Systems
- A system takes an input, processes it, and produces an output. Designers use block diagrams to show this.
- Example: a night light. Input: a light sensor detects darkness. Process: a microcontroller decides to switch on. Output: an LED lights up.
Inputs
- Light sensors (such as light-dependent resistors) detect light levels.
- Temperature sensors (such as thermistors) detect heat.
- Pressure sensors detect force, such as in a pressure mat.
- Switches (push, toggle, reed, tilt and micro switches) are simple inputs that turn a circuit on or off.
Processes and outputs
- Programmable components, such as microcontrollers (PICs), can be programmed to make decisions, count, time and control outputs. They reduce the number of components needed and can be reprogrammed.
- Outputs include buzzers and speakers (sound), lamps and LEDs (light), and motors (movement).
- LEDs are efficient, long lasting and come in many colours. Buzzers are cheap and simple for alarms.
Why designers use systems
- Breaking a product into input, process and output makes complex products easier to design and to fix.
- Programmable components make products smarter, such as a thermostat that switches heating on at set times.
Key terms
- System
- A set of parts that takes an input, processes it, and gives an output.
- Input
- The part of a system that detects a change, such as a sensor.
- Process
- The part of a system that decides what to do.
- Output
- The part of a system that does something, such as a buzzer.
- Microcontroller
- A programmable chip that controls a system.
- Light-dependent resistor
- A sensor whose resistance changes with light level.
- Thermistor
- A sensor whose resistance changes with temperature.
- LED
- A light-emitting diode: an efficient light output.