Project_10934

#include <SoftwareSerial.h>

#define TX_pin    10
#define RX_pin    11
#define Temp_pin  A0
#define Relay_pin 2

SoftwareSerial SIM900A(10, 11);

//--------------------------------------
//These values are in the datasheet
#define RT0 10000   // Ω
#define B 3977      // K
#define VCC 5    //Supply voltage
#define R 10000  //R=10KΩ
//Variables
float RT, VR, ln, TX, T0, VRT;
//--------------------------------------

void setup() {
  pinMode(Relay_pin,OUTPUT);
  pinMode(Temp_pin,INPUT);
  digitalWrite(Relay_pin,LOW);
  SIM900A.begin(9600);
  Serial.begin(9600);    // Setting the baud rate of Serial Monitor (Arduino<--->PC)
  Serial.println ("SIM900A Ready");
  delay(100);
  Serial.println ("Type s to send message or r to receive message");
  SendMessage();
  T0 = 25 + 273.15; //Temperature T0 from datasheet, conversion from Celsius to kelvin
}

void loop() {
  readTemprature();
  if (TX > 50) {
   SendMessage();
    digitalWrite(Relay_pin,LOW);
  }
  else{
    digitalWrite(Relay_pin,HIGH);
  }
  delay(1000);
}

void readTemprature() {
  VRT = analogRead(Temp_pin);        //Acquisition analog value of VRT
  VRT = (5.00 / 1023.00) * VRT;      //Conversion to voltage
  VR = VCC - VRT;
  RT = VRT / (VR / R);               //Resistance of RT
  ln = log(RT / RT0);
  TX = (1 / ((ln / B) + (1 / T0))); //Temperature from thermistor
  TX = TX - 273.15;                 //Conversion to Celsius
  Serial.print("Temperature:");
  Serial.print("\t");
  Serial.print(TX);
  Serial.println("C");
}

void SendMessage()
{
  Serial.println ("Sending Message");
  SIM900A.println("AT+CMGF=1");    //Sets the GSM Module in Text Mode
  delay(1000);
  Serial.println ("Set SMS Number");
  SIM900A.println("AT+CMGS=\"+966542828706\"\r"); //Mobile phone number to send message
  //552480998
  delay(1000);
  Serial.println ("Set SMS Content");
  SIM900A.println("power cut off");// Messsage content
  delay(100);
  Serial.println ("Finish");
  SIM900A.println((char)26);// ASCII code of CTRL+Z
  delay(1000);
  Serial.println ("Message has been sent ->SMS Selesai dikirim");
}