How to Make Computer on off device at home

Circuit:

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#include <SoftwareSerial.h>

//sender phone number with country code

const String PHONE = "ENTER_YOUR_PHONE_HERE";

//GSM Module RX pin to Arduino 3

//GSM Module TX pin to Arduino 2

#define rxPin 2

#define txPin 3

SoftwareSerial sim800(rxPin,txPin);

#define PC 7

String smsStatus,senderNumber,receivedDate,msg;

boolean isReply = false;

void setup() {

  digitalWrite(PC, HIGH);

  delay(7000);

  Serial.begin(115200);

  Serial.println("Arduino serial initialize");

  sim800.begin(9600);

  Serial.println("SIM800L software serial initialize");

  pinMode(PC, OUTPUT);

  smsStatus = "";

  senderNumber="";

  receivedDate="";

  msg="";

  sim800.print("AT+CMGF=1\r"); //SMS text mode

  delay(1000);

  //delete all sms

  sim800.println("AT+CMGD=1,4");

  delay(1000);

  sim800.println("AT+CMGDA= \"DEL ALL\"");

  delay(1000);

}

void loop() {

//////////////////////////////////////////////////

while(sim800.available()){

  parseData(sim800.readString());

}

//////////////////////////////////////////////////

while(Serial.available()) {

  sim800.println(Serial.readString());

}

//////////////////////////////////////////////////

} //main loop ends

//***************************************************

void parseData(String buff){

  Serial.println(buff);

  unsigned int len, index;

  //////////////////////////////////////////////////

  //Remove sent "AT Command" from the response string.

  index = buff.indexOf("\r");

  buff.remove(0, index+2);

  buff.trim();

  //////////////////////////////////////////////////

  //////////////////////////////////////////////////

  if(buff != "OK"){

    index = buff.indexOf(":");

    String cmd = buff.substring(0, index);

    cmd.trim();

    buff.remove(0, index+2);

    if(cmd == "+CMTI"){

      //get newly arrived memory location and store it in temp

      index = buff.indexOf(",");

      String temp = buff.substring(index+1, buff.length());

      temp = "AT+CMGR=" + temp + "\r";

      //get the message stored at memory location "temp"

      sim800.println(temp);

    }

    else if(cmd == "+CMGR"){

      extractSms(buff);

      if(senderNumber == PHONE){

        doAction();

        //delete all sms

        sim800.println("AT+CMGD=1,4");

        delay(1000);

        sim800.println("AT+CMGDA= \"DEL ALL\"");

        delay(1000);

      }

    }

  //////////////////////////////////////////////////

  }

  else{

  //The result of AT Command is "OK"

  }

}

//************************************************************

void extractSms(String buff){

   unsigned int index;

    index = buff.indexOf(",");

    smsStatus = buff.substring(1, index-1);

    buff.remove(0, index+2);

    senderNumber = buff.substring(0, 13);

    buff.remove(0,19);

    receivedDate = buff.substring(0, 20);

    buff.remove(0,buff.indexOf("\r"));

    buff.trim();

    index =buff.indexOf("\n\r");

    buff = buff.substring(0, index);

    buff.trim();

    msg = buff;

    buff = "";

    msg.toLowerCase();

}

void doAction(){

  if(msg == "pc off"){

    digitalWrite(PC, HIGH);

    delay(50);

    digitalWrite(PC, LOW);

    delay(50);

    Reply("Your PC has been OFF");

  }

  else if(msg == "pc on"){

    digitalWrite(PC, HIGH);

    delay(50);

    digitalWrite(PC, LOW);

    delay(50);

    Reply("Your PC has been ON");

  }

  smsStatus = "";

  senderNumber="";

  receivedDate="";

  msg="";

}

void Reply(String text)

{

    sim800.print("AT+CMGF=1\r");

    delay(1000);

    sim800.print("AT+CMGS=\""+PHONE+"\"\r");

    delay(1000);

    sim800.print(text);

    delay(100);

    sim800.write(0x1A); //ascii code for ctrl-26 //sim800.println((char)26); //ascii code for ctrl-26

    delay(1000);

    Serial.println("SMS Sent Successfully.");

}

Demo Video: