Embedded Systems

This lesson covers embedded systems — dedicated computer systems built into larger devices to perform specific functions. For the OCR H446 exam, you must understand the characteristics of embedded systems, provide examples, compare them with general-purpose computers, and discuss the Internet of Things (IoT).

What Is an Embedded System?

An embedded system is a computer system that is integrated into a larger device and designed to perform a specific, dedicated function. Unlike a general-purpose computer (which can run any software), an embedded system typically runs a fixed program stored in ROM or flash memory.

Key Characteristics

Characteristic	Explanation
Dedicated function	Designed to do one specific task or a small set of related tasks
Embedded within a larger system	Not a standalone computer — it is built into a product
Real-time operation	Often must respond to inputs within strict time limits (milliseconds or microseconds)
Limited resources	Typically has a small processor, limited RAM and limited storage compared to a PC
Low power consumption	Often battery-powered or must run continuously with minimal energy use
Runs firmware	Program is stored in ROM or flash memory; rarely updated by the user
Minimal or no user interface	May have no screen or keyboard; interaction might be through buttons, LEDs, or sensors
Low cost per unit	Designed for mass production; cost must be minimised
High reliability	Must work consistently without crashes — often in safety-critical applications

Examples of Embedded Systems

Device	Embedded Function	Typical Processor
Washing machine	Controls water temperature, spin speed, cycle timing	Microcontroller (e.g. PIC, ARM Cortex-M)
Microwave oven	Controls magnetron power, timer, turntable motor	Simple microcontroller
Car engine management	Monitors sensors (temperature, oxygen, speed), controls fuel injection, ignition timing	Automotive microcontroller
Digital watch	Keeps time, displays date, alarm function	Ultra-low-power microcontroller
Traffic light controller	Manages light sequences, responds to sensors and pedestrian buttons	PLC or microcontroller
Smart thermostat	Monitors temperature, controls heating/cooling, learns user preferences	ARM-based SoC with Wi-Fi
Anti-lock braking system (ABS)	Detects wheel lock-up and rapidly adjusts brake pressure	Real-time microcontroller
Fitness tracker	Monitors heart rate, steps, sleep; displays data	ARM Cortex-M with Bluetooth
Router	Manages network traffic, assigns IP addresses, provides firewall	MIPS or ARM SoC running embedded Linux
TV remote control	Sends infrared signals corresponding to button presses	Simple 8-bit microcontroller