Learn
3.1.5 | EMBEDDED SYSTEMS
01 | A COMPUTER INSIDE A DEVICE
An embedded system is a computer system incorporated into a larger device to perform a dedicated function, or a defined set of related functions.
A washing machine’s controller manages washing operations. A car’s anti-lock braking controller manages a braking function. These systems are designed for the needs of the device rather than for users to run many unrelated applications.
Embedded does not simply mean small. The important ideas are its place within a larger device and its dedicated purpose.
02 | DEDICATED VERSUS GENERAL PURPOSE
| Feature | Embedded system | General-purpose computer |
|---|---|---|
| Main purpose | Specific function within a device | Many different tasks |
| Software | Designed around the device’s functions | Users can run varied applications |
| User interaction | Often specialised controls, a small display or no direct interface | Often keyboard, pointing device and a flexible interface |
| Design priorities | Fit the device: cost, power, reliability, timing or size | Support a wide range of workloads |
| Examples | Washing-machine controller; car braking controller | Laptop or desktop used for documents, coding and games |
A dedicated system may have several settings and operating modes. A washing machine can offer different wash programmes while still having the dedicated purpose of controlling washing.
Not every device with one app open becomes an embedded system. A laptop displaying a timer is still designed as a general-purpose computer.
03 | WHAT IS INSIDE?
An embedded system needs processing hardware and software. It may include memory, input/output interfaces and specialised components.
| Part | Role | Washing-machine example |
|---|---|---|
| Processor | Execute the control programme | Choose the next washing stage |
| Memory | Hold programme instructions and working data | Keep selected settings and current readings |
| Input | Provide measurements or user commands | Buttons, door sensor and water-level sensor |
| Output | Display information or control equipment | Display, motor, heater and valve |
Many embedded systems use a microcontroller, which integrates a processor, memory and input/output features on one chip. Other designs use microprocessors or more complex hardware.
Do not confuse an embedded system with a single chip. The system includes the relevant hardware and software working together.
04 | FOLLOW A WASHING-MACHINE CONTROLLER
A user chooses a wash setting. A door sensor reports whether the door is closed, and a water-level sensor provides a measurement.
Settings and sensor readings→PROCESSING
Follow programme rules→OUTPUT
Control valve, motor and heater
The controller checks the input against its programme rules. For example, it can request the water inlet valve to open until a target level is reached, then change to the next stage.
The sensor measures; the processor makes programmed decisions; the valve or motor performs the physical action. These are different roles.
This is a conceptual example, not a complete appliance design. Real equipment also needs appropriate electrical control and safety mechanisms.
05 | EXAMPLES FROM EVERYDAY LIFE
| Device / context | Embedded function | Possible inputs and outputs |
|---|---|---|
| Domestic appliance | Control a washing cycle or oven temperature | Settings / temperature readings → motor or heater control |
| Car | Manage anti-lock braking or engine operation | Vehicle sensors → commands to relevant control equipment |
| Security system | Monitor events and trigger an alarm | Door or movement sensors → siren / notification |
| Lighting system | Switch or adjust lights according to rules | Light / occupancy sensor or timer → light control |
| Vending machine | Manage payment and product dispensing | Selection / payment information → dispensing mechanism and display |
A car can contain many embedded systems, each handling different functions. Saying “a car has a computer” is less precise than identifying its braking, engine or climate-control system.
06 | CHARACTERISTICS THAT FIT THE JOB
Specialised software: the programme is designed around the device’s task.
Resource limits: the system may have limited memory or processing capacity because extra capacity increases cost, power use or size.
Reliability: a device may need to operate repeatedly with little user attention. The required reliability depends on the application.
Timing: some systems must respond within a defined time. A braking controller has different timing requirements from a vending-machine display.
Power and size: a battery-powered or compact device may need energy-efficient, small components.
These are common design priorities, not a definition requiring every embedded system to be tiny, inexpensive or real-time.
07 | CONNECTED DOES NOT MEAN GENERAL PURPOSE
An embedded controller can be connected to a network. A lighting controller may receive a command through an app while still serving its dedicated lighting function.
Some embedded systems can receive software updates or new settings. Being updateable does not mean they are designed to run arbitrary desktop applications.
Conversely, internet access is not required. A standalone appliance controller can be embedded without Wi-Fi, a browser or cloud services.
08 | IDENTIFY AND JUSTIFY
Ask two questions: Is the computing system part of a larger device? And is its software focused on the device’s dedicated function?
A thermostat controller: embedded, because it is built into the temperature-control device and processes readings to control heating.
A student laptop: general purpose, because it is designed for many different applications.
A controller board built into a robot hand: it can form part of an embedded system when programmed and integrated to control the hand’s movements. The same board on a desk is not automatically an embedded system merely because it is small.
For borderline examples, state the implementation and purpose rather than guessing from appearance.
09 | COMMON MISTAKES
- Embedded means any small computer: focus on integration and dedicated purpose.
- No display is allowed: embedded devices can have displays and controls.
- Internet is required: many operate independently.
- Software can never change: some accept updates and settings.
- Dedicated means exactly one instruction: a specific function can involve complex software and many modes.
- The processor is the sensor or actuator: distinguish measurement, processing and physical output.