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Northern IrelandTechnology and Design

A2 1 Electronic and Microelectronic Control Systems

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are analogue signals converted to digital so a microcontroller can process them?

Analogue and digital signals, the binary number system, analogue-to-digital and digital-to-analogue conversion, resolution and quantisation.
A CCEA A-Level Technology and Design answer on analogue and digital signals, binary numbers, analogue-to-digital (ADC) and digital-to-analogue (DAC) conversion, and how the number of bits sets the resolution and the size of each quantisation step.
12 min answer →

What is a microcontroller (PIC), and why does it replace hard-wired logic in control systems?

The microcontroller (PIC): architecture, input/output ports, memory, the program cycle, and the advantages of programmable control over discrete logic.
A CCEA A-Level Technology and Design answer on the microcontroller (PIC), its architecture of processor, memory and input/output ports, the fetch-execute program cycle, and the advantages of programmable control over hard-wired discrete logic.
12 min answer →

How does feedback turn an open-loop system into a self-correcting closed-loop one, and what is PID control?

Open- and closed-loop control, feedback and the error signal, and proportional, integral and derivative (PID) control.
A CCEA A-Level Technology and Design answer on open- and closed-loop control systems, the role of feedback and the error signal, and the proportional, integral and derivative (PID) control modes.
12 min answer →

How are op-amps used to amplify, sum and difference signals in control systems?

The operational amplifier as a summing amplifier, difference amplifier and voltage follower, with the ideal op-amp assumptions.
A CCEA A-Level Technology and Design answer on the operational amplifier in control systems - the summing amplifier, the difference (subtractor) amplifier and the voltage follower - and the ideal op-amp assumptions used to analyse them.
12 min answer →

How is a control program designed using flowcharts, and what programming structures does it use?

Flowcharts and their symbols, programming constructs (sequence, selection, iteration), inputs/outputs, delays and subroutines for microcontroller control.
A CCEA A-Level Technology and Design answer on designing microcontroller control programs with flowcharts and their standard symbols, and the programming constructs of sequence, selection (decision) and iteration (loops), plus inputs, outputs, delays and subroutines.
12 min answer →

How do flip-flops store a bit, and how are they combined into counters?

Sequential logic: the bistable/flip-flop (set-reset, D and JK), latching, and binary counters and frequency division.
A CCEA A-Level Technology and Design answer on sequential logic, the set-reset, D and JK flip-flops as one-bit memory and latches, and how flip-flops are chained into binary counters and frequency dividers.
12 min answer →