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How to Check Home Temperature via Cell Phone Using GSM/GPRS Mobile Kit

Difficulty Level: Intermediate -
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Contents

Introduction

This tutorial allows the user to get temperature and control LEDs status sending text messages with the mobile phone. Depending on the text message received by the module, you will be able to turn ON and OFF two LEDs and get the temperature with a sensor.

Ingredients:

    - 1 x GSM/GPRS Mobile Kit:
    • 1x Platform
    • 1x GPRS/GSM QUADBAND MODULE (SIM900)
    • 1x GPRS antenna
    • 2x LEDs
    • 1x Temperature sensor (MCP97004)
    • 2x 220Ω resistors
    • 1x Breadboard
    • 1x External power supply
    • 1x Programming cable
    • Jumper Wires

Preparation Time: 30 minutes

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NOTE: Depending on the platform chosen to develop the project, the ingredients and the schematics shown in this tutorial can vary.

This project can be developed with Arduino or Intel Galileo. It is also compatible with Raspberry Pi using the Raspberry Pi to Arduino shields connection bridge.

For further information about the GPRS/GSM QUADBAND MODULE (SIM900) Shield, consult the main tutorial.

Step 1: Connection

Connect the GPRS antenna to the shield and then, connect the shield to Arduino or to Raspberry Pi connection bridge. Connect the LEDs, the resistors and the temperature sensor in the breadboard as you can see in the next diagram.

Connect two wires, red and black, to the two long rows on the side of the breadboard to provide access to the VCC supply (5V in Arduino and 3.3V in Raspberry Pi) and ground. Then, connect digital pin 9 and 10 to one leg of each resistor. That other leg of the resistor is connected to the cathode (negative leg) of the LED. The other legs of the LEDs (anode) connect to VCC supply. Place the temperature sensor with the flat part looking down like the diagram. Connect the right leg of the sensor to GND and the left to 5 volt. Connect the central leg to the first pin at bottom left of the shield (Analog 0).

WARNING: In Raspberry Pi, GPIO voltage levels are 3.3 V and are not 5 V tolerant. There is no over-voltage protection on the board. Digital inputs use a 3V3 logic level and are not tolerant of 5V levels, such as you might find on a 5V powered Arduino. Extreme caution when working with GPIO, you may damage your Raspberry Pi, your equipment and potentially yourself and others. Doing so is at your own risk!

Step 2: The Code

Arduino:

Code:
/*  
 *  GPRS/GSM Quadband Module (SIM900)
 *  
 *  Copyright (C) Libelium Comunicaciones Distribuidas S.L. 
 *  http://www.libelium.com 
 *  
 *  This program is free software: you can redistribute it and/or modify 
 *  it under the terms of the GNU General Public License as published by 
 *  the Free Software Foundation, either version 3 of the License, or 
 *  (at your option) any later version. 
 *  
 *  This program is distributed in the hope that it will be useful, 
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License 
 *  along with this program.  If not, see http://www.gnu.org/licenses/. 
 *  
 *  Version:           1.0
 *  Design:            David Gascón 
 *  Implementation:    Luis Miguel Martí
 */

#define HEATING 9
#define COOLING 10

//Temperature control
int cnt; //counter
float tdegrees; //
int sensorPin = A0; // input for the thermistor
int sensorValue = 0; // voltage value from voltage divider

int8_t answer;
int x;
int onModulePin = 2;
char SMS[200];
char aux_string[30];
char phone_number[] = "*********"; //phone number to send SMS
char received[200];
char message1[] = {"COOLING ON"};
char message2[] = {"COOLING OFF"};
char message3[] = {"HEATING ON"};
char message4[] = {"HEATING OFF"};
char message5[] = {"TEMP"};
char message6[] = {"Temp: "};
char coma[] = {","};
char deg[] = {" Celsius degrees"};


void setup()   {
  
  pinMode(onModulePin, OUTPUT);
  Serial.begin(115200);

