Circuit Lake

Electronic Project and Circuit Collection

Simple Wireless Security System

08/16/2010 Category: AVR, Digital, Project, Security System, Sensor, Wireless

The Simple Wireless Security System is a security system that includes a ZigBee wireless door sensor and a PC interface. The door sensor mounts near the garage doors, and it detects the open/closed state using reed switches and magnets. The Atmel Attiny45 microcontroller fits in nicely with design because of its small size, low pin count, low cost, and it has a powerful serial interface feature that can be set up as a UART – the required interface for the ZigBee module. When a door opens or closes, the Attiny45 sends a message wirelessly to the PC interface.


The PC interface consists of a standard Windows XP PC and a USB adapter that includes a Zigbee wireless transceiver. The PC runs an application that receives messages from the door sensor and graphically shows the state of the security system by changing its icon in the system tray. Using the PC’s clock, an alert sound is played if the door is open during the middle of the night. The application runs in the “background” while the PC is used for other purposes.

“With the help of the Simple Wireless Security System, I can retire for the evening and not worry about my tools, bikes, and the house entry door from the garage that rarely gets locked. And I have the start of an expandable, customizable whole house security system”, said Steven Nickels, project designer.