Request Temperature Data Using GSM and Arduino

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Table of Contents

Request Temperature, Project Description:

Request Temperature using GSM– This project is based on the Temperature and Humidity monitoring using a Cell phone, Arduino, and the famous DHT11 Temperature and Humidity Sensor. In this tutorial, you will learn how to request temperature and humidity values from anywhere around the world using your cell phone. There are projects in which the Sensors data is sent after regular intervals, which I believe is not good. This project is different from the rest of the GSM-based projects, as in this project the Temperature and Humidity values are sent only when the owner sends a request message.

Watch the complete video tutorial.

Amazon Links:

Arduino Nano USB-C Type (Recommended)

12v Adaptor:

Sim900A GSM Module:

DC 5V 2A Adaptor

DHT11 Temperature and Humidity Module:

Other Tools and Components:

ESP32 WiFi + Bluetooth Module (Recommended)

Top Arduino Sensors:

Super Starter kit for Beginners

Digital Oscilloscopes

Variable Supply

Digital Multimeter

Soldering iron kits

PCB small portable drill machines

*Please Note: These are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

DHT11 Temperature and Humidity Sensor:

Request Temperature

The DHT11 Temperature and Humidity module have a total of 4 pins, out of which only three pins are used. Pin number 3 is not used. The interfacing of the DHT11 temperature sensor with the Arduino can be seen in the circuit diagram. For the complete explanation, watch the video given at the end.

GSM SIM900A Module:

Request Temperature

This is the GSM module that I will be using in this tutorial, in the market we have different types of GSM modules, the one I will be using today is SIM900A, the same code is also tested on sim900D, so if you want you can also use sim900D.

If you are from Pakistan, Bangladesh or India make sure you purchase the unlocked version of the SIM900A. This GSM SIM900A module the one we will be using in this tutorial, as you can see on the screen has no Onboard voltage regulator, so be careful while applying the voltage. The ideal voltage for this GSM module is 4.7v but you can also connect it with the 5v adaptor.

As the ideal voltage for this GSM module is 4.7v to 5volts, so any voltage above this can damage the GSM module. If you don’t have the regulated 5v adaptor then you can also use an lm317t adjustable voltage regulator. I have a very detailed tutorial on this. Watch the video.

As you can see SIM900A module has so many pins that are clearly labeled but we will be using only 5 of these pins, the power supply pins, GND, RXD 5v, and TXD 5v. The GND of the GSM SIM900A module will be connected with the Arduino GND, TXD of the GSM SIM900A will be connected with the Arduino pin7 and finally, the RXD of the GSM SIM900A module will be connected with the Arduino pin8.

GSM Sim900A and DT11 connections with Arduino:

Request Temperature

For the complete circuit Diagram explanation watch Video tutorial given at the end of this article.

Request temperature data Arduino Programming:

/*
  commands 
  v = feedback request
 */

#include <SoftwareSerial.h> 
#include "DHT.h"

#define DHTPIN 12     // what pin we're connected to

//Uncomment whatever the type of sensor we are using. 
#define DHTTYPE DHT11   // DHT 11 
//#define DHTTYPE DHT22   // DHT 22  (AM2302)
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is 
// pin3 of the sensor is not connected
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor for normal 16mhz Arduino
DHT dht(DHTPIN, DHTTYPE);

char inchar; // Will hold the incoming character from the GSM shield

SoftwareSerial SIM900(8, 7); // gsm module connected here.

String TextForSms ;
String humidity = " Humidity: %";
String temperature = "   Temperature";
String sign = " *C";


void setup() {

   Serial.begin(9600);
  SIM900.begin(9600); // original 19200
   dht.begin();
pinMode(6, OUTPUT);   
digitalWrite(6, HIGH); 
  
//  delay(10000);  // give time to log on to network.
randomSeed(analogRead(0));

  SIM900.print("AT+CMGF=1\r");  // set SMS mode to text
  delay(1000);
  SIM900.print("AT+CNMI=2,2,0,0,0\r"); 
  // blurt out contents of new SMS upon receipt to the GSM shield's serial out
  delay(1000);
     SIM900.println("AT+CMGD=1,4"); // delete all SMS
   delay(5000);
  Serial.println("Ready...");
  
