Last month, a couple of my Tuya-powered smart plugs stopped being responsive over Wi-Fi. When I checked their Home Assistant activity logs, I discovered that Tuya’s servers caused the hiccups. That felt quite familiar, since every time an expensive smart device from a store troubled me.

In the past few months, I picked up a couple of ESP32 micro-controllers to build my own smart devices to use with Home Assistant. After discovering a bunch of ESP32-based smart home projects, and even building some, has been a game-changer for my smart home.

Any DIY enthusiast who loves tinkering needs to start some ESP32 projects. Many of them turn out to be more useful than any store-bought smart device.

Water level tank monitoring sensor

Never run out of it

One of my neighbors has a store-bought water-level sensor that blares every time their tank fills up, at any hour of the day. But it doesn’t take much to build a DIY water level sensor using an ESP32. You can pick a cheap ultrasonic sensor (JSN-SR04T), which is waterproof, and use it with an ESP32 board to measure the water level.

The ultrasonic sensor sends sonic waves at specified intervals to measure the water level, and the water reacts to those waves' vibrations and responds. Next, pick the graph card to show the water levels in Home Assistant. You can automate this setup to send you an alert when water levels are low, so you can start the water pump, and another automation to turn off the water pump as a safety measure.

DIY smart doorbell

Check before you open the door

Most modern smart doorbells available online or in stores have subscription fees. Like many folks, my colleague Adam Conway didn’t want his video footage sitting on someone else’s server. So he built his own smart doorbell using ESP32 as a Ring alternative. Along with a camera module, he used an ESP32 board, a tiny button, and a power supply.

ESPHome uses YAML-based configuration files to handle all declarations, while Home Assistant does the heavy lifting. Adjust the FPS to a lower setting to keep the setup cool, and add a chime for the doorbell. Whenever someone presses the button, Home Assistant detects the event and plays an audio file of your choice as a bell chime.

Smart alarm clock

Do you remember time?

I always wanted the Lenovo Smart Clock, but looking at the price, I ordered a smart alarm clock from Amazon. It had night mode and a temperature display to justify its smarts. I want to build an ESP32-based smart alarm clock with a buzzer and temperature, but at half the cost.

You can use the MAX7219 8x8 LED dot-matrix modules as a display and program the ESP32 to show the time, temperature, and other details. For audio feedback, plug in a buzzer. Then, flash the YAML configuration using ESPHome code so that even Home Assistant can detect and trigger events based on your alarms and preferences. Of course, using a continuous 5V power source is recommended.

Better presence and motion sensor

Automation becomes easier

A multimodal presence-detection sensor helps support different forms of automation. While the store-bought motion sensors are expensive, you’ll need to make them work with your smart home platform. An ESP32 board paired with an mmWave radar sensor is ideal for building a presence detection system for automation and even security applications.

You can always mix a PIR motion sensor with projects that detect motion using Bluetooth devices and Wi-Fi signal interference. Combining all of them using two ESP32 boards and sensors will still yield a more accurate and useful solution. Of course, you’ll need to prepare the custom firmware to flash on ESP32 boards.

Voice assistant with local LLM support

Works with customizable voice profiles​

I made a private voice assistant while experimenting with different ESP32-based boards in Home Assistant. It works with a local LLM, and I can get just the basics done. However, that setup needs better microphones and speakers to function as a better voice assistant. Also, I wanted to add a wake word to enable hands-free interaction.

You can build your own ESP32-based voice assistant with the ReSpeaker Lite board, which features a two-mic array, an ESP32-S3 mini, and small speakers to build a reliable voice assistant. With powerful hardware, it can process the queries locally. So you can enjoy better integration with Home Assistant, get faster responses, and keep your data on your home network. Meanwhile, big tech’s smart speakers can’t even function without phoning home.

​Start building your own smart home devices

While these are a few cherry-picked examples of ESP32 projects, the rabbit hole goes way deeper. From building a retro-style weather station to your own travel router, ESP32 opens a Pandora’s box of possibilities. That said, adjust your expectations for the ESP32, as it’s a microcontroller at the end of the day, not an SBC. Still, an ESP32 is a better candidate for smart home projects than an SBC like a Raspberry Pi.