Store Arduino data to Firebase database

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    Featured image

    Description
    Imagine that you have a simple temperature sensor that measures the boiler’s water temperature every few minutes and you want to keep a history log of it in order to make some adjustments to thermostat. If you also want those measurements to be available online so you will be able to access them at any time then each sensor reading has to be stored somewhere.

    The Firebase lets you connect to your own Firebase database and do  all the CRUD operations through simple calls to their api. You can visit their website and they will give you a 100Mb database free. Firebase uses only HTTPS for security reasons.

     

    Hardware Connection

    DS18S20_arduino-660x391

    The DS1820 temperature sensor is connected to the arduino as shown in the figure. We are also using a Arduino Ethernet Shield; a prototyping board of Wiznet chip W5100.

    The following picture shows the completed hardware connection:

    Featured image

     

    Firebase Connection

    Next step is to create your free firebase database in https://firebase.google.com/ .

    Then log into the database and go at the last menu item “Secrets”. From there you will get your secret token. Write it down as we will need it later. So now we have the hardware and the database ready. If you dont already have a domain, or sub domain go get one from your favorite registar and host the Firebase php library file in one of the thousand hosting providers that offer free plans.

    Here, windows azure account is used and created a new website. Then by ftp the firebaseLib.php  is uploaded.

    <?php
 
/**
 * Firebase PHP Client Library
 *
 * @author Tamas Kalman <ktamas77@gmail.com>
 * @link   https://www.firebase.com/docs/rest-api.html
 *
 */
 
/**
 * Firebase PHP Class
 *
 * @author Tamas Kalman <ktamas77@gmail.com>
 * @link   https://www.firebase.com/docs/rest-api.html
 *
 */
class Firebase
{
 
    private $_baseURI;
    private $_timeout;
    private $_token;
 
    /**
     * Constructor
     *
     * @param String $baseURI Base URI
     *
     * @return void
     */
    function __construct($baseURI = '', $token = '')
    {
        if (!extension_loaded('curl')) {
            trigger_error('Extension CURL is not loaded.', E_USER_ERROR);
        }
 
        $this->setBaseURI($baseURI);
        $this->setTimeOut(10);
        $this->setToken($token);
    }
 
    /**
     * Sets Token
     *
     * @param String $token Token
     *
     * @return void
     */
    public function setToken($token)
    {
        $this->_token = $token;
    }
 
    /**
     * Sets Base URI, ex: http://yourcompany.firebase.com/youruser
     *
     * @param String $baseURI Base URI
     *
     * @return void
     */
    public function setBaseURI($baseURI)
    {
        $baseURI .= (substr($baseURI, -1) == '/' ? '' : '/');
        $this->_baseURI = $baseURI;
    }
 
    /**
     * Returns with the normalized JSON absolute path
     *
     * @param String $path to data
     */
    private function _getJsonPath($path)
    {
        $url = $this->_baseURI;
        $path = ltrim($path, '/');
        $auth = ($this->_token == '') ? '' : '?auth=' . $this->_token;
        return $url . $path . '.json' . $auth;
    }
 
    /**
     * Sets REST call timeout in seconds
     *
     * @param Integer $seconds Seconds to timeout
     *
     * @return void
     */
    public function setTimeOut($seconds)
    {
        $this->_timeout = $seconds;
    }
 
    /**
     * Writing data into Firebase with a PUT request
     * HTTP 200: Ok
     *
     * @param String $path Path
     * @param Mixed  $data Data
     *
     * @return Array Response
     */
    public function set($path, $data)
    {
      return $this->_writeData($path, $data, 'PUT');
    }
 
    /**
     * Pushing data into Firebase with a POST request
     * HTTP 200: Ok
     *
     * @param String $path Path
     * @param Mixed  $data Data
     *
     * @return Array Response
     */
    public function push($path, $data)
    {
      return $this->_writeData($path, $data, 'POST');
    }
 
