Use it facing a window to sense when your curtains should open or close. Set an indoor light sensor to trigger doors to close, lock, and various other daytime tools to shut down.

Everything you need to know about setting up an app-controlled, smart lighting system at home, plus five smart lights to get right now.

Smart lights can figure out when you're getting close and automatically turn on. Learn how to make this feature work for you.

Each time the reflective spot passes the beam of the photo-tachometer, some light is reflected back towards the device, where it is picked up by a light sensor.