Eduqas A-Level Electronics Microcontrollers and programmable systems: architecture, assembly, interfacing and the NEA

What this module actually demands

Microcontrollers and programmable systems is where the whole course comes together into working, programmable products. It spans Component 2 (microcontrollers and interfacing) and the Component 3 non-exam assessment (design and realisation). The examiners reward a clear grasp of the microcontroller's architecture and interfacing, the ability to program it in assembly language, safe and correct driving of real loads, and the disciplined systems approach to designing, testing and evaluating a complete build.

This guide walks through the topics in order and sets out the exam patterns Eduqas repeats. Each topic has a matching dot-point page with practice; this overview ties them together.

The microcontroller and its program

Microcontroller architecture and interfacing describe the CPU, memory and I/O ports, digital pins, the pull-up and pull-down resistors that give switches a defined level, and the ADC, PWM and timer peripherals that connect to the analogue and power worlds. Assembly language programming covers instructions and registers, reading inputs and writing outputs, branching and loops, delay loops, and the flowchart-code-assemble-test development cycle required for the non-exam assessment.

Interfacing and the complete system

Sensing interfaces and actuator control condition and read sensor inputs (with debouncing and the ADC), drive outputs through transistor, MOSFET and relay drivers, control a motor's speed and direction with PWM and an H-bridge, and close the loop with feedback control. Programmable system design and testing apply the systems approach (input, process, output, power), block diagrams, systematic testing and fault-finding, evaluation against a specification, and health and safety, the method behind Component 3.

How this module is examined

A typical Eduqas profile for this content:

• Explanation. Microcontroller architecture and peripherals, why pull resistors and flyback diodes are needed, switch bounce and debouncing, and open-loop versus closed-loop control.
• Programming. Describing an assembly program as a flowchart or pseudocode, the read-test-branch-write loop, delay loops, and the development cycle.
• Design. Driving loads safely, the H-bridge and PWM for motors, and structuring a product as input, process, output and power subsystems.
• Realisation (Component 3). Designing, building, testing systematically and evaluating a complete system against a specification, with documentation and safety.

Check your knowledge

A mix of recall and explanation questions covering the module. Attempt them under timed conditions, then check against the solutions.

1. Name the three main internal parts of a microcontroller. (3 marks)
2. State what happens to a microcontroller input pin left floating. (1 mark)
3. State the type of instruction used to make a decision in an assembly program. (1 mark)
4. State what an H-bridge allows you to do with a DC motor. (1 mark)
5. State the difference between open-loop and closed-loop control. (2 marks)
6. Name the four subsystems of the systems approach. (2 marks)