    /**
     * Updating data into Firebase with a PATH request
     * HTTP 200: Ok
     *
     * @param String $path Path
     * @param Mixed  $data Data
     *
     * @return Array Response
     */
    public function update($path, $data)
    {
      return $this->_writeData($path, $data, 'PATCH');
    }
 
    /**
     * Reading data from Firebase
     * HTTP 200: Ok
     *
     * @param String $path Path
     *
     * @return Array Response
     */
    public function get($path)
    {
        try {
            $ch = $this->_getCurlHandler($path, 'GET');
            $return = curl_exec($ch);
            curl_close($ch);
        } catch (Exception $e) {
            $return = null;
        }
        return $return;
    }
 
    /**
     * Deletes data from Firebase
     * HTTP 204: Ok
     *
     * @param type $path Path
     *
     * @return Array Response
     */
    public function delete($path)
    {
        try {
            $ch = $this->_getCurlHandler($path, 'DELETE');
            $return = curl_exec($ch);
            curl_close($ch);
        } catch (Exception $e) {
            $return = null;
        }
        return $return;
    }
 
    /**
     * Returns with Initialized CURL Handler
     *
     * @param String $mode Mode
     *
     * @return CURL Curl Handler
     */
    private function _getCurlHandler($path, $mode)
    {
        $url = $this->_getJsonPath($path);
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_TIMEOUT, $this->_timeout);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $this->_timeout);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $mode);
        return $ch;
    }
 
    private function _writeData($path, $data, $method = 'PUT')
    {
        $jsonData = json_encode($data);
        $header = array(
            'Content-Type: application/json',
            'Content-Length: ' . strlen($jsonData)
        );
        try {
            $ch = $this->_getCurlHandler($path, $method);
            curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonData);
            $return = curl_exec($ch);
            curl_close($ch);
        } catch (Exception $e) {
            $return = null;
        }
        return $return;
    }
 
}

     

    And now the most importand file that you also have to upload to your hosting directory. Its the file that will respond to Arduino requests.

    <?php
require_once 'firebaseLib.php';
// --- This is your Firebase URL
$url = 'https://xxxxxx.firebaseio.com/';
// --- Use your token from Firebase here
$token = 'xxxxxxxxxxxxxxx';
// --- Here is your parameter from the http GET
$arduino_data = $_GET['arduino_data'];
// --- $arduino_data_post = $_POST['name'];
// --- Set up your Firebase url structure here
$firebasePath = '/';
/// --- Making calls
$fb = new fireBase($url, $token);
$response = $fb->push($firebasePath, $arduino_data);
sleep(2);

    So now if you do a manual request to http://www.yourdomain.com/firbaseTest.php?arduino_data=21.00 the value 21.00 should be stored in your firebase database.

     

    Now the only thing that is left is to make the Arduino send the actually readings. So instead of the dummy “21.00” that we put manually before we will have the real temp readings.  The arduino code is this one:

    #include <SPI.h>
#include <Ethernet.h>
#include <OneWire.h> 
 
int DS18S20_Pin = 2;
OneWire ds(DS18S20_Pin);  // on digital pin 2
 
// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
char serverName[] = "ardufirebase.azurewebsites.net";    // name address of your domain
 
// Set the static IP address to use if the DHCP fails to assign
IPAddress ip(192,168,0,177);
int serverPort = 80;
EthernetClient client;
int totalCount = 0;
char pageAdd[64];
 
char tempString[] = "00.00";
 
// set this to the number of milliseconds delay
// this is 5 seconds
#define delayMillis 5000UL
 
unsigned long thisMillis = 0;
unsigned long lastMillis = 0;
 
void setup() {
  Serial.begin(9600);
 
  // disable SD SPI
  pinMode(4,OUTPUT);
  digitalWrite(4,HIGH);
 
  // Start ethernet
  Serial.println(F("Starting ethernet..."));
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    // try to congifure using IP address instead of DHCP:
    Ethernet.begin(mac, ip);
  }
 
  digitalWrite(10,HIGH);
 
