REED click lets you add the tried and tested reed switch to your design.
Even before IoT was all the buzz, an average refrigerator was “smart” enough to know whether it was open or closed. This is thanks to reed sensors, such as the one on this click board.
Think of it as a magnet-activated relay for low current applications. A reed switch is comprised of two tiny strips of magnetic contacts of opposite polarities inside a glass casing.
By default, the two strips don’t touch each other, so the current loop is incomplete and the switch is off. When a magnet comes close (on a closing door, or closing iPad case, or closing old-school clam-shell type cell-phone) the two contacts snap shut, activating the switch. When the magnet is removed (open the door) the strips separate again.