DIY Presence sensor with RCWL-0516 (Radar sensor)

Presence detection is key to a few of my home automations. A few devices such as the TV, Washer, Dryer etc turn on when someone walks into the room. This means I can turn them off when no-one is around (to save energy) and not annoy people too much by having to manually turn them on (via switch or app).

I’ve used a few different motion detectors in the past, ranging from cheap, Chinese motion sensorsto some more advanced multi sensors that also measure temperature/humidity etc.

The problems i’ve found are that they are usually battery powered — so as soon as the battery runs out, the automations stop working and the wife imediately unplugs everything… not idea.

They also tend to be a little unreliable, as they work on line-of-sight they need to be able to see the whole room. 

Anyway, I stumbled across a new (ish) range of sensors that have the amazing advantage of being awesome, and cheap. Like £0.49 cheap.

They work basically as a radar, dectecting motion without around 7m. They can work through walls and other objects, but this does affect their range somewhat. 

I used a Wemos D1 Mini as the micro-controller, as it’s got a cool ESP8266 chip to connect to wifi. I also wanted an excuse to design a custom enclosure using my new 3D printer. A quick Arduino sketch file later and it was talking to my Smartthings instance. I could easily get it connected to an MQTT broker if that’s your thing. Files are at the bottom blink an LED. 

I’ve attached a simple sketch file to get it working, along with the enclosure STL so you can print your own.

Rob StokesComment