  Serial.println(Ethernet.localIP());
 
  delay(2000);
  Serial.println(F("Ready"));
}
 
void loop()
{  
  thisMillis = millis();
 
  if(thisMillis - lastMillis > delayMillis)
  {
    lastMillis = thisMillis;
 
    float temperature = getTemp();
    Serial.println(ftoa(tempString,temperature,2));
    sprintf(pageAdd,"/firebaseTest.php?arduino_data=%s",ftoa(tempString,temperature,2));
    if(!getPage(serverName,serverPort,pageAdd)) Serial.print(F("Fail "));
    else Serial.print(F("Pass "));
    totalCount++;
    Serial.println(totalCount,DEC);
  }    
}
 
byte getPage(char *ipBuf,int thisPort, char *page)
{
  int inChar;
  char outBuf[128];
 
  Serial.print(F("connecting..."));
 
  if(client.connect(ipBuf,thisPort))
  {
    Serial.println(F("connected"));
 
    sprintf(outBuf,"GET %s HTTP/1.1",page);
    client.println(outBuf);
    sprintf(outBuf,"Host: %s",serverName);
    client.println(outBuf);
    client.println(F("Connection: close\r\n"));
  } 
  else
  {
    Serial.println(F("failed"));
    return 0;
  }
 
  // connectLoop controls the hardware fail timeout
  int connectLoop = 0;
 
  while(client.connected())
  {
    while(client.available())
    {
      inChar = client.read();
      Serial.write(inChar);
      // set connectLoop to zero if a packet arrives
      connectLoop = 0;
    }
 
    connectLoop++;
 
    // if more than 10000 milliseconds since the last packet
    if(connectLoop > 10000)
    {
      // then close the connection from this end.
      Serial.println();
      Serial.println(F("Timeout"));
      client.stop();
    }
    // this is a delay for the connectLoop timing
    delay(1);
  }
 
  Serial.println();
 
  Serial.println(F("disconnecting."));
  // close client end
  client.stop();
 
  return 1;
}
 
float getTemp(){
  //returns the temperature from one DS18S20 in DEG Celsius
 
  byte data[12];
  byte addr[8];
 
  if ( !ds.search(addr)) {
      //no more sensors on chain, reset search
      ds.reset_search();
      return -1000;
  }
 
  if ( OneWire::crc8( addr, 7) != addr[7]) {
      Serial.println("CRC is not valid!");
      return -1000;
  }
 
  if ( addr[0] != 0x10 && addr[0] != 0x28) {
      Serial.print("Device is not recognized");
      return -1000;
  }
 
  ds.reset();
  ds.select(addr);
  ds.write(0x44,1); // start conversion, with parasite power on at the end
 
  byte present = ds.reset();
  ds.select(addr);    
  ds.write(0xBE); // Read Scratchpad
 
  for (int i = 0; i < 9; i++) { // we need 9 bytes
    data[i] = ds.read();
  }
 
  ds.reset_search();
 
  byte MSB = data[1];
  byte LSB = data[0];
 
  float tempRead = ((MSB << 8) | LSB); //using two's compliment
  float TemperatureSum = tempRead / 16;
 
  return TemperatureSum;
 
}
 
char *ftoa(char *a, double f, int precision)
{
  long p[] = {0,10,100,1000,10000,100000,1000000,10000000,100000000};  
  char *ret = a;
  long heiltal = (long)f;
  itoa(heiltal, a, 10);
  while (*a != '\0') a++;
  *a++ = '.';
  long desimal = abs((long)((f - heiltal) * p[precision]));
  itoa(desimal, a, 10);
  return ret;
}

    Here we used parts of the web client example code from arduino.cc. So in a few words what we are doing is we are making a request and we pass the current temperature reading. It is set to do the request every 5 seconds. The most difficult part for was to convert the float value in string.

     

    Here is a video:

    Here we are creating a simple html file and with some javascript and a jquery chart plugin and just showing the current temperature from the  room and a graph of it.