  Serial.println("Starting...");
  power_on();
  delay(3000);
  memset(SMS, 0, sizeof(SMS));
  pinMode(COOLING, OUTPUT);
  pinMode(HEATING, OUTPUT);
  //LED's are controlled with negative logic
  digitalWrite(COOLING, LOW);
  digitalWrite(HEATING, LOW);
  Serial.println("Setting SMS mode...");
  sendATcommand("AT+CMGF=1", "OK", 1000);    // sets the SMS mode to text
  delay(500);
  sendATcommand("AT+CNMI=3,2,0,0", "OK", 1000); //configure new message reception

  digitalWrite(COOLING, HIGH);
  digitalWrite(HEATING, HIGH);

}


void loop()
{
  //wait for the start character
  if (Serial.read() == '+') {
    //read all data
    for (byte i = 0; i < 200; i++) {
      delay(1);
      received[i] = Serial.read();
    }
    byte z = 47;
    //here start the SMS, data before this point are date and time
    while (char(received[z]) != '\n') {
      SMS[z - 47] = received[z];
      Serial.print(SMS[z - 47]);
      z++;
    }
    byte message = checkSMS();

    switch (message) {

      case 0:
        Serial.println("Unknown message!!");
        break;

      case 1:
        Serial.println("Cooling on!");
        digitalWrite(COOLING, LOW);
        break;

      case 2:
        Serial.println("Cooling off!");
        digitalWrite(COOLING, HIGH);
        break;

      case 3:
        Serial.println("Heating on!");
        digitalWrite(HEATING, LOW);
        break;

      case 4:
        Serial.println("Heating off!");
        digitalWrite(HEATING, HIGH);
        break;

      case 5:
        get_temp();
        Serial.println("Sending temp!");
        sendSMS(message6);
        break;

    }
  }

}


void power_on() {

  uint8_t answer = 0;

  // checks if the module is started
  answer = sendATcommand("AT", "OK", 2000);
  if (answer == 0)
  {
    // power on pulse
    digitalWrite(onModulePin, HIGH);
    delay(3000);
    digitalWrite(onModulePin, LOW);

    // waits for an answer from the module
    while (answer == 0) {   // Send AT every two seconds and wait for the answer
      answer = sendATcommand("AT", "OK", 2000);
    }
  }

}

int8_t sendATcommand(char* ATcommand, char* expected_answer, unsigned int timeout) {

  uint8_t x = 0,  answer = 0;
  char response[100];
  unsigned long previous;

  memset(response, '\0', 100);    // Initialice the string

  delay(100);

  while ( Serial.available() > 0) Serial.read();   // Clean the input buffer

  Serial.println(ATcommand);    // Send the AT command


  x = 0;
  previous = millis();

  // this loop waits for the answer
  do {
    // if there are data in the UART input buffer, reads it and checks for the asnwer
    if (Serial.available() != 0) {
      response[x] = Serial.read();
      x++;
      // check if the desired answer is in the response of the module
      if (strstr(response, expected_answer) != NULL)
      {
        answer = 1;
      }
    }
    // Waits for the asnwer with time out
  } while ((answer == 0) && ((millis() - previous) < timeout));

  return answer;
}

void get_temp() {
  tdegrees = analogRead(0)*5/1024.0;
  tdegrees = tdegrees - 0.5;
  tdegrees = tdegrees / 0.01;
  //print all through serial
  Serial.println("Temperature:");
  Serial.print(" ");
  Serial.print(tdegrees);
  Serial.print("C");

