Here is a DIY Arduino Home Security System using an Arduino Mega and ROHM's Sensor Evaluation Kit. The system uses a passive infrared sensor (PIR) sensor to detect any suspicious movement and ROHM's Temperature Sensor (BD1020HFV) and Barometric Pressure Sensor (BM1383GLV) to detect heat. It will be connected to the internet using Arduino WiFi Shield to communicate with Cayenne API.

See the full Part 1 and Part 2 guides.