Embedded Systems
Definition
An embedded system is a computer with a dedicated function built into a larger device. It does one specific job, not multiple like a general-purpose computer.
Key Fact
The vast majority of all computer processors manufactured are for embedded systems, not for laptops or desktops.
Examples
| Scale | Examples |
|---|---|
| Small/portable | Digital watches, calculators, hearing aids |
| Domestic | Coffee machines, washing machines, microwaves, smart TVs |
| Automotive | Car engine management systems, ABS braking, airbag controllers |
| Industrial | Traffic lights, factory controllers, CNC machines |
| Medical | Insulin pumps, pacemakers, hospital monitoring equipment |
| Aerospace | Apollo guidance computer, aircraft flight control systems |
Key Properties
| Property | Detail |
|---|---|
| Dedicated function | Performs one specific task; not general-purpose |
| Low power consumption | Often battery-powered or designed for energy efficiency |
| Small physical size | Must fit inside the host device |
| Low cost per unit | Mass production allows economies of scale |
| High reliability | Optimised for the single task, reducing failure points |
| Rugged operating range | Must handle temperature, vibration, etc. |
| Limited processing resources | Less powerful CPU/memory than a general computer |
Trade-offs
Advantages (from single-purpose design)
- Can be highly optimised for its specific task
- Smaller, lighter and cheaper to produce
- More reliable, fewer software components that could fail
- Low power draw
Disadvantages
- Limited resources make them more difficult to program
- Harder to interact with (no standard OS, no keyboard/screen)
- Cannot be easily repurposed for a different task
- Upgrading or patching can be difficult
Hardware
Modern embedded systems are typically built around a microcontroller, a single chip integrating:
- CPU
- RAM
- ROM (to store the dedicated program)
- I/O interfaces
This integration reduces size and cost compared to using separate components.
Economies of Scale
Because embedded systems are mass-produced (e.g., millions of coffee machines), the cost per unit drops significantly. The fixed cost of development is spread across a huge production run.
Exam Questions
Q: What is the primary definition of an embedded system?
A computer system designed for a specific, dedicated function within a larger mechanical or electrical device.
Q: State two typical properties of an embedded system.
Any two of: low power consumption, small physical size, low cost, high reliability, limited processing resources, rugged operating range.
Q: Why can an embedded system be highly optimised?
Because it only needs to perform one specific task, so resources and software can be tailored exactly for that purpose.
Q: What is the main disadvantage of an embedded system’s limited resources?
Limited processing resources can make the system significantly more difficult to program and interact with.
Exam Tip
Always state dedicated function in answers. Contrast with a “general-purpose computer” that can run any software.