Characteristics of Embedded Systems

An embedded system is built with just enough of everything to do its own dedicated job well. The characteristics below are typical rather than strict rules: they explain why an embedded system is a good fit for the device it is built into.

Characteristic	What it means	Why it suits the device
Limited processing power and memory	A modest processor and small memory, matched to the one task.	It needs only enough speed and storage for its job, so extra capacity would add cost and power use.
Small size	A small processor and little memory take up little space.	It fits inside the larger device, even a compact or handheld one.
Low power use	It draws little electricity and runs cool.	It can often run from batteries and costs little to run.
Low cost	Simpler, smaller parts are cheap to make in large numbers.	The manufacturer keeps the price of the whole product down.
High reliability	Fewer parts, and simple software tested for one task, so less can go wrong.	It is less likely to fail over years of use, which matters if it controls something important.
Continuous running	Designed to keep working for long periods without attention.	You never need to restart it or supervise it.
Simple or absent interface	Often only minimal controls, or none at all.	You only start it or make a simple choice, so extra controls would add cost and complexity.

Matching characteristics to the device

Imagine a bike computer that shows your speed and distance. It only has to count wheel turns and do simple sums, so a small processor and little memory are enough, and it is small enough to clip to the handlebars. It runs from a coin battery because it uses little power, it is cheap enough to add to a bike, and it keeps working for hours on a ride without attention. A couple of buttons are all you need to switch between speed and distance, so the interface stays simple. Each characteristic matches a need of the device, which is why the embedded system suits it.

Matching characteristics to the device

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