How does a systems approach using inputs, processes and outputs control a product?
The systems approach of input, process and output, the function of sensors and output devices, and the use of programmable components such as microcontrollers in electronic products.
A focused answer to the WJEC GCSE Design and Technology core technical principle on electronic systems, covering the input-process-output systems approach, sensors and output devices, and the use of programmable components such as microcontrollers.
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What this topic is asking
WJEC's core content includes a systems approach to electronic products. You need to understand how a product is broken into input, process and output, what sensors and output devices do, and why designers use programmable components such as microcontrollers. This is core knowledge for Unit 1 across all routes, and it links closely to mechanical devices and to designing with electronics in the NEA.
The systems approach: input, process, output
Input devices (sensors)
Output devices
Programmable components
Why a systems approach helps designers
A systems approach lets a designer plan and explain how a product works at the block level, swap components in and out, and locate faults block by block. It also lets the same control chip be reused across many products, only the program changing, which is faster and cheaper than designing a new circuit each time.
Try this
Q1. Name the three blocks of a systems diagram in order. [3 marks]
- Cue. Input, then process, then output.
Q2. State a suitable input device for detecting darkness. [1 mark]
- Cue. A light-dependent resistor (LDR).
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC-style4 marksDraw and label a systems diagram for an automatic night light, naming a suitable input, process and output.Show worked answer →
A four mark question testing the systems approach. The diagram should show three labelled blocks joined by arrows left to right: INPUT containing a light-dependent resistor (LDR) to detect darkness (1 mark); PROCESS containing a microcontroller or comparator that decides when it is dark enough (1 mark); OUTPUT containing an LED or lamp that switches on (1 mark). The final mark is for arrows showing the flow input to process to output (1 mark). Markers reward correct block order, a sensible component in each block, and the signal-flow arrows. A common error is to put the output device in the input block.
WJEC-style3 marksExplain one advantage of using a programmable microcontroller instead of fixed wiring in a product.Show worked answer →
A three mark Explain question. A microcontroller can be reprogrammed to change how the product behaves without rewiring it, so the same hardware can do different jobs or be updated (1 mark). It replaces many separate components with one chip, making the circuit smaller, cheaper and more reliable (1 mark). It can take several inputs and control several outputs with decision-making in software, such as timing or counting, which fixed wiring cannot easily do (1 mark). A weaker answer just says it is modern without explaining the design benefit.
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