What is an Embedded System?

An embedded system is a combination of hardware and software that is designed to carry out a certain task or tasks, meaning it has a specific function. They are ‘embedded’ within a larger electrical system. General purpose computers such as personal computers (PC’s) on the other hand, are designed to satisfy a wide range of needs.

Embedded systems can be found in a variety of common electrical appliances today, such as in mobile phones, industrial machines, automobiles, cameras, household appliances, airplanes, vending machines and toys as well as in medical equipment such as ECG recorders.

Embedded systems are usually based on micro controllers (however in the past they were mostly based on microprocessors). The basic difference between a microprocessor and a micro controller is simply that microprocessors contain only the CPU – they don’t have an inbuilt RAM or ROM, so these needed to be added externally. Micro controllers however are superior in the sense that they have a CPU as well as a fixed amount of RAM and ROM.
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Embedded systems need to be very reliable as issues with the embedded system can have devastating consequences in terms of the larger system it is part of.
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A simple depiction of the architecture of an embedded system: 

Hardware components of an embedded system:

• CPU
• ROM and RAM
• Input devices
• Output devices
• Communication interfaces
• Circuitry

Types 

Embedded systems can be classified in the following four categories based on performance and functional requirements:

• Stand-alone embedded systems – these are obviously ‘stand-alone’ systems. They don’t require a host system. Examples of these can be found in video game consoles and microwave ovens.
• Real time embedded systems – these are used when a specific task needs to be done in a specific time frame. They follow strict deadlines. These are further classified into soft and hard real time systems. Soft real time systems have deadlines, however if these are not met, there is no significant harm (e.g. a time delay between pressing a button on your TV remote and the TV sensing it and changing the channel). Hard real time systems are found in industrial machines for example, where strict deadlines need to be adhered to.
• Networked embedded systems – these are connected to a network to access resources
• Mobile embedded systems – as the name suggests, these are found in portable electronics

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Advantages

• Since an embedded system is specialized for carrying out the same tasks, there is rarely any need to change the hardware
• Compact size
• Low cost
• Simple design

Various Embedded Devices

Links

1. WIKIPEDIA 
2. YOUTUBE
3. IoT AGENDA
4. TECHWALA
5. SLIDESHARE
6. ENGINEERS GARAGE
7. EFXKITS

Questions

• Why was it considered such a significant improvement when micro controllers were used rather than microprocessors?
• Before we had embedded systems, how did all the systems that use them work/run?
• What is the average life-span of an embedded system considering the fact that we don’t want to have to replace them?