How does a microcontroller control an electronic system, and how is its program planned with a flowchart?
Microcontrollers: the microcontroller as a programmable processing subsystem, inputs and outputs, and planning a control program with a flowchart.
An Eduqas GCSE Electronics answer on microcontrollers: the microcontroller as a programmable processing subsystem with input and output pins, the advantages of programming over fixed logic, and planning a control program with a flowchart using the standard symbols.
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What this dot point is asking
Eduqas wants you to describe a microcontroller as a programmable processing subsystem with input and output pins, give the advantages of programming over fixed logic, and plan a control program with a flowchart using the standard symbols. The microcontroller is the modern, flexible processing block at the heart of most systems.
The answer
The microcontroller as a processing subsystem
Inputs and outputs
Why use a microcontroller
Planning with a flowchart
Examples in context
Microcontrollers run most modern electronic systems: a washing machine, a microwave, a thermostat and a toy all use a microcontroller reading sensors and switches and driving outputs through transistor or MOSFET stages. Their reprogrammability is why one chip design can serve many products. In the course they replace large amounts of fixed logic with a single programmable block, and the flowchart is the standard way the non-exam assessment expects a control program to be planned before it is coded and tested.
Try this
Q1. State one advantage of a microcontroller over fixed logic gates. [1 mark]
- Cue. Its behaviour can be changed by reprogramming without rewiring (or one chip replaces many components).
Q2. State the flowchart symbol used for a yes/no test and its shape. [1 mark]
- Cue. A decision, drawn as a diamond.
Q3. State why a microcontroller output pin usually drives a load through a transistor. [2 marks]
- Cue. A pin can supply only a few milliamps, so a higher-current load needs a transistor (or MOSFET) switch.
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 20194 marksState two advantages of using a microcontroller rather than fixed logic gates to control an electronic system.Show worked answer →
Advantages (up to 4 marks, 2 each): (1) the behaviour is set by a program, so it can be changed by reprogramming without rewiring the circuit, making it flexible and easy to update. (2) A single chip can replace many logic gates and timers, reducing the part count, size and cost. Other acceptable points: it can perform complex decisions, timing and arithmetic; it can store data; and it can be reused for different products.
Markers reward two distinct, valid advantages such as reprogrammability (change behaviour without rewiring) and replacing many components with one chip.
Eduqas 20225 marksDraw or describe a flowchart for a system that lights an LED while a push-button is pressed and turns it off when the button is released, looping continuously. Name the flowchart symbols you use.Show worked answer →
Structure (up to 4 marks): start (terminator), then a decision (diamond) asking "is the button pressed?"; if yes, a process (rectangle) to turn the LED on; if no, a process to turn the LED off; both paths loop back to the decision, so the system checks the button repeatedly.
Symbols (1 mark): terminator (rounded box) for start/stop, process (rectangle) for an action such as "LED on", decision (diamond) for a yes/no test, and arrows for the flow direction.
Markers reward a correct loop with a decision testing the button and processes setting the LED, plus correct naming of the terminator, process and decision symbols.
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Sources & how we know this
- WJEC Eduqas GCSE (9-1) Electronics specification (C490) — WJEC Eduqas (2017)