UK How an embedded system works
An embedded system is a computer system built into a larger device to perform one dedicated function. It combines a processor, memory, input and output, and software, and it usually works out of sight: the user sees a thermostat, a ticket machine or a car, not the computer inside it.
Most embedded systems follow the same loop. Sensors or inputs report what is happening, such as a temperature, a button press or a wheel speed. The processor runs fixed software that decides what to do, and outputs act on the result by switching a heater, driving a motor or updating a display. Because the job is known in advance, the hardware and software are sized for it, which keeps the system small, low in power and predictable.
The software is often called firmware, because it is stored in non-volatile memory and rarely changes during the device’s life.
The parts of an embedded system
Even very different embedded systems share the same building blocks:
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Processor. A microcontroller (MCU) with memory and peripherals on one chip for simple control tasks, a system on chip (SoC) with application cores, graphics and often an AI accelerator for richer devices, or an FPGA where custom logic is needed.
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Memory. Flash for the program and data, and RAM for working memory, from a few kilobytes on a small MCU to several gigabytes on an SoC.
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Input and output. General-purpose I/O, analogue-to-digital converters, UART, I2C, SPI, CAN and Ethernet connect the processor to sensors, actuators and other systems.
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Power and timing. Regulators, a clock source and often a watchdog timer that restarts the system if the software stops responding.
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Software. Bare-metal code for the simplest devices, a real-time operating system (RTOS) such as FreeRTOS or Zephyr where tasks must meet deadlines, or embedded Linux, Android or Windows IoT on larger systems.
Microcontroller, SoC or embedded computer
Embedded systems range from a single microcontroller to a fanless computer running AI models. The table shows the main classes and where each one fits.
| Class | Typical processor | Memory | Software | Typical use |
|---|---|---|---|---|
| Microcontroller-based | Arm Cortex-M, RISC-V, 8-bit MCUs | KB to a few MB | Bare metal or RTOS | Appliances, sensors, motor control |
| SoC-based board | Arm Cortex-A, such as NXP i.MX or Rockchip | 1–16 GB | Embedded Linux or Android | HMIs, gateways, smart displays |
| Embedded x86 computer | Intel Atom, Core or AMD Ryzen Embedded | 4–64 GB | Windows IoT or Linux | Machine control, vision, kiosks |
| Edge AI computer | NVIDIA Jetson or x86 with a GPU or NPU | 8–64 GB | Linux with AI frameworks | Inspection, robotics, video analytics |
The bigger the class, the more the system looks like a conventional computer. A system on chip combines CPU, GPU and I/O in one package, which is what allows a credit-card-sized board to run a full operating system.
Types of embedded system
Embedded systems are often grouped by how they behave. One device can belong to several groups.
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Real-time systems. Must respond within a fixed time. In a hard real-time system, such as an airbag controller, a late answer is a failure; in a soft real-time system, such as a media player, an occasional delay is tolerated.
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Standalone systems. Work on their own without a host computer, such as a microwave oven or a digital camera.
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Networked systems. Connect over Ethernet, Wi-Fi, cellular or fieldbus to share data, such as a building controller or an IoT sensor.
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Mobile systems. Run from batteries in portable devices, such as handheld scanners, wearables and medical monitors.
Examples of embedded systems
Embedded systems far outnumber PCs. A modern car contains dozens of electronic control modules for the engine, brakes, airbags and infotainment. At home they run washing machines, routers, smart meters and TVs. In industry, a programmable logic controller is an embedded system for machine control, and so are robot controllers, drives, HMIs and condition monitoring sensors. Hospitals rely on them in infusion pumps, patient monitors and imaging equipment, and transport uses them in ticketing, signalling and on-board train systems.
The line between an embedded system and an ordinary computer is the job, not the hardware. A PC that runs one fixed application inside a machine, sealed in a cabinet and never used for anything else, is acting as an embedded system. That is the role of an embedded computer: a complete, often fanless computer built into equipment. Our guide to choosing and deploying embedded computers covers that hardware in depth.
Quick answers on embedded systems
Embedded systems: common questions
What is an embedded system, with an example?
A dedicated computer inside a device. A washing machine’s controller is a typical example: a microcontroller reads the door switch, water level and temperature sensors, and runs the wash programme by driving the motor, valves and heater.
Why is a microcontroller used in an embedded system?
Because it puts everything on one chip. A microcontroller combines the processor, flash, RAM and peripherals such as timers and ADCs, so the system needs few other parts, uses little power and costs little.
What is an RTOS in an embedded system?
A real-time operating system. It schedules tasks so that time-critical work always meets its deadline, and it is small enough to run on a microcontroller.
Is Arduino an embedded system?
It is a board for building one. It is a microcontroller development board; once it is programmed for a single job and built into a project, that project is an embedded system.
Is a smartphone an embedded system?
Not as a whole. A smartphone is a general-purpose computer that runs any app, but it contains embedded systems, such as the modem, power management and camera controllers.
We supply the hardware for embedded systems at board and system level, from Arm SBCs to embedded box PCs, and integrate the memory, storage, I/O and operating system image each design needs as standard.