Describe embedded systems and provide examples

Computer Architecture – Embedded Systems (IGCSE 0478 Section 6.1)

1. What is an Embedded System?

An embedded system is a specialised computer that is built into a larger device to perform a dedicated function. It follows the basic Von Neumann architecture (CPU, memory, I/O) but is optimised for:

• One (or a small set of) specific tasks
• Strict limits on size, power, cost and real‑time performance
• Continuous, reliable operation in often harsh environments

2. Key Characteristics

• Dedicated functionality – designed for a single job (e.g., controlling a washing‑machine cycle).
• Real‑time operation – must respond to inputs within a defined deadline (e.g., an air‑bag controller fires within < 5 ms).
• Resource constraints – limited CPU speed, RAM, ROM/Flash, storage and power.
• Integrated hardware – microcontroller or microprocessor together with memory, I/O, sensors and actuators.
• Reliability & durability – expected to run continuously for years.

3. Core Computer‑Architecture Reminders (AO1)

4. Common Hardware Components

5. Software / Firmware

• Firmware – the program stored in ROM/Flash; usually written in C, C++ or (for some boards) MicroPython.
• Real‑time operating system (RTOS) – provides deterministic task scheduling, interrupt handling and timing (e.g., FreeRTOS, Zephyr).
• Bare‑metal programming – firmware runs directly on the hardware with no OS; common in very small or low‑cost devices.
• Integrated Development Environment (IDE) – tools such as Arduino IDE, MPLAB X, Keil µVision help write, compile and debug embedded code.

6. Embedded Systems in Automated Systems (Sensor → Processor → Actuator)

In an automated system the three elements work together:

1. Sensor gathers data from the environment (e.g., temperature sensor).
2. Processor (microcontroller) evaluates the data using firmware or an RTOS.
3. Actuator carries out the required action (e.g., turning a heating element on/off).

Example: a smart thermostat reads temperature, compares it with the set point, and drives a relay to switch heating or cooling.

7. Robotics (IGCSE 6.2)

Robotics combines embedded control with mechanical movement.

• Controller – usually a microcontroller or single‑board computer (e.g., Raspberry Pi, Arduino).
• Actuators – DC/stepper motors, servos, pneumatic cylinders that produce motion.
• Sensors – distance (ultrasonic), position (encoders), vision (camera) to give feedback.
• Typical examples – assembly‑line robot arm, autonomous drone, line‑following robot.

8. Artificial Intelligence (IGCSE 6.3)

AI adds “intelligence” to embedded devices.

• Expert systems – rule‑based logic stored in firmware (e.g., “if temperature > 30 °C then turn fan on”).
• Machine‑learning models – small neural‑network inference engines can run on powerful MCUs (e.g., TensorFlow Lite for microcontrollers).
• Simple AI example – a voice‑activated assistant that recognises a few commands using a pre‑trained keyword‑spotting model.

9. Internet, Digital Currency & Cyber‑Security (IGCSE 5.1–5.3)

10. Software Stack & Programming (IGCSE 4.1–4.2)

• Application software – end‑user programmes (e.g., word processor, game).
• System software – operating systems (Windows, Linux) that manage hardware resources.
• Embedded firmware – sits between hardware and any higher‑level OS; often the only software on a device.
• Programming languages – C and C++ dominate embedded work; Python is used on higher‑level boards (e.g., MicroPython on ESP32).
• Pseudocode & flowcharts – IGCSE expects students to express algorithms clearly; the same conventions apply to embedded programs.

11. Data Representation & Transmission (IGCSE 1–3)

• Binary, hexadecimal and decimal conversions – essential for setting register values and interpreting sensor data.
• Data compression (e.g., JPEG for camera images) and error‑checking codes (parity, CRC) are often built into communication protocols.
• Packet structure – start‑bit, address, payload, checksum – used in UART, SPI, CAN and Ethernet frames.

12. Algorithms, Programming Constructs & Databases (IGCSE 7–10)

• Common algorithms in embedded systems – polling loops, debounce routines, PID control, state‑machine handling.
• Control structures – if…else, while, for, switch, and interrupt service routines.
• Simple databases – key‑value storage in EEPROM or SD card (e.g., storing user settings).
• Boolean logic – used for sensor fusion and decision making (e.g., (temp>30) && (fanOff)).

13. Real‑World Examples of Embedded Systems

1. Home appliances – washing‑machine controller, microwave oven keypad, smart refrigerator temperature manager.
2. Automotive – engine control unit (ECU), anti‑lock braking system (ABS), infotainment touch screen.
3. Consumer electronics – digital camera image processor, MP3 player DAC, smartwatch health monitor.
4. Industrial control – programmable logic controller (PLC) on an assembly line, CNC machine controller.
5. Medical devices – insulin pump, portable ECG monitor, automated blood‑pressure cuff.
6. Communication equipment – Wi‑Fi router, 4G modem, satellite receiver front‑end.
7. Robotics project – Arduino‑controlled line‑following robot using IR sensors, motor driver and simple PID algorithm.
8. AI‑enabled edge device – smart camera that runs a tiny neural network to detect motion and send alerts.

14. Embedded vs. General‑Purpose Computers

15. Advantages & Limitations (Pros vs. Cons)

16. Summary – Key Take‑aways

• Embedded systems are specialised computers built into larger devices; they follow the Von Neumann model but are optimised for a single purpose.
• Core characteristics: dedicated function, real‑time constraints, limited resources, integrated hardware, high reliability.
• Typical hardware: microcontroller/microprocessor, ROM/Flash, RAM, I/O interfaces, power supply, and external sensors/actuators.
• Software is usually firmware stored in non‑volatile memory; many use an RTOS, while the simplest run bare‑metal.
• They form the hardware backbone of automated systems, robotics, and AI‑enabled edge devices.
• Examples span home appliances, automotive ECUs, industrial PLCs, medical monitors, communication gear, and classroom projects.
• Advantages: low cost, small size, low power, fast deterministic response. Limitations: inflexibility, development complexity, upgrade difficulty.
• Understanding embedded systems helps link all other IGCSE topics – data representation, networking, security, algorithms, and programming.