    The index html:

    <html>
	<head>
		<script type='text/javascript' src='https://cdn.firebase.com/js/client/1.0.6/firebase.js'></script>		
		<script language="javascript" type="text/javascript" src="http://code.jquery.com/jquery-2.1.0.min.js"></script>
		<script type="text/javascript" src="http://people.iola.dk/olau/flot/jquery.flot.js"></script>
		<script src="controller.js"></script>
		<link rel="stylesheet" type="text/css" href="bootstrap.min.css" />
	</head>
	<body>
		<div style="width:800px; margin:0 auto;">
			<div><h1 id='tempMsg' style='display:none;width:550px; margin:0 auto;margin-top: 50px;'>Current temp: <span id="currTemp"></span>&deg;C</h1></div>
			<div id="chart1" style="width:600px;height:300px;"></div> 
		</div>
	</body>
	<footer></footer>
</html>

    And the javascript file (controller.js)

    $(document).ready(function() {
	var tempsArray = [];
	var tArray = [];
	var sessionArray = [];
	var currTemp = '';
 
	var dataRef = new Firebase('https://arduino-test.firebaseio.com');
	dataRef.on('value', function(snapshot) {
		var t = snapshot.val();
		var count = 0;
 
		for (var key in t) {
		  if (t.hasOwnProperty(key)) {		    
		    var dt = [];	    
		    dt[0] = count;
		    dt[1] = parseFloat(t[key]);
		    tempsArray = [];
		    tempsArray.push(dt);
		    tArray = [];
		    tArray.push(dt[1]);
		    count++;
		  }
		}
		sessionArray.push(tempsArray[0])
		//console.log(tempsArray)
		$.plot($("#chart1"), [ sessionArray ]);
		currTemp = tempsArray[0][1].toString();
		$('#tempMsg').show();
		$("#currTemp").text(currTemp);
	});			
});

     

    Sample Graph

     

    Source URL: http://www.devacron.com/arduino-firebase/ 

    Tags: 201802, W5100, Ethernet, Arduino, database, ds1820, Firebase

    Featured image

    Description
    Imagine that you have a simple temperature sensor that measures the boiler’s water temperature every few minutes and you want to keep a history log of it in order to make some adjustments to thermostat. If you also want those measurements to be available online so you will be able to access them at any time then each sensor reading has to be stored somewhere.

    The Firebase lets you connect to your own Firebase database and do  all the CRUD operations through simple calls to their api. You can visit their website and they will give you a 100Mb database free. Firebase uses only HTTPS for security reasons.

     

    Hardware Connection

    DS18S20_arduino-660x391

    The DS1820 temperature sensor is connected to the arduino as shown in the figure. We are also using a Arduino Ethernet Shield; a prototyping board of Wiznet chip W5100.

    The following picture shows the completed hardware connection:

    Featured image

     

    Firebase Connection

    Next step is to create your free firebase database in https://firebase.google.com/ .

    Then log into the database and go at the last menu item “Secrets”. From there you will get your secret token. Write it down as we will need it later. So now we have the hardware and the database ready. If you dont already have a domain, or sub domain go get one from your favorite registar and host the Firebase php library file in one of the thousand hosting providers that offer free plans.

    Here, windows azure account is used and created a new website. Then by ftp the firebaseLib.php  is uploaded.

    <?php
 
/**
 * Firebase PHP Client Library
 *
 * @author Tamas Kalman <ktamas77@gmail.com>
 * @link   https://www.firebase.com/docs/rest-api.html
 *
 */
 
/**
 * Firebase PHP Class
 *
 * @author Tamas Kalman <ktamas77@gmail.com>
 * @link   https://www.firebase.com/docs/rest-api.html
 *
 */
class Firebase
{
 
    private $_baseURI;
    private $_timeout;
    private $_token;
 
    /**
     * Constructor
     *
     * @param String $baseURI Base URI
     *
     * @return void
     */
    function __construct($baseURI = '', $token = '')
    {
        if (!extension_loaded('curl')) {
            trigger_error('Extension CURL is not loaded.', E_USER_ERROR);
        }
 