}

//this function compares the SMS received with messages declared to know what to do
byte checkSMS() {

  for (byte i = 0; i < sizeof(message1) - 1; i++) {
    if (message1[i] == SMS[i]) {
      if (i == sizeof(message1) - 2) return 1;
    } else i = sizeof(message1);
  }

  for (byte i = 0; i < sizeof(message2) - 1; i++) {
    if (message2[i] == SMS[i]) {
      if (i == sizeof(message2) - 2) return 2;
    } else i = sizeof(message2);
  }

  for (byte i = 0; i < sizeof(message3) - 1; i++) {
    if (message3[i] == SMS[i]) {
      if (i == sizeof(message3) - 2) return 3;
    } else i = sizeof(message3);
  }

  for (byte i = 0; i < sizeof(message4) - 1; i++) {
    if (message4[i] == SMS[i]) {
      if (i == sizeof(message4) - 2) return 4;
    } else i = sizeof(message4);
  }

  for (byte i = 0; i < sizeof(message5) - 1; i++) {
    if (message5[i] == SMS[i]) {
      if (i == sizeof(message5) - 2) return 5;
    } else i = sizeof(message5);
  }

  return 0;

}

void sendSMS(char *mess) {

  sprintf(aux_string, "AT+CMGS=\"%s\"", phone_number); //builds the string to send to the module
  answer = sendATcommand(aux_string, ">", 2000);    // send the SMS number
  if (answer == 1)
  {
    char taux[15];
    dtostrf(tdegrees,5,2,taux);
    sprintf(aux_string, "%s%s%s", mess, taux, deg); //builds the string to send as an SMS
    Serial.println(aux_string);
    Serial.write(0x1A);
    answer = sendATcommand("", "OK", 20000);
    if (answer == 1)
    {
      Serial.print("Sent ");
    }
    else
    {
      Serial.print("error ");
    }
  }
  else
  {
    Serial.print("error ");
    Serial.println(answer, DEC);
  }

}

Raspberry Pi:

Code:
/*  
 *  GPRS/GSM Quadband Module (SIM900)
 *  
 *  Copyright (C) Libelium Comunicaciones Distribuidas S.L. 
 *  http://www.libelium.com 
 *  
 *  This program is free software: you can redistribute it and/or modify 
 *  it under the terms of the GNU General Public License as published by 
 *  the Free Software Foundation, either version 3 of the License, or 
 *  (at your option) any later version. 
 *  
 *  This program is distributed in the hope that it will be useful, 
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License 
 *  along with this program.  If not, see http://www.gnu.org/licenses/. 
 *  
 *  Version:           1.0
 *  Design:            David Gascón 
 *  Implementation:    Marcos Martinez
 */
 
#include "arduPi.h"

#define HEATING 9
#define COOLING 10

//Temperature control
int cnt; //counter
float tdegrees; //
int sensorPin = 0; // input for the thermistor
int sensorValue = 0; // voltage value from voltage divider

int8_t answer;
int x;
int onModulePin = 2;
char SMS[200];
char aux_string[30];
char phone_number[] = "*******"; //phone number to send SMS
char received[200];
char message1[] = {"COOLING ON"};
char message2[] = {"COOLING OFF"};
char message3[] = {"HEATING ON"};
char message4[] = {"HEATING OFF"};
char message5[] = {"TEMP"};
char message6[] = {"Temp: "};
char coma[] = {","};
char deg[] = {" Celsius degrees"};

void power_on();
int8_t sendATcommand(const char* ATcommand, const char* expected_answer, unsigned int timeout);
void get_temp(); 
byte checkSMS();
void sendSMS( char *mess);

void setup()   {
  
  pinMode(onModulePin, OUTPUT);
  Serial.begin(115200);

  printf("Starting...\n");
  power_on();
  delay(3000);
  memset(SMS, 0, sizeof(SMS));
  pinMode(COOLING, OUTPUT);
  pinMode(HEATING, OUTPUT);
  //LED's are controlled with negative logic
  digitalWrite(COOLING, LOW);
  digitalWrite(HEATING, LOW);
  printf("Setting SMS mode...\n");
  sendATcommand("AT+CMGF=1", "OK", 1000);    // sets the SMS mode to text
  delay(500);
  sendATcommand("AT+CNMI=3,2,0,0", "OK", 1000); //configure new message reception

  digitalWrite(COOLING, HIGH);
  digitalWrite(HEATING, HIGH);
	printf("Waiting for a SMS...\n");
}


