Electronic Systems

This section explores electronic systems Electronic systems are a core element in modern design and technology. They consist of a combination of components that work together to process inputs, perform tasks, and produce outputs. These systems are commonly used in everyday products such as alarms, lighting systems, and even home automation systems. In this revision, we will cover electronic systems, inputs, sensors, microcontrollers, control devices, and outputs.

Electronic Systems

An electronic system is a collection of electronic components that work together to complete a specific function. The system follows the basic principle of input-process-output:

• Input: The system receives information or data from sensors or switches.
• Process: A microcontroller or processor interprets the input and processes it.
• Output: Based on the processed information, the system produces an output, such as turning on a light, sounding an alarm, or controlling a motor.

Electronic systems are widely used in various applications, including home appliances, automated systems, and robotics.

Inputs

Inputs in electronic systems are the signals or data that are received by the system. These can be provided by sensors, switches, or other devices. The input is typically used to trigger an action or send information to the microcontroller for processing.

• Sensors are devices that detect physical quantities such as light, temperature, pressure, or motion, and convert them into electrical signals that can be processed by the microcontroller.

Sensors

A sensor is a device that detects a physical property and converts it into an electrical signal. Sensors are used in many applications, such as monitoring temperature, detecting motion, or measuring light levels.

Types of Sensors:

• Temperature Sensors: Measure the temperature of an environment or object.
• Example: Thermistors or thermocouples, commonly used in thermostats and weather stations.
  
   
• Light Sensors: Detect light intensity. These are commonly used in automatic lighting systems.
• Example: LDRs (Light Dependent Resistors), where resistance decreases as light intensity increases.
  
   
• Motion Sensors: Detect movement or presence. Commonly used in security systems or automated lighting.
• Example: PIR (Passive Infrared) Sensors, which detect changes in infrared radiation when a person or object moves.
  
   
• Proximity Sensors: Detect the presence or absence of an object within a certain range.
• Example: Used in touchless switches or automated doors.
  
   
• Pressure Sensors: Detect pressure changes, often used in weather stations, car tires, or gas appliances.
• Example: Piezoelectric sensors.
  
   
• Sound Sensors: Detect sound waves and convert them into electrical signals.
• Example: Microphones used in sound-sensitive devices.

Microcontrollers as Process Devices

A microcontroller is a small, programmable device that acts as the "brain" of an electronic system. It processes the inputs received from sensors and controls the outputs based on its programmed instructions. Microcontrollers are used in a wide range of electronic products, from washing machines to robotics and IoT (Internet of Things) devices.

• Microcontrollers contain a central processing unit (CPU), memory, and input/output (I/O) pins that allow them to receive data from sensors and send data to output devices.

Purpose of Process Devices (Microcontrollers)

The primary purpose of a process device, such as a microcontroller, is to:

• Interpret inputs: Process the signals received from input devices (like sensors or switches).
• Make decisions: Based on programmed conditions (e.g., if a sensor reads a certain value, perform an action).
• Control outputs: Trigger output devices (like lights or motors) to perform specific actions, such as turning on a light when a motion sensor detects movement.

Microcontrollers are programmable, meaning the user can write a custom program to dictate how the device responds to different inputs. This makes them highly versatile in different applications.

Advantages and Disadvantages of Using Microcontrollers

Advantages:

• Cost-effective: Microcontrollers are relatively cheap, especially for small or simple tasks.
• Compact size: They are small and can be embedded in products where space is limited.
• Flexibility: Programmable microcontrollers can be used in a wide variety of systems and applications.
• Efficiency: Microcontrollers can manage multiple inputs and outputs, providing fast processing and control in real-time.
• Low power consumption: Many microcontrollers are designed to be power-efficient, making them ideal for battery-operated devices.

Disadvantages:

• Complexity in programming: Programming microcontrollers can be challenging for beginners and requires understanding of languages like C or Arduino programming.
• Limited processing power: Compared to full-scale computers, microcontrollers have limited processing power, which may restrict their use in more complex systems.
• Vulnerability to damage: Sensitive to voltage fluctuations, static electricity, and environmental conditions, microcontrollers need to be protected from damage.

Programming Microcontrollers

Programming a microcontroller involves writing code that specifies how the microcontroller should respond to different inputs and control the outputs. This is typically done in a programming language like C or Arduino, and is then uploaded to the microcontroller using a computer and an appropriate development environment (e.g., the Arduino IDE).

    Steps in Programming:

• Define Inputs: Specify which sensors or switches will provide data to the microcontroller.
• Set Conditions: Program the conditions under which the system will respond (e.g., if the temperature exceeds a threshold, turn on the fan).
• Set Outputs: Program the microcontroller to activate output devices (like turning on an LED or a motor).
• Upload the Code: Once the program is written, it is uploaded to the microcontroller via a USB cable or another interface.

Control Devices

Control devices are used to manipulate or regulate the flow of electrical current or signals in an electronic system. These devices allow the microcontroller to control or switch outputs, enabling various functions in the system.

Switches: A switch is a simple device used to make or break a connection in an electrical circuit. Switches can be mechanical (e.g., a light switch) or electronic (e.g., a touch-sensitive switch). Common types include:

• SPST (Single Pole Single Throw): A basic on/off switch.
• SPDT (Single Pole Double Throw): A switch that can connect to one of two outputs.
• Push-button switches: Used in momentary on/off circuits.

Transistors: A transistor is a semiconductor device used to amplify or switch electronic signals. It is often used as a switch or signal amplifier in circuits.

• NPN Transistor: Commonly used to switch electronic devices on and off by controlling the flow of current through the transistor.
• MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor): Used for controlling large currents or voltages in more complex systems.

Resistors: A resistor is a component that resists the flow of electric current. It is used to limit or control the current flowing through a circuit and to protect other components from damage.

• Variable Resistors (Potentiometers) are used to change the resistance in a circuit, commonly used in volume controls or brightness settings.

Outputs

Outputs are the actions or results that the system produces after processing inputs. Outputs in electronic systems are typically in the form of light, sound, or movement, which are activated by the microcontroller based on the programmed conditions.

    Light Outputs:

• LEDs (Light Emitting Diodes): Commonly used for indicating states (on/off), displaying information, or providing visual feedback in electronic systems.
• LCD Screens: Used to display text or images in more complex systems, such as digital clocks or temperature displays.

    Sound Outputs:

• Buzzer: A simple sound-producing device used in alarms or notification systems. It produces a buzzing sound when activated.
• Speakers: Used in more complex systems to produce a variety of sounds, including music, speech, or alarms. They convert electrical signals into audible sound.

Example of an Output System:

• Input: A motion sensor detects movement.
• Process: The microcontroller processes the signal and checks if the movement exceeds a certain threshold.
• Output: The microcontroller turns on an LED or activates a buzzer to alert the user.

In GCSE Design and Technology, understanding the role of electronic systems, microcontrollers, and the components that make them work is crucial for designing products with embedded control systems. Inputs, sensors, microcontrollers, and control devices work together to process data and produce useful outputs, such as light, sound, or movement. By programming microcontrollers effectively, designers can create interactive, automated, and responsive systems that improve functionality and user experience.