        $this->setBaseURI($baseURI);
        $this->setTimeOut(10);
        $this->setToken($token);
    }
 
    /**
     * Sets Token
     *
     * @param String $token Token
     *
     * @return void
     */
    public function setToken($token)
    {
        $this->_token = $token;
    }
 
    /**
     * Sets Base URI, ex: http://yourcompany.firebase.com/youruser
     *
     * @param String $baseURI Base URI
     *
     * @return void
     */
    public function setBaseURI($baseURI)
    {
        $baseURI .= (substr($baseURI, -1) == '/' ? '' : '/');
        $this->_baseURI = $baseURI;
    }
 
    /**
     * Returns with the normalized JSON absolute path
     *
     * @param String $path to data
     */
    private function _getJsonPath($path)
    {
        $url = $this->_baseURI;
        $path = ltrim($path, '/');
        $auth = ($this->_token == '') ? '' : '?auth=' . $this->_token;
        return $url . $path . '.json' . $auth;
    }
 
    /**
     * Sets REST call timeout in seconds
     *
     * @param Integer $seconds Seconds to timeout
     *
     * @return void
     */
    public function setTimeOut($seconds)
    {
        $this->_timeout = $seconds;
    }
 
    /**
     * Writing data into Firebase with a PUT request
     * HTTP 200: Ok
     *
     * @param String $path Path
     * @param Mixed  $data Data
     *
     * @return Array Response
     */
    public function set($path, $data)
    {
      return $this->_writeData($path, $data, 'PUT');
    }
 
    /**
     * Pushing data into Firebase with a POST request
     * HTTP 200: Ok
     *
     * @param String $path Path
     * @param Mixed  $data Data
     *
     * @return Array Response
     */
    public function push($path, $data)
    {
      return $this->_writeData($path, $data, 'POST');
    }
 
    /**
     * Updating data into Firebase with a PATH request
     * HTTP 200: Ok
     *
     * @param String $path Path
     * @param Mixed  $data Data
     *
     * @return Array Response
     */
    public function update($path, $data)
    {
      return $this->_writeData($path, $data, 'PATCH');
    }
 
    /**
     * Reading data from Firebase
     * HTTP 200: Ok
     *
     * @param String $path Path
     *
     * @return Array Response
     */
    public function get($path)
    {
        try {
            $ch = $this->_getCurlHandler($path, 'GET');
            $return = curl_exec($ch);
            curl_close($ch);
        } catch (Exception $e) {
            $return = null;
        }
        return $return;
    }
 
    /**
     * Deletes data from Firebase
     * HTTP 204: Ok
     *
     * @param type $path Path
     *
     * @return Array Response
     */
    public function delete($path)
    {
        try {
            $ch = $this->_getCurlHandler($path, 'DELETE');
            $return = curl_exec($ch);
            curl_close($ch);
        } catch (Exception $e) {
            $return = null;
        }
        return $return;
    }
 
    /**
     * Returns with Initialized CURL Handler
     *
     * @param String $mode Mode
     *
     * @return CURL Curl Handler
     */
    private function _getCurlHandler($path, $mode)
    {
        $url = $this->_getJsonPath($path);
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_TIMEOUT, $this->_timeout);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $this->_timeout);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $mode);
        return $ch;
    }
 
    private function _writeData($path, $data, $method = 'PUT')
    {
        $jsonData = json_encode($data);
        $header = array(
            'Content-Type: application/json',
            'Content-Length: ' . strlen($jsonData)
        );
        try {
            $ch = $this->_getCurlHandler($path, $method);
            curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonData);
            $return = curl_exec($ch);
            curl_close($ch);
        } catch (Exception $e) {
            $return = null;
        }
        return $return;
    }
 
}

     

    And now the most importand file that you also have to upload to your hosting directory. Its the file that will respond to Arduino requests.

