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AS · Practice questions · Embedded systems, monitoring and control

Sense, compare, act.

Six original Cambridge-style questions on embedded systems and on monitoring and control systems, with mark-scheme style solutions.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
How to earn the marks

Name every link.

01
Recall
[2 marks]

Explain what is meant by an embedded system.

  • A computer system (microprocessor or microcontroller with memory and I/O) built into a larger device. ✓
  • It performs one dedicated function (and usually runs firmware stored in ROM or flash). ✓
02
Explain
[4 marks]

A manufacturer is putting an embedded system into a new smart fridge that connects to the internet. Give two benefits and two drawbacks of using an embedded system.

  • Benefit: small, so it fits inside the fridge (or: cheap to mass-produce). ✓
  • Benefit: low power consumption (or: reliable and fast at its dedicated task; can be controlled remotely). ✓
  • Drawback: difficult to upgrade or repair; may need replacing. ✓
  • Drawback: because it is connected to the internet it could be hacked (or: cannot be used for other tasks). ✓
03
Explain
[2 marks]

Describe the difference between a monitoring system and a control system.

  • A monitoring system uses sensors to measure and record or display data (and may warn), but does not change the conditions. ✓
  • A control system uses the sensor data to change the conditions, by sending signals to actuators. ✓
04
Apply
[5 marks]

A museum keeps the air in a display case at a constant temperature. Describe how a control system using a microprocessor does this.

  • A temperature sensor continuously measures the temperature in the case. ✓
  • The analogue reading is converted to digital by an ADC. ✓
  • The microprocessor compares the reading with pre-set values stored in memory. ✓
  • If it is too low, a signal is sent to an actuator to switch a heater on (if too high, the heater is switched off or a fan/cooler on). ✓
  • The process repeats continuously (feedback). ✓
05
Explain
[2 marks]

Explain why feedback is important in a control system.

  • The output (for example the heater being on) affects the next sensor reading, so the processor can see the effect of its actions. ✓
  • This lets the system adjust automatically and keep conditions within the required limits, without human intervention. ✓
06
Analysis
[3 marks]

A student describes a street-light system as: "The light sensor switches the lamp on when it gets dark." Rewrite the description so that it would earn full marks.

  • The light sensor sends readings (via an ADC) to the microprocessor. ✓
  • The microprocessor compares each reading with a stored pre-set value. ✓
  • If the reading is below the value, the microprocessor sends a signal to the actuator (relay) to switch the lamp on; the process repeats continuously. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.