Eduqas A-Level Electronics Microcontrollers and programmable systems overview quiz quiz

Transformer, rectifier and regulator

Resistor, capacitor and inductor

CPU, memory and input/output ports

Anode, cathode and gate

To limit the current through the switch only, protecting the contacts from the full supply current

To convert the digital input pin into an analogue input that can read a continuous range of voltages

To increase the clock speed of the processor so that it can sample the switch input far more often

To give the pin a defined logic level when the switch is open, instead of floating

Logic 1 (high)

Logic 0 (low)

An analogue value

It floats

The pulse-width-modulation (PWM) output, which sets an average voltage by varying the duty cycle

The analogue-to-digital converter (ADC)

The timer or counter peripheral, which measures elapsed time or counts external pulses in hardware

The serial communications port, which sends and receives data one bit at a time to other devices

External memory chips wired to the processor bus to extend the available program and data storage

Output transducers such as motors and lamps that convert electrical signals into physical action

Small fast storage locations inside the CPU

The positive and negative power supply rails that distribute voltage to every part of the circuit

By adding two numbers together in a register and using the sum as the program's final result

By switching the power off and on again so the processor restarts from a different starting point

With a pull-up resistor on the relevant pin, which forces the program down one path or the other

With a conditional branch that tests a value and jumps accordingly

By loading a register with a count and decrementing it to zero in a loop

By adding an external capacitor to the CPU so that it charges slowly and holds the program back

By lowering the supply voltage to the chip, which makes every instruction take noticeably longer

By using more registers at once, since spreading the work across them slows the processor down

The pin voltage is far too high for any motor, so it would immediately burn out the windings

The pin can supply only a small current, far less than a motor needs

The pin output is analogue rather than digital, so it cannot deliver the steady drive a motor needs

Motors need almost no current to run, so the pin actually supplies far more than is ever required

Only switch it on and off in one direction, exactly as a single transistor driver would do

Convert an ordinary DC motor into a stepper motor that can be moved one precise step at a time

Drive it in both directions (and with PWM, control its speed)

Measure the motor's temperature directly so the program can shut it down before it overheats

The motor vibrating on its mountings and shaking the circuit board enough to disturb the readings

A residual ripple voltage left on the supply rails after rectification has not been fully smoothed

A conversion error in the ADC that makes the digitised value drift away from the true input voltage

The contacts making and breaking several times as a switch closes, read as many presses

It senses the actual output and adjusts the drive to reduce the error

It always uses more power than an open-loop system because the sensor and comparator draw current

It has no microcontroller at all, relying instead on fixed analogue circuitry to set the output

It runs without any power supply, drawing the energy it needs from the feedback signal itself

Transformer, rectifier, smoothing, regulation

Input, process, output and power

Resistor, capacitor, diode, transistor

Read, write, branch, loop