    <?php
require_once 'firebaseLib.php';
// --- This is your Firebase URL
$url = 'https://xxxxxx.firebaseio.com/';
// --- Use your token from Firebase here
$token = 'xxxxxxxxxxxxxxx';
// --- Here is your parameter from the http GET
$arduino_data = $_GET['arduino_data'];
// --- $arduino_data_post = $_POST['name'];
// --- Set up your Firebase url structure here
$firebasePath = '/';
/// --- Making calls
$fb = new fireBase($url, $token);
$response = $fb->push($firebasePath, $arduino_data);
sleep(2);

    So now if you do a manual request to http://www.yourdomain.com/firbaseTest.php?arduino_data=21.00 the value 21.00 should be stored in your firebase database.

     

    Now the only thing that is left is to make the Arduino send the actually readings. So instead of the dummy “21.00” that we put manually before we will have the real temp readings.  The arduino code is this one:

    #include <SPI.h>
#include <Ethernet.h>
#include <OneWire.h> 
 
int DS18S20_Pin = 2;
OneWire ds(DS18S20_Pin);  // on digital pin 2
 
// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
char serverName[] = "ardufirebase.azurewebsites.net";    // name address of your domain
 
// Set the static IP address to use if the DHCP fails to assign
IPAddress ip(192,168,0,177);
int serverPort = 80;
EthernetClient client;
int totalCount = 0;
char pageAdd[64];
 
char tempString[] = "00.00";
 
// set this to the number of milliseconds delay
// this is 5 seconds
#define delayMillis 5000UL
 
unsigned long thisMillis = 0;
unsigned long lastMillis = 0;
 
void setup() {
  Serial.begin(9600);
 
  // disable SD SPI
  pinMode(4,OUTPUT);
  digitalWrite(4,HIGH);
 
  // Start ethernet
  Serial.println(F("Starting ethernet..."));
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    // try to congifure using IP address instead of DHCP:
    Ethernet.begin(mac, ip);
  }
 
  digitalWrite(10,HIGH);
 
  Serial.println(Ethernet.localIP());
 
  delay(2000);
  Serial.println(F("Ready"));
}
 
void loop()
{  
  thisMillis = millis();
 
  if(thisMillis - lastMillis > delayMillis)
  {
    lastMillis = thisMillis;
 
    float temperature = getTemp();
    Serial.println(ftoa(tempString,temperature,2));
    sprintf(pageAdd,"/firebaseTest.php?arduino_data=%s",ftoa(tempString,temperature,2));
    if(!getPage(serverName,serverPort,pageAdd)) Serial.print(F("Fail "));
    else Serial.print(F("Pass "));
    totalCount++;
    Serial.println(totalCount,DEC);
  }    
}
 
byte getPage(char *ipBuf,int thisPort, char *page)
{
  int inChar;
  char outBuf[128];
 
  Serial.print(F("connecting..."));
 
  if(client.connect(ipBuf,thisPort))
  {
    Serial.println(F("connected"));
 
    sprintf(outBuf,"GET %s HTTP/1.1",page);
    client.println(outBuf);
    sprintf(outBuf,"Host: %s",serverName);
    client.println(outBuf);
    client.println(F("Connection: close\r\n"));
  } 
  else
  {
    Serial.println(F("failed"));
    return 0;
  }
 
  // connectLoop controls the hardware fail timeout
  int connectLoop = 0;
 
  while(client.connected())
  {
    while(client.available())
    {
      inChar = client.read();
      Serial.write(inChar);
      // set connectLoop to zero if a packet arrives
      connectLoop = 0;
    }
 
    connectLoop++;
 
    // if more than 10000 milliseconds since the last packet
    if(connectLoop > 10000)
    {
      // then close the connection from this end.
      Serial.println();
      Serial.println(F("Timeout"));
      client.stop();
    }
    // this is a delay for the connectLoop timing
    delay(1);
  }
 
  Serial.println();
 
