This project creates a basic home security system that sends SMS alerts to your phone when motion is detected. The system uses an Arduino Uno, a PIR sensor, and a SIM800L GSM module. It’s ideal for monitoring remote properties, sheds, or workshops without Wi-Fi.<\/p>\n
Difficulty:<\/strong> Intermediate The PIR sensor continuously monitors for motion. When motion is detected, the Arduino activates the GSM module to send a pre-configured SMS to your phone number. The system can also sound a local siren and flash lights as deterrents. An optional keypad or switch can arm\/disarm the system.<\/p>\n The SIM800L operates at 3.3V logic, while Arduino uses 5V. Use a voltage divider on the TX line (Arduino to SIM800L) to reduce voltage:<\/p>\n This SMS-based security system provides reliable intrusion detection without requiring internet connectivity. It’s ideal for remote locations, workshops, or as a backup to your primary security system.<\/p>\n","protected":false},"excerpt":{"rendered":" Project Overview This project creates a basic home security system that sends SMS alerts to your phone when motion is detected. The system uses an Arduino Uno, a PIR sensor, and a SIM800L GSM module. It’s ideal for monitoring remote properties, sheds, or workshops without Wi-Fi. Difficulty: Intermediate Estimated time: 2-3 hours Estimated cost: $25-35 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-3904","post","type-post","status-publish","format-standard","hentry","category-projects"],"blocksy_meta":[],"yoast_head":"\r\n
\nEstimated time:<\/strong> 2-3 hours
\nEstimated cost:<\/strong> $25-35<\/p>\nHow It Works<\/h2>\n
Materials Needed<\/h2>\n
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Circuit Diagram<\/h2>\n
Connection Table<\/h3>\n
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\n \nComponent<\/th>\n Pin<\/th>\n Arduino Pin<\/th>\n<\/tr>\n<\/thead>\n \n PIR Sensor<\/td>\n VCC<\/td>\n 5V<\/td>\n<\/tr>\n \n PIR Sensor<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n \n PIR Sensor<\/td>\n OUT<\/td>\n Digital Pin 2<\/td>\n<\/tr>\n \n SIM800L<\/td>\n VCC<\/td>\n 5V (use external power for reliable operation)<\/td>\n<\/tr>\n \n SIM800L<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n \n SIM800L<\/td>\n TXD<\/td>\n Digital Pin 3 (via voltage divider)<\/td>\n<\/tr>\n \n SIM800L<\/td>\n RXD<\/td>\n Digital Pin 2 (via voltage divider)<\/td>\n<\/tr>\n \n Buzzer<\/td>\n Positive<\/td>\n Digital Pin 8<\/td>\n<\/tr>\n \n Buzzer<\/td>\n Negative<\/td>\n GND<\/td>\n<\/tr>\n \n Status LED<\/td>\n Anode<\/td>\n Digital Pin 13 (through 220\u03a9)<\/td>\n<\/tr>\n \n Status LED<\/td>\n Cathode<\/td>\n GND<\/td>\n<\/tr>\n \n Arming Switch<\/td>\n One pin<\/td>\n Digital Pin 7<\/td>\n<\/tr>\n \n Arming Switch<\/td>\n Other pin<\/td>\n GND<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Important: SIM800L Voltage Levels<\/h3>\n
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Arduino Code<\/h2>\n
#include <SoftwareSerial.h>\n\n\/\/ Pin definitions\nconst int pirPin = 2;\nconst int buzzerPin = 8;\nconst int ledPin = 13;\nconst int armPin = 7;\n\n\/\/ GSM module\nSoftwareSerial gsm(3, 2); \/\/ RX, TX\n\n\/\/ Configuration\nconst char* phoneNumber = \"+1234567890\"; \/\/ Replace with your number\nbool armed = true; \/\/ Start armed\nbool alarmTriggered = false;\nunsigned long alarmStartTime = 0;\nconst unsigned long alarmDuration = 30000; \/\/ Siren on for 30 seconds\n\nvoid setup() {\n Serial.begin(9600);\n gsm.begin(9600);\n \n pinMode(pirPin, INPUT);\n pinMode(buzzerPin, OUTPUT);\n pinMode(ledPin, OUTPUT);\n pinMode(armPin, INPUT_PULLUP);\n \n digitalWrite(buzzerPin, LOW);\n digitalWrite(ledPin, LOW);\n \n Serial.println(\"Security System Starting...\");\n Serial.println(\"Waiting 60 seconds for PIR warm-up...\");\n delay(60000);\n \n \/\/ Initialize GSM module\n Serial.println(\"Initializing GSM...\");\n sendATCommand(\"AT\", 1000);\n sendATCommand(\"AT+CMGF=1\", 1000); \/\/ Text mode\n sendATCommand(\"AT+CNMI=2,2,0,0,0\", 1000); \/\/ New SMS indication\n \n Serial.println(\"System Ready\");\n digitalWrite(ledPin, HIGH); \/\/ LED on when armed\n}\n\nvoid sendATCommand(String cmd, int timeout) {\n gsm.println(cmd);\n delay(timeout);\n while (gsm.available()) {\n Serial.write(gsm.read());\n }\n}\n\nvoid sendSMS(String message) {\n Serial.println(\"Sending SMS...\");\n gsm.print(\"AT+CMGS=\\\"\");\n gsm.print(phoneNumber);\n gsm.println(\"\\\"\");\n delay(500);\n gsm.print(message);\n delay(500);\n gsm.write(26); \/\/ Ctrl+Z to send\n delay(3000);\n Serial.println(\"SMS sent\");\n}\n\nvoid triggerAlarm() {\n if (!alarmTriggered && armed) {\n alarmTriggered = true;\n alarmStartTime = millis();\n \n Serial.println(\"ALARM TRIGGERED!\");\n \n \/\/ Send SMS\n sendSMS(\"ALERT: Motion detected at your property!\");\n \n \/\/ Sound siren\n digitalWrite(buzzerPin, HIGH);\n \n \/\/ Flash LED\n for (int i = 0; i < 10; i++) {\n digitalWrite(ledPin, LOW);\n delay(200);\n digitalWrite(ledPin, HIGH);\n delay(200);\n }\n }\n}\n\nvoid resetAlarm() {\n alarmTriggered = false;\n digitalWrite(buzzerPin, LOW);\n if (armed) {\n digitalWrite(ledPin, HIGH);\n } else {\n digitalWrite(ledPin, LOW);\n }\n Serial.println(\"Alarm reset\");\n}\n\nvoid loop() {\n \/\/ Check arming status\n bool newArmed = digitalRead(armPin) == LOW;\n if (newArmed != armed) {\n armed = newArmed;\n if (armed) {\n Serial.println(\"System ARMED\");\n digitalWrite(ledPin, HIGH);\n sendSMS(\"Security system ARMED\");\n } else {\n Serial.println(\"System DISARMED\");\n digitalWrite(ledPin, LOW);\n resetAlarm();\n sendSMS(\"Security system DISARMED\");\n }\n delay(500); \/\/ Debounce\n }\n \n \/\/ Check motion\n bool motion = digitalRead(pirPin) == HIGH;\n if (motion && armed && !alarmTriggered) {\n triggerAlarm();\n }\n \n \/\/ Auto-reset alarm after duration\n if (alarmTriggered && (millis() - alarmStartTime > alarmDuration)) {\n resetAlarm();\n }\n \n delay(100);\n}\n<\/code><\/pre>\nTesting the System<\/h2>\n
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Installation Steps<\/h2>\n
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Troubleshooting<\/h2>\n
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Project Extensions<\/h2>\n
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Conclusion<\/h2>\n