void loop()
{
  //wait for the start character
  if(Serial.read() == '+'){
	  
    //read all data
    byte i=0;
    
    while(Serial.available()>0){
		
      delay(1);
      received[i] = Serial.read();
      
      i++;
    }
    
    byte z = 47;
    //here start the SMS, data before this point are date and time
    while (char(received[z]) != '\n') {
      SMS[z - 47] = received[z];

      z++;
    }
	printf("SMS received: %s\n", SMS);
    byte message = checkSMS();

    switch (message) {

      case 0:
        printf("Unknown message!!\n");
        break;

      case 1:
        printf("Cooling on!\n");
        digitalWrite(COOLING, LOW);
        break;

      case 2:
        printf("Cooling off!\n");
        digitalWrite(COOLING, HIGH);
        break;

      case 3:
        printf("Heating on!\n");
        digitalWrite(HEATING, LOW);
        break;

      case 4:
        printf("Heating off!\n");
        digitalWrite(HEATING, HIGH);
        break;

      case 5:
        get_temp();
        printf("Sending temp!\n");
        sendSMS(message6);
        break;

    }
  }
  delay(1000);
}


void power_on() {

  uint8_t answer = 0;

  // checks if the module is started
  answer = sendATcommand("AT", "OK", 2000);
  if (answer == 0)
  {
    // power on pulse
    digitalWrite(onModulePin, HIGH);
    delay(3000);
    digitalWrite(onModulePin, LOW);

    // waits for an answer from the module
    while (answer == 0) {   // Send AT every two seconds and wait for the answer
      answer = sendATcommand("AT", "OK", 2000);
    }
  }

}

int8_t sendATcommand(const char* ATcommand, const char* expected_answer, unsigned int timeout) {

  uint8_t x = 0,  answer = 0;
  char response[100];
  unsigned long previous;

  memset(response, '\0', 100);    // Initialice the string

  delay(100);

 

  Serial.println(ATcommand);    // Send the AT command


  x = 0;
  previous = millis();

  // this loop waits for the answer
  do {
    // if there are data in the UART input buffer, reads it and checks for the asnwer
    if (Serial.available() != 0) {
      response[x] = Serial.read();
      printf("%c", response[x]);
      x++;
      // check if the desired answer is in the response of the module
      if (strstr(response, expected_answer) != NULL)
      {
        printf("\n");
        answer = 1;
      }
    }
    // Waits for the asnwer with time out
  } while ((answer == 0) && ((millis() - previous) < timeout));

  return answer;
}

void get_temp() {
  tdegrees = analogRead(0)*5/1024.0;
  tdegrees = tdegrees - 0.5;
  tdegrees = tdegrees / 0.01;
  //print all through serial
  printf("Temperature: %fºC\n", tdegrees);

}

//this function compares the SMS received with messages declared to know what to do
byte checkSMS() {

  for (byte i = 0; i < sizeof(message1) - 1; i++) {
    if (message1[i] == SMS[i]) {
      if (i == sizeof(message1) - 2) return 1;
    } else i = sizeof(message1);
  }

  for (byte i = 0; i < sizeof(message2) - 1; i++) {
    if (message2[i] == SMS[i]) {
      if (i == sizeof(message2) - 2) return 2;
    } else i = sizeof(message2);
  }

  for (byte i = 0; i < sizeof(message3) - 1; i++) {
    if (message3[i] == SMS[i]) {
      if (i == sizeof(message3) - 2) return 3;
    } else i = sizeof(message3);
  }

  for (byte i = 0; i < sizeof(message4) - 1; i++) {
    if (message4[i] == SMS[i]) {
      if (i == sizeof(message4) - 2) return 4;
    } else i = sizeof(message4);
  }

  for (byte i = 0; i < sizeof(message5) - 1; i++) {
    if (message5[i] == SMS[i]) {
      if (i == sizeof(message5) - 2) return 5;
    } else i = sizeof(message5);
  }

  return 0;