  Serial.println(F("disconnecting."));
  // close client end
  client.stop();
 
  return 1;
}
 
float getTemp(){
  //returns the temperature from one DS18S20 in DEG Celsius
 
  byte data[12];
  byte addr[8];
 
  if ( !ds.search(addr)) {
      //no more sensors on chain, reset search
      ds.reset_search();
      return -1000;
  }
 
  if ( OneWire::crc8( addr, 7) != addr[7]) {
      Serial.println("CRC is not valid!");
      return -1000;
  }
 
  if ( addr[0] != 0x10 && addr[0] != 0x28) {
      Serial.print("Device is not recognized");
      return -1000;
  }
 
  ds.reset();
  ds.select(addr);
  ds.write(0x44,1); // start conversion, with parasite power on at the end
 
  byte present = ds.reset();
  ds.select(addr);    
  ds.write(0xBE); // Read Scratchpad
 
  for (int i = 0; i < 9; i++) { // we need 9 bytes
    data[i] = ds.read();
  }
 
  ds.reset_search();
 
  byte MSB = data[1];
  byte LSB = data[0];
 
  float tempRead = ((MSB << 8) | LSB); //using two's compliment
  float TemperatureSum = tempRead / 16;
 
  return TemperatureSum;
 
}
 
char *ftoa(char *a, double f, int precision)
{
  long p[] = {0,10,100,1000,10000,100000,1000000,10000000,100000000};  
  char *ret = a;
  long heiltal = (long)f;
  itoa(heiltal, a, 10);
  while (*a != '\0') a++;
  *a++ = '.';
  long desimal = abs((long)((f - heiltal) * p[precision]));
  itoa(desimal, a, 10);
  return ret;
}

    Here we used parts of the web client example code from arduino.cc. So in a few words what we are doing is we are making a request and we pass the current temperature reading. It is set to do the request every 5 seconds. The most difficult part for was to convert the float value in string.

     

    Here is a video:

    Here we are creating a simple html file and with some javascript and a jquery chart plugin and just showing the current temperature from the  room and a graph of it.

    The index html:

    <html>
	<head>
		<script type='text/javascript' src='https://cdn.firebase.com/js/client/1.0.6/firebase.js'></script>		
		<script language="javascript" type="text/javascript" src="http://code.jquery.com/jquery-2.1.0.min.js"></script>
		<script type="text/javascript" src="http://people.iola.dk/olau/flot/jquery.flot.js"></script>
		<script src="controller.js"></script>
		<link rel="stylesheet" type="text/css" href="bootstrap.min.css" />
	</head>
	<body>
		<div style="width:800px; margin:0 auto;">
			<div><h1 id='tempMsg' style='display:none;width:550px; margin:0 auto;margin-top: 50px;'>Current temp: <span id="currTemp"></span>&deg;C</h1></div>
			<div id="chart1" style="width:600px;height:300px;"></div> 
		</div>
	</body>
	<footer></footer>
</html>

    And the javascript file (controller.js)

    $(document).ready(function() {
	var tempsArray = [];
	var tArray = [];
	var sessionArray = [];
	var currTemp = '';
 
	var dataRef = new Firebase('https://arduino-test.firebaseio.com');
	dataRef.on('value', function(snapshot) {
		var t = snapshot.val();
		var count = 0;
 
		for (var key in t) {
		  if (t.hasOwnProperty(key)) {		    
		    var dt = [];	    
		    dt[0] = count;
		    dt[1] = parseFloat(t[key]);
		    tempsArray = [];
		    tempsArray.push(dt);
		    tArray = [];
		    tArray.push(dt[1]);
		    count++;
		  }
		}
		sessionArray.push(tempsArray[0])
		//console.log(tempsArray)
		$.plot($("#chart1"), [ sessionArray ]);
		currTemp = tempsArray[0][1].toString();
		$('#tempMsg').show();
		$("#currTemp").text(currTemp);
	});			
});

     

    Sample Graph

     

    Source URL: http://www.devacron.com/arduino-firebase/ 

    Tags: 201802, W5100, Ethernet, Arduino, database, ds1820, Firebase

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    POSTED BY
    Albin