}




void sendSMS(String message)
{
  SIM900.println("AT+CMGF=1\r");                     // AT command to send SMS message
  delay(1000);
 SIM900.println("AT+CMGS = \"+923339218213\"");  // recipient's mobile number, in international format
 
  delay(1000);
  SIM900.println(message);                         // message to send
  delay(1000);
  SIM900.println((char)26);                        // End AT command with a ^Z, ASCII code 26
  delay(1000); 
  SIM900.println();
  delay(1000);                                     // give module time to send SMS
                                   // turn off module
}
void loop() {

if(SIM900.available() == 0)
{

   // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  int h = dht.readHumidity();
  // Read temperature as Celsius
  int t = dht.readTemperature();
  // Read temperature as Fahrenheit
  int f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Compute heat index
  // Must send in temp in Fahrenheit!
  int hi = dht.computeHeatIndex(f, h);

//  Serial.print("Humidity: "); 
//  Serial.print(h);
//  Serial.print(" %\t");
//  Serial.print("Temperature: "); 
//  Serial.print(t);
//  Serial.print(" *C ");
  
  TextForSms = TextForSms + "Humidity: ";
  TextForSms.concat(h);
  TextForSms = TextForSms + "%    Temperature: ";
  TextForSms.concat(t);
  TextForSms = TextForSms + "*C";
  Serial.println(TextForSms);
  delay(2000);
  TextForSms = " ";
  
   if ( t > 40 )
   {
   Serial.println("Temperature Exceeded"); 
TextForSms = " Temperature Exceeded";
 sendSMS(TextForSms);
 delay(5000); 
 TextForSms = ""; 
   }
  
}
  if(SIM900.available() >0)
  {

    inchar=SIM900.read(); 
  Serial.println(inchar);
    delay(20);
    if (inchar=='v')
    {
      delay(10);
 
   Serial.println(inchar);
    
  // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  int h = dht.readHumidity();
  // Read temperature as Celsius
  int t = dht.readTemperature();
  // Read temperature as Fahrenheit
  int f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Compute heat index
  // Must send in temp in Fahrenheit!
  int hi = dht.computeHeatIndex(f, h);

//  Serial.print("Humidity: "); 
//  Serial.print(h);
//  Serial.print(" %\t");
//  Serial.print("Temperature: "); 
//  Serial.print(t);
//  Serial.print(" *C ");
  
  TextForSms = TextForSms + "HUMIDITY: ";
  TextForSms.concat(h);
  TextForSms = TextForSms + "%    TEMPERATURE: ";
  TextForSms.concat(t);
  TextForSms = TextForSms + "*C";
   sendSMS(TextForSms);
  Serial.println(TextForSms);
  delay(2000);
  TextForSms = " ";
    }
 
}


}

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commands

v = feedback request

#include <SoftwareSerial.h>

#include "DHT.h"

#define DHTPIN 12 // what pin we're connected to

//Uncomment whatever the type of sensor we are using.

#define DHTTYPE DHT11 // DHT 11

//#define DHTTYPE DHT22 // DHT 22 (AM2302)

//#define DHTTYPE DHT21 // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V

// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1

// to 3.3V instead of 5V!

// Connect pin 2 of the sensor to whatever your DHTPIN is

// pin3 of the sensor is not connected

// Connect pin 4 (on the right) of the sensor to GROUND

// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor for normal 16mhz Arduino

DHT dht(DHTPIN, DHTTYPE);

char inchar; // Will hold the incoming character from the GSM shield

SoftwareSerial SIM900(8, 7); // gsm module connected here.