}

void sendSMS( char *mess) {

  sprintf(aux_string, "AT+CMGS=\"%s\"", phone_number); //builds the string to send to the module
  answer = sendATcommand(aux_string, ">", 2000);    // send the SMS number
  if (answer == 1)
  {
    //char taux[15];
    //dtostrf(tdegrees,5,2,taux);
    sprintf(aux_string, "%s%f%s", mess, tdegrees, deg); //builds the string to send as an SMS
    Serial.println(aux_string);
    Serial.write(0x1A);
    answer = sendATcommand("", "OK", 20000);
    if (answer == 1)
    {
      printf("Sent \n");
    }
    else
    {
      printf("error \n");
    }
  }
  else
  {
    printf("error %d\n", answer);
  }

}


int main (){
	setup();
	while(1){
		loop();
	}
	return (0);
}

Intel Galileo:

Code:
/*  
 *  GPRS/GSM Quadband Module (SIM900)
 *  
 *  Copyright (C) Libelium Comunicaciones Distribuidas S.L. 
 *  http://www.libelium.com 
 *  
 *  This program is free software: you can redistribute it and/or modify 
 *  it under the terms of the GNU General Public License as published by 
 *  the Free Software Foundation, either version 3 of the License, or 
 *  (at your option) any later version. 
 *  
 *  This program is distributed in the hope that it will be useful, 
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License 
 *  along with this program.  If not, see http://www.gnu.org/licenses/. 
 *  
 *  Version:           1.0
 *  Design:            David Gascón 
 *  Implementation:    Jorge Casanova, Luis Martin
 */
 
#define HEATING 9
#define COOLING 10

//Temperature control
int cnt; //counter
float tdegrees; //
int sensorPin = A0; // input for the thermistor
int sensorValue = 0; // voltage value from voltage divider

int8_t answer;
int x;
int onModulePin = 2;
char SMS[200];
char aux_string[30];
char phone_number[] = "*********"; //phone number to send SMS
char received[200];
char message1[] = {"COOLING ON"};
char message2[] = {"COOLING OFF"};
char message3[] = {"HEATING ON"};
char message4[] = {"HEATING OFF"};
char message5[] = {"TEMP"};
char message6[] = {"Temp: "};
char coma[] = {","};
char deg[] = {" Celsius degrees"};


void setup()   {
  
  pinMode(onModulePin, OUTPUT);
  Serial.begin(115200);
  Serial1.begin(115200);

  Serial.println("Starting...");
  power_on();
  delay(3000);
  memset(SMS, 0, sizeof(SMS));
  pinMode(COOLING, OUTPUT);
  pinMode(HEATING, OUTPUT);
  //LED's are controlled with negative logic
  digitalWrite(COOLING, LOW);
  digitalWrite(HEATING, LOW);
  Serial.println("Setting SMS mode...");
  sendATcommand("AT+CMGF=1", "OK", 1000);    // sets the SMS mode to text
  delay(500);
  sendATcommand("AT+CNMI=3,2,0,0", "OK", 1000); //configure new message reception

  digitalWrite(COOLING, HIGH);
  digitalWrite(HEATING, HIGH);

}


void loop()
{
  //wait for the start character
  if (Serial1.read() == '+') {
    //read all data
    for (byte i = 0; i < 200; i++) {
      delay(1);
      received[i] = Serial1.read();
    }
    byte z = 47;
    //here start the SMS, data before this point are date and time
    while (char(received[z]) != '\n') {
      SMS[z - 47] = received[z];
      Serial.print(SMS[z - 47]);
      z++;
    }
    byte message = checkSMS();

    switch (message) {

      case 0:
        Serial.println("Unknown message!!");
        break;

      case 1:
        Serial.println("Cooling on!");
        digitalWrite(COOLING, LOW);
        break;

      case 2:
        Serial.println("Cooling off!");
        digitalWrite(COOLING, HIGH);
        break;

      case 3:
        Serial.println("Heating on!");
        digitalWrite(HEATING, LOW);
        break;

      case 4:
        Serial.println("Heating off!");
        digitalWrite(HEATING, HIGH);
        break;

      case 5:
        get_temp();
        Serial.println("Sending temp!");
        sendSMS(message6);
        break;

