Security home alarm that calls cell phone

A GSM home security system alerts you by a phone call when any theft attempt or similar triggering action is sensed by the device. Here a theft attempt or burglar entry is detected by sensing the vibration produced during the action.

This theft alert system can be used for multiple purposes. It can use wherever a theft attempt can be detected by means of vibration. It can be placed on the floor to detect any floor vibration, or to trigger with any machine vibration, or can be placed over lockers, shutters, doors, vehicles etc., to detect any attempts to break, move, damage, etc. This system can also be assembled as a portable module to place, temporarily in shop, office or workplace anywhere as a security device. With this project, you can make your own home protection system, without buying any home security devices.

motion detector that calls cell phone

Refer: GSM module Hardware interface with Arduino

To detect the vibrations the circuit uses a Piezoelectric sensor or PZT transducer. A piezoelectric device generates electrical signals in response to the vibration or applied mechanical force. The analog input value will be in proportional to the intensity of the vibration over the piezo sensor. The electrical signal from the piezoelectric sensor compares with a preset reference (threshold) value. And when the input value is above the threshold, the Arduino executes the AT command sketch. And make a call to the given number.

Change the value of the variable ‘threshold’ to adjust the sensitivity of the device. In the program, the threshold value has already set to 50. The threshold value should be adjusted, so as to trigger the device based on the level of vibration that may be occurred during the theft attempts. A smaller threshold value makes the device to respond even for minute vibrations. So a threshold value should be set to avoid unwanted triggers and to detect wanted triggers.

The piezo sensor should be placed, where the chance of vibration is high or where enough vibration will be produced. For easy and better placing, the sensor can be placed apart from the GSM and Arduino circuit. The wires should not be too long as it may drop the induced voltage. So always try to reduce the wire length as much as possible.

Arduino Code
//GSM call based security system
#include <SoftwareSerial.h>
SoftwareSerial serial(2, 3);// RX, TX
//Set required threshold value.
int threshold = 50;
void setup() {
//Set Exact Baud rate of the GSM/GPRS Module.
void loop() {
 if (analogRead(A0) >= threshold) {
   /*Replace XXXXXXXXXX to 10 digit mobile number & ZZ to 2 digit country code*/

After dialling, there is a delay of 30 seconds before the termination of the call. So, even the call has terminated at the receiver end the next call will be dialled only for a triggering after 30 seconds. That is the device always makes the call alert if any triggering vibration occurs after 30 seconds from the last triggering. To stop the alert completely, the user has to power off the device.

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