String TextForSms ;

String humidity = " Humidity: %";

String temperature = " Temperature";

String sign = " *C";

void setup() {

Serial.begin(9600);

SIM900.begin(9600); // original 19200

dht.begin();

pinMode(6, OUTPUT);

digitalWrite(6, HIGH);

// delay(10000); // give time to log on to network.

randomSeed(analogRead(0));

SIM900.print("AT+CMGF=1\r"); // set SMS mode to text

delay(1000);

SIM900.print("AT+CNMI=2,2,0,0,0\r");

// blurt out contents of new SMS upon receipt to the GSM shield's serial out

delay(1000);

SIM900.println("AT+CMGD=1,4"); // delete all SMS

delay(5000);

Serial.println("Ready...");

}

void sendSMS(String message)

{

SIM900.println("AT+CMGF=1\r"); // AT command to send SMS message

delay(1000);

SIM900.println("AT+CMGS = \"+923339218213\""); // recipient's mobile number, in international format

delay(1000);

SIM900.println(message); // message to send

delay(1000);

SIM900.println((char)26); // End AT command with a ^Z, ASCII code 26

delay(1000);

SIM900.println();

delay(1000); // give module time to send SMS

// turn off module

}

void loop() {

if(SIM900.available() == 0)

{

// Wait a few seconds between measurements.

delay(2000);

// Reading temperature or humidity takes about 250 milliseconds!

// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)

int h = dht.readHumidity();

// Read temperature as Celsius

int t = dht.readTemperature();

// Read temperature as Fahrenheit

int f = dht.readTemperature(true);

// Check if any reads failed and exit early (to try again).

if (isnan(h) || isnan(t) || isnan(f)) {

Serial.println("Failed to read from DHT sensor!");

return;

}

// Compute heat index

// Must send in temp in Fahrenheit!

int hi = dht.computeHeatIndex(f, h);

// Serial.print("Humidity: ");

// Serial.print(h);

// Serial.print(" %\t");

// Serial.print("Temperature: ");

// Serial.print(t);

// Serial.print(" *C ");

TextForSms = TextForSms + "Humidity: ";

TextForSms.concat(h);

TextForSms = TextForSms + "% Temperature: ";

TextForSms.concat(t);

TextForSms = TextForSms + "*C";

Serial.println(TextForSms);

delay(2000);

TextForSms = " ";

if ( t > 40 )

{

Serial.println("Temperature Exceeded");

TextForSms = " Temperature Exceeded";

sendSMS(TextForSms);

delay(5000);

TextForSms = "";

}

if(SIM900.available() >0)

{

inchar=SIM900.read();

Serial.println(inchar);

delay(20);

if (inchar=='v')

{

delay(10);

Serial.println(inchar);

// Wait a few seconds between measurements.

delay(2000);

// Reading temperature or humidity takes about 250 milliseconds!

// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)

int h = dht.readHumidity();

// Read temperature as Celsius

int t = dht.readTemperature();

// Read temperature as Fahrenheit

int f = dht.readTemperature(true);

// Check if any reads failed and exit early (to try again).

if (isnan(h) || isnan(t) || isnan(f)) {

Serial.println("Failed to read from DHT sensor!");

return;

}

// Compute heat index

// Must send in temp in Fahrenheit!

int hi = dht.computeHeatIndex(f, h);

// Serial.print("Humidity: ");

// Serial.print(h);

// Serial.print(" %\t");

// Serial.print("Temperature: ");

// Serial.print(t);

// Serial.print(" *C ");

TextForSms = TextForSms + "HUMIDITY: ";

TextForSms.concat(h);

TextForSms = TextForSms + "% TEMPERATURE: ";

TextForSms.concat(t);

TextForSms = TextForSms + "*C";

sendSMS(TextForSms);

Serial.println(TextForSms);

delay(2000);

TextForSms = " ";

}

Watch Video Tutorial:

Other GSM Related Projects:

How to use GSM and Bluetooth Together To monitor Any Sensors wirelessly using Arduino

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Arduino GSM Project: Security Alert message to multiple numbers

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2 Comments

Kevin Krugielki says:

March 8, 2022 at 7:31 am

Hello,
I’m looking to build a project like this for my Apple Orchard. I would like to have 6 points around my farm to monitor temp and think this project would be perfect. Is this project possible with the parts available now, and workable in the US over our networks. Thank you

inas ch says:

May 21, 2022 at 2:24 am

Hello
good Project ,do You have Simulation in Proteus ? thank you.