Most ESP32 microcontrollers are blessed with both Bluetooth and Wi-Fi, which means they can be used in a vast number of wireless projects. These could be some of the most useful DIY projects that you ever build.

Here are five to get you started.

Home Assistant Bluetooth proxies

Credit: Adam Davidson/How-To Geek

If you use the Home Assistant smart home platform, you might be interested in adding Bluetooth to your setup. One simple and effective method is to use an ESP32 device that includes both Wi-Fi and Bluetooth Low Energy (which is most of them) in order to extend the range of your server’s Bluetooth capabilities.

These proxies use Wi-Fi as a backbone so that Home Assistant can talk to Bluetooth devices. They’re cheap, at around $5 per board, and don’t require any additional components (or soldering) beyond a standard USB power adapter. The easiest way to do this is to use the Open Home Foundation’s ESPHome firmware, which is natively supported in Home Assistant.

This is great for adding Bluetooth devices anywhere in your home where you already have Wi-Fi. Some devices, like older SwitchBot accessories, rely on Bluetooth for local control. Using a cheap proxy to bridge the gap between your Home Assistant server downstairs and the curtain rail or blind controllers upstairs is a neat solution.

ESP32-based presence detection

Credit: 

Ismar Hrnjicevic / How-To Geek

Bluetooth proxies also enable Bluetooth presence detection. You can use open source projects like ESPresense or Bermuda to track Bluetooth devices (like smartphones, smartwatches, and Bluetooth beacons) that are always with you. This relies on Bluetooth signatures and doesn’t require connecting to a proxy directly.

For example, if you have a Bluetooth tracker on your dog’s collar, you can tell where in the house your dog is hiding. If you want to automatically turn off the lights when everyone leaves the house, you can link this automation to smartphone presence (assuming everyone takes their phones with them).

Choosing between ESPresense and Bermuda is the source of much debate online. Thankfully, it takes minutes to switch between them if you need to do so.

A Bluetooth system monitor for your PC

System monitors are handy tools, but you probably don’t have one on your screen at all times. Even if you do, there are better ways to use that screen real estate. Having a bunch of flickering stats at the top of the screen can be really distracting.

Knowing what your CPU and GPU temperatures are, how fast your fans are spinning, and how much free RAM or disk space you have can be really useful at a glance. So why not build a system monitor that displays this information on a separate screen, which you can put on your desk or mount on your keyboard?

Thankfully, you can build one using an ESP32 development board and a 3.5-inch TFT display, complete with a 3D printed case.

ESP32 Bluetooth receiver or speaker

Credit: Raphael H / Hackaday.io

The actively maintained ESP32-A2DP library is responsible for all manner of Bluetooth audio projects that use the ESP32. It uses the Arduino Software IDE and A2DP Bluetooth protocol to pass along a PCM data stream from a wireless sound source like a smartphone.

If you’re looking for inspiration, check out the library’s show and tell discussion, in which keen makers have shared their creations. For more detailed instructions, you can follow guides like this one on Hackaday.io, instructions for building a complete wireless speaker, or use a custom PCB solution like bop.

3D-printed Stream Deck alternative macropad

Credit: 3Z3D / MakerWorld

Stream Decks are neat devices that allow you to trigger events on your computer with the push of a tactile button. They’re also pretty expensive, since they use small OLED displays that change depending on what you want each button to do. As nice as that is, it’s not essential functionality if all you want is a macropad to fire off specific commands.

Thankfully, you can build your own wireless macropad using an ESP32-C3, some keyboard switches, keycaps, and a jumper wire. MakerWorld user 3Z3D has shared their ESP32 Stream Cheap Deck project, complete with full instructions and 3D printing files. Many who have taken on the project have gone a step further and 3D printed the keycaps too (though you’ll lose that fully transparent look if you do this).

Alternatively, there’s a less polished yet endearing Instructables guide for building a macropad that uses a breadboard and a single OLED display.

Looking for more wireless things to build? Check out last week’s batch of Wi-Fi ESP32 projects.