    }
  }

}


void power_on() {

  uint8_t answer = 0;

  // checks if the module is started
  answer = sendATcommand("AT", "OK", 2000);
  if (answer == 0)
  {
    // power on pulse
    digitalWrite(onModulePin, HIGH);
    delay(3000);
    digitalWrite(onModulePin, LOW);

    // waits for an answer from the module
    while (answer == 0) {   // Send AT every two seconds and wait for the answer
      answer = sendATcommand("AT", "OK", 2000);
    }
  }

}

int8_t sendATcommand(char* ATcommand, char* expected_answer, unsigned int timeout) {

  uint8_t x = 0,  answer = 0;
  char response[100];
  unsigned long previous;

  memset(response, '\0', 100);    // Initialice the string

  delay(100);

  while ( Serial1.available() > 0) Serial1.read();   // Clean the input buffer

  Serial1.println(ATcommand);    // Send the AT command


  x = 0;
  previous = millis();

  // this loop waits for the answer
  do {
    // if there are data in the UART input buffer, reads it and checks for the asnwer
    if (Serial1.available() != 0) {
      response[x] = Serial1.read();
      x++;
      // check if the desired answer is in the response of the module
      if (strstr(response, expected_answer) != NULL)
      {
        answer = 1;
      }
    }
    // Waits for the asnwer with time out
  } while ((answer == 0) && ((millis() - previous) < timeout));

  return answer;
}

void get_temp() {
  tdegrees = analogRead(0)*5/1024.0;
  tdegrees = tdegrees - 0.5;
  tdegrees = tdegrees / 0.01;
  //print all through serial
  Serial.println("Temperature:");
  Serial.print(" ");
  Serial.print(tdegrees);
  Serial.print("C");

}

//this function compares the SMS received with messages declared to know what to do
byte checkSMS() {

  for (byte i = 0; i < sizeof(message1) - 1; i++) {
    if (message1[i] == SMS[i]) {
      if (i == sizeof(message1) - 2) return 1;
    } else i = sizeof(message1);
  }

  for (byte i = 0; i < sizeof(message2) - 1; i++) {
    if (message2[i] == SMS[i]) {
      if (i == sizeof(message2) - 2) return 2;
    } else i = sizeof(message2);
  }

  for (byte i = 0; i < sizeof(message3) - 1; i++) {
    if (message3[i] == SMS[i]) {
      if (i == sizeof(message3) - 2) return 3;
    } else i = sizeof(message3);
  }

  for (byte i = 0; i < sizeof(message4) - 1; i++) {
    if (message4[i] == SMS[i]) {
      if (i == sizeof(message4) - 2) return 4;
    } else i = sizeof(message4);
  }

  for (byte i = 0; i < sizeof(message5) - 1; i++) {
    if (message5[i] == SMS[i]) {
      if (i == sizeof(message5) - 2) return 5;
    } else i = sizeof(message5);
  }

  return 0;

}

void sendSMS(char *mess) {

  sprintf(aux_string, "AT+CMGS=\"%s\"", phone_number); //builds the string to send to the module
  answer = sendATcommand(aux_string, ">", 2000);    // send the SMS number
  if (answer == 1)
  {
    //char taux[15];
    //dtostrf(tdegrees,5,2,taux);
    sprintf(aux_string, "%s%f%s", mess, tdegrees, deg); //builds the string to send as an SMS
    Serial1.println(aux_string);
    Serial1.write(0x1A);
    answer = sendATcommand("", "OK", 20000);
    if (answer == 1)
    {
      Serial.print("Sent ");
    }
    else
    {
      Serial.print("error ");
    }
  }
  else
  {
    Serial.print("error ");
    Serial.println(answer, DEC);
  }

}

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