Skip to content

Instantly share code, notes, and snippets.

@sarasantos
Last active Nov 2, 2021
Embed
What would you like to do?
// Include Software Serial library to communicate with SIM900
#include <SoftwareSerial.h>
// Configure software serial port
SoftwareSerial SIM900(7, 8);
// Variable to store text message
String textMessage;
// Create a variable to store Lamp state
String lampState = "HIGH";
// Relay connected to pin 12
const int relay = 12;
void setup() {
// Automatically turn on the shield
digitalWrite(9, HIGH);
delay(1000);
digitalWrite(9, LOW);
delay(5000);
// Set relay as OUTPUT
pinMode(relay, OUTPUT);
// By default the relay is off
digitalWrite(relay, HIGH);
// Initializing serial commmunication
Serial.begin(9600);
SIM900.begin(9600);
// Give time to your GSM shield log on to network
delay(20000);
Serial.print("SIM900 ready…");
// AT command to set SIM900 to SMS mode
SIM900.print("AT+CMGF=1\r");
delay(100);
// Set module to send SMS data to serial out upon receipt
SIM900.print("AT+CNMI=2,2,0,0,0\r");
delay(100);
}
void loop(){
if(SIM900.available()>0){
textMessage = SIM900.readString();
Serial.print(textMessage);
delay(10);
}
if(textMessage.indexOf("ON")>=0){
// Turn on relay and save current state
digitalWrite(relay, LOW);
lampState = "on";
Serial.println("Relay set to ON");
textMessage = "";
}
if(textMessage.indexOf("OFF")>=0){
// Turn off relay and save current state
digitalWrite(relay, HIGH);
lampState = "off";
Serial.println("Relay set to OFF");
textMessage = "";
}
if(textMessage.indexOf("STATE")>=0){
String message = "Lamp is " + lampState;
sendSMS(message);
Serial.println("Lamp state resquest");
textMessage = "";
}
}
// Function that sends SMS
void sendSMS(String message){ // AT command to set SIM900 to SMS mode
SIM900.println("AT+CMGF=1");
delay(100);
// REPLACE THE X’s WITH THE RECIPIENT’S MOBILE NUMBER
// USE INTERNATIONAL FORMAT CODE FOR MOBILE NUMBERS
// Send the SMS
SIM900.println("AT+CMGS=\"+33616234297\"");
delay(100);
//Send theSMS
SIM900.println(message);
// End AT command with a ^Z, ASCII code 26
SIM900.write(26);
delay(100);
SIM900.println();
// Give module time to send SMS
delay(5000);
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment