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6.4 Microprocessor Control Applications


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Microprocessor Control Applications

Microprocessors (aka Micro-controllers) are tiny computers embedded in household  items, such as televisions, washing machines, burglar alarms and greenhouses. Through the use of input and output connections they can monitor and control the devices in real time.

Features include:

  • Wired / wireless internet connectivity – so that they can be monitored, controlled and updated over the internet.
  • They have a number of input ports, so that they can be connected to buttons and sensors.
  • Output ports, so that they can turn on motors, devices or alarms.
  • The use usually low power devices, meaning they down use a large amount of electricity, especially in standby mode.

Preset Values

Microprocessor control applications often use input sensors with pre-set values – these values are used to control when certain actions will happen.

Glass House

Computer Controlled Glass Houses


  • Temperature sensors
  • Soil moisture level sensors
  • Humidity Sensors


  • Motors to open and close the windows to the glass house in order to control the temperature
  • Motors to pump water from storage containers into the soil to water the plants

Preset Values

  • Thermostat temperature setting to trigger the motors

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Upload to this website to have a look around the Eden project, the largest computer controlled glass house in the world!

Washing Machine

Washing Machines

We don’t think of washing machines as computers, but modern washing machines contain a microprocessor that controls all of the complex washing cycles that modern washing machines have.


  • Water sensors – to check if the watch has drained / has filled to the correct level
  • Temperature sensors – to see if the water has heated up to the required temperature for the wash.
  • Vibration sensors – if the machine is incorrectly loaded and vibrates too much, the machine will switch off to avoid damage to the machine and avoid a potenital leak.


  • Turn on the motors that spin the machine
  • Turn on the draining pumps
  • Turn on the heating coil that heats the water

Preset Values

The dial on the front of the machine has a number of preset values:

  • The washing temperature
  • The cycle type (eco, intense, soak)
  • The spin speed



Automatic Cookers

Automatic cookers are becoming increasingly popular, especially for those people who want to eat quality home-cooked food, but work full-time.

They can be used to cook a variety of meals and foods, including:

  • Slow-cooked stews
  • Pies, Pastries and Bread
  • Rice


  • The cookers have temperature sensors to detect when the cooker has reached the desired temperature


  • The cookers turn on and off the heating elements
  • The cookers often also output a sound or tune when the food has finished cooking

Preset Values

Preset values include:

  • The cooking temperature
  • The programme type ( what type of meal is being cooked)
  • Start time / delay so food only starts cooking at a certain time.


Source: Wikimedia


Burglar Alarms

Burglar alarm systems have become increasingly popular, and now have a vast array of different sensors and control devices.


  • Heat sensors
  • Pressure sensors
  • Infra-red sensors
  • Magnetic reed switches


  • Audio and visual alarms
  • Automatic text / email notifications
  • Automatic police telephone calls
  • Lockdown motors that protect expensive items / rooms

Preset values

  • Arm / disarm times
  • Sensitivity levels – to cope with pets
A PIR sensor attached to a micro-controller and buzzer for output.

A PIR sensor attached to a micro-controller and buzzer for output.

Source – Wikimedia


Central Heating

Central heating systems now include increasingly complex micro-processing units. Modern systems can be controlled via an app on your phone, or even control themselves through location and behavior monitoring.


  • Temperature input
  • Location sensors ( central heating only activates when the owner comes home)


  • Turn on the boiler
  • Close automated windows and vents

Preset Values

  • Temperature setting on the dial
  • Heating on/off times



Activity – Micro-controller Control Application Slides

Create a copy of the Google Slides on the right hand side of this tab. Using the first slide as a template, complete the additional slides.

Note: You must be logged in to Google to make a copy of the slides document.

Click the image for the link.

Click the image for the link.


IPO card sorting activity

Venn diagram style sorting cards where you sort in to Sensor inputs, Preset values, outputs