The Stealthy Smart Home

I love tech gadgets as much as anyone. Seeing an old, unloved computer or video game console sitting on the shelf of a second-hand shop makes me as sad as those commercials about stray dogs that need $20 per month to find a home. Under no circumstances will I leave that store without a pile of “new” gear. Even so, living in a house that looks like a Best Buy is not my idea of aesthetic perfection.

I know I’m not the only one who feels this way, because lots of people are working hard to make their smart home equipment disappear into the background of their homes. Dillan Stock, for instance, recently hacked together some custom sensors that fit inside of his doors to make them totally invisible. Since then, Stock has been working on invisible human presence sensors. These sensors are hidden inside pots of houseplants so that you don’t have any little white boxes cluttering up your space.

Stock began by creating a 3D-printed pot. Hidden inside is a millimeter wave (mmWave) radar sensor capable of detecting the tiny movements caused by human breathing. Unlike the simpler PIR motion sensors found in many smart homes, mmWave sensors can tell if somebody is still in the room even when they aren’t moving around. That means your lights no longer shut off just because you stopped waving your arms while watching TV.

The specific hardware used is an Apollo MTR-1, an ESP32-based board that includes mmWave radar along with optional environmental monitoring features like temperature and CO2 sensing. Since mmWave radar can see directly through plastic, the electronics can remain completely hidden inside the pot without affecting performance.

The MTR-1 has an exposed GPIO header for interfacing with external hardware, but as designed, it adds too much bulk for Stock’s project. To fix this, he designed a custom breakout board that connects to the sensor’s expansion port, allowing additional hardware to be neatly integrated into the build. This enabled the addition of an addressable RGBW LED ring that was mounted around the rim of the pot. Using these LEDs, the planter can double as a tasteful accent lamp.

Of course, putting electronics inside something that regularly gets filled with dirt and water introduces some obvious challenges. To waterproof the planter, Stock coated the inside of the 3D print with UV-cured resin, sealing the naturally porous plastic and protecting the internal electronics from leaks. Venting built into the bottom section still allows airflow so the environmental sensors can continue providing accurate readings.

The entire system runs on ESPHome firmware, making it easy to integrate with existing smart home setups. In Stock’s own home, the pot changes color depending on the status of his solar battery system, glowing green when excess energy is available and red when power reserves are running low.

If you’re fed up with the way commercial smart home equipment looks, you might want to consider taking a DIY approach. Following Stock’s method is as good a way as any to get started.