 kilograms, will you prefer it? No, you always prefer less-weight products. The mobile phone should also be capable of retaining the charge for some reasonable amount of time. Else the battery will drain faster and you have to keep the charger handy all the time.

What does it mean? The cost of the product, its performance, size and power always matter the most while designing an embedded system.

Real Time and Reactive behavior

A real-time system is a system intended to serve real-time applications which process the data as it comes in, typically without any buffering delays. If there occurs any delay in responding, then the result might be dangerous.

Let us take an example of a person traveling in a car. Unfortunately, a lorry seems to be coming opposite to the car. What would the driver do?

The driver would apply the brake. Immediately after applying the brake, the car should stop without delay. This is a real-time and reactive behavior of the system. The brake may be applied at any point in time. So, when an embedded system is operating in real-time, it must be in a situation to respond to its input without any delay in execution.

An automotive cruise control system, flight landing gear control, ECG machine output, GPS tracking device are some of the examples of real-time embedded systems.

Perform Complex function

The processor inside the embedded system should perform operations that are complex in nature. Let us consider an example of a washing machine. It is used to wash clothes at different temperatures and at different timings. It is also used to dry the clothes, drain the water in tub, clean the tub, etc.

To perform these functions, it needs a lot of complex algorithms. Many embedded systems are distributed into smaller units to perform complex functions.

Minimal user Interface

Generally, embedded systems have a simple user interface, an interesting characteristics of embedded systems. In older days, mobile phones with keypads are available in the market. But look at the phone available in our hands now. Todays’ phone has become smarter with the least interfaces.

So designing a system with an easier and comfortable interface is most important. At the same time, it should have options required for the operation of the device.

A fully automatic washing machine works on its own, which has a minimal user interface. In other examples like ATM machines, microwave ovens, etc you can look at the compact interface provided for the user for its operation.

Operates in Harsh environment

The embedded system is designed to operate in different environments where humans cannot enter, whether it is a cold or hot condition. Whatever may be the condition, the systems designed to work in that condition should withstand that environment.

The designers should always remember the operating environment while designing an embedded system. For example, if a system is designed to operate in a rainy condition, then there should not be any compromise for the formation of corrosion in the system.

Some environments may have vibrations, shock, power fluctuations, etc. These factors are to be considered while designing an embedded system for that condition.

Requires less power

For most embedded systems, power management is one of the critical factors in its design. The design should be in such a way that the heat dissipation should be minimized. If not, we have to install cooling equipment to reduce the heat produced. But that will lead to a bulky product.

Also, embedded systems like digital cameras, digital watches, space rovers operate independently. These systems are operated with a battery mounted inside the system. Hence choosing the low-power components with power-saving modes is important while designing a system.

Let us summarize the characteristics of embedded systems as follows.

• All the embedded systems are task-specific. They perform the same task continuously during their entire lifetime. A washing machine will always function only as a washing machine.
• Embedded systems are built to achieve certain efficiency levels with a tightly constraint system. They are small-sized, can work with less power and are not too expensive.
• Embedded systems are created to perform the task within a certain time frame. Hence called real time embedded systems. It must therefore perform fast enough. A car’s brake system, if exceeds the time limit, may cause accidents.
• Embedded systems like fully automatic washing machine works on its own with its minimal user interface.
• Some embedded systems are designed to react to external inputs and react accordingly. A thermometer, a GPS tracking device, weather monitoring system are the examples of reactive embedded system.
• They are expected to operate for longer durations without the user experiencing any difficulties.
• Embedded systems require some peripherals to connect the input and output devices.
• They are designed to operate with less power.

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