Temperature monitor for your fridge or freezer

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Temperature monitor for your fridge or freezer


Do you think it's the same temperature in different places in your fridge or freezer? And how's the freezer functioning, is it freezing properly? Discover the answers to these questions through our IoT project. Using the HARDWARIO Starter Kit, the temperature will be displayed on your mobile phone. ❄

This project will teach you how to measure temperature using IoT. All you need is the basic HARDWARIO Starter Kit.

Prepare the box

  1. Put the Starter Kit together and pair it. If you are doing this for the first time, we’ve prepared a simple guide for you. You need the radio-push-button firmware for the Core Module. If you don't know how to download the firmware or what it is, you can find out more here.
  2. The temperature changes are displayed in the Messages tab in Playground.
HARDWARIO Playground MQTT messages

Set up Node-RED

  1. To see temperature changes, create your own chart using the bubbles in Node-RED. Firstly, click the Functions tab in Playground.
  2. From the Input section, take the light purple MQTT node (bubble) and place it onto the empty desktop.
  3. Double-click the node. In the Topic line specify what you want the colour indicator to display. This now represents temperature. Copy the temperature message from the Messages tab (without a number) to the line. Alternatively, use this:
Node-RED dashboard chart

Confirm by clicking the Done button.

  1. Next to the MQTT node place a second one, this time a blue Chart node. This node can be found in the Dashboard section. This node is used to determine how the measured temperature is displayed on screen. Link both nodes together. 👌
Node-RED chart settings in HARDWARIO Playground
  1. Double-click on the Chart node. In the X-axis line, you can set the period of time the data in the chart will be displayed. This might be, for example, for the duration of your classes. In the Label line, give your chart a name.
Chart in HARDWARIO Playground

Confirm by clicking the Done button.

  1. Now click the Deploy button 🚨 in the top right corner to get everything up and running. ❗ Beware: Every time you change the nodes you have to press Deploy again.
  2. Click on Dashboard. Your temperature chart will be displayed. 👏
MQTT topic

Measure as you please

  1. Now run your own experiments. Which place in your fridge is the coldest? Is it in the top, the middle, or the very bottom? 👌 Is the fridge really cooling as promised by the manufacturer? 🕵️
  2. Try the same in your freezer. Move the box from the bottom to the top. ❓ Try to figure out where to put vegetables, meat or milk. Google what foods need to be kept colder than others. 💡