Introduction

In this article, I will provide a step-by-step guide on how to build your own touch-screen thermostat using an Arduino microcontroller and basic electronic components for less than $40.

A thermostat allows you to control the temperature of your home or office automatically. Purchasing a smart thermostat from a store can be expensive, with prices ranging from $100 to $250. However, with some basic electronics knowledge and components, you can build your own DIY touch-screen thermostat with an Arduino that will cost a fraction of a commercial product.

The total cost to build this DIY touch-screen thermostat will be around $30 to $40. This is significantly cheaper than buying a pre-made smart thermostat. Additionally, this project is fully customizable - you can tweak it to suit your specific needs.

Below I will cover:

By the end of this guide you will have your own Arduino-based touch-screen thermostat that can control your home's HVAC system automatically!

Required Components

The components required for this DIY touch-screen thermostat build are:

Optional components include:

So as you can see, the total cost is under $40 for all required components. The main costs are the Arduino Uno board and the touch-screen display.

For tools, you will need:

Now let's look at how to put together the circuit.

Circuit Diagram

Here is the circuit diagram showing how to connect all of the components:

How to Build a DIY Touch-Screen Thermostat with Arduino for Under

The key points are:

I recommend first prototyping the circuit on a breadboard before soldering it together.

Loading the Arduino Code

To program the Arduino Uno, you will need to download the Arduino IDE on your computer. Then download the Arduino thermostat code from GitHub:

https://github.com/johnshopkins/diy-thermostat

The code includes all of the touch-screen and temperature control logic needed for the thermostat. You will just need to customize the temperature ranges and HVAC pin number for your specific setup.

Here are the key elements of the code:

After customizing the code, simply upload it to the Arduino board through the Arduino IDE.

Setting up the Touch Screen

The 2.4" TFT touch screen will plug directly into the Arduino. The touch sensitivity can be calibrated by uploading the included touch screen calibration sketch.

Once calibrated, the display will show the home screen with buttons to change the set temperature up/down, as well as show the current temperature and time. All interaction will happen directly on the touch screen.

Programming the Thermostat Logic

The Arduino code includes a Thermostat class that handles the core temperature regulation logic. Here is the overview:

This allows the thermostat to maintain the target set temperature by controlling your HVAC system.

Additional logic is included for:

All of the logic is customizable by modifying the Arduino sketch.

Installing and Setting up the Thermostat

Once the hardware and software is ready, you need to install the DIY Arduino thermostat. Here are the steps:

  1. Mount the thermostat on the wall with the display at eye level
  2. Connect the relay module to control your HVAC system
  3. Power on the Arduino with the power supply
  4. Verify the thermostat is maintaining the set temperature

The thermostat will automatically load the touch screen interface on power up. You can then use the up/down buttons to adjust target temperature.

To improve accuracy, place the DS18B20 temperature sensor away from direct sunlight and drafts. Position it on an inner wall if possible.

And that's it! You now have your own customized DIY touch screen thermostat with Arduino to control your home's heating and cooling automatically. Let me know if you have any other questions!