Pankaj Rai
Published © MIT

NodeMCU Connecting LM35-Based Temperature Monitoring System

This is a temperature monitoring system using LM35 interfacing with NodeMCU.

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NodeMCU Connecting LM35-Based Temperature Monitoring System

Things used in this project

Hardware components

NodeMCU ESP8266 Breakout Board
NodeMCU ESP8266 Breakout Board
×1
LM35 sensor
×1

Software apps and online services

Arduino IDE
Arduino IDE
ThingIO.AI

Story

Read more

Schematics

circuit diagram for connection of LM35 and NodeMCU

output of sensor will be connecting to analog pin (A0) of NodeMCU. and vcc and gnd as usual.

Code

LM35 intefaced with NodeMCU for temperature monitoring system

Arduino
#include <SoftwareSerial.h>
SoftwareSerial mySerial(12, 13); // RX, TX

#include <ESP8266WiFi.h>          //https://github.com/esp8266/Arduino
#include <DNSServer.h>
#include <ESP8266WebServer.h>
#include "WiFiManager.h"          //https://github.com/tzapu/WiFiManager

int count=0,i,m,j,k;
int t,t1,t2,t3;
int outputpin= A0;//ds18b20 


//////////////////////////////////////// ALL DECLARATIONS for CLOUD //////////////////////////////
const char* host = "api.thingsio.ai";                                 // OR host = devapi2.thethingscloud.com
const char* post_url = "/devices/deviceData";       // OR /api/v2/thingscloud2/_table/data_ac
const char* time_server = "baas.thethingscloud.com";             //this is to convert timestamp
const int httpPort = 80;

char timestamp[10];

WiFiClient client;
  


/////////////////////////////////////////////////////////////////////////////////////////////////////////
void configModeCallback (WiFiManager *myWiFiManager) 
{
  Serial.println("Entered config mode");             //*-*-*-*-*-*-*-*-*-*-*-*-*-*if control enters this function then net is not connected
  Serial.println(WiFi.softAPIP());                  // "WiFi.softAPIP() is for AP" , "WiFi.localIP() is for STA",
                                                                
  Serial.println(myWiFiManager->getConfigPortalSSID());             //if you used auto generated SSID, print it
}
/////////////////////////////////////// TIMESTAMP CALCULATION function///////////////////////////////////////
int GiveMeTimestamp()
{
  unsigned long timeout = millis();

  while (client.available() == 0)
  {
    if (millis() - timeout > 50000)
    {
      client.stop();
      return 0;
    }
  }

while (client.available())
      {
        String line = client.readStringUntil('\r');                    //indexOf() is a funtion to search for smthng , it returns -1 if not found
        int pos = line.indexOf("\"timestamp\"");                       //search for "\"timestamp\"" from beginning of response got and copy all data after that , it'll be your timestamp
        if (pos >= 0)                                                     
        {
          int j = 0;
          for(j=0;j<10;j++)
          {
            timestamp[j] = line[pos + 12 + j];
          }
        }
      }
}  
////////////////////////////////////////////////////////////////////////////////////////////////////////

void setup() 
{
  Serial.begin(115200);     //(19200,SERIAL_8E1) - data size = 8 bits , parity = Even , stop bit =  1bit
mySerial.begin(115200);
  WiFiManager wifiManager;
 
  wifiManager.setAPCallback(configModeCallback);
                                                                                                    
  if(!wifiManager.autoConnect("iPankaj","00010001"))                   //wifiManager.autoConnect("AP-NAME", "AP-PASSWORD"); (OR) wifiManager.autoConnect("AP-NAME"); only ID no password (OR) wifiManager.autoConnect(); this will generate a ID by itself
  {
    Serial.println("failed to connect and hit timeout");     //control comes here after long time of creating Access point "NodeMCU" by NodeMCU and still it has not connected
                                                               //reset and try again, or maybe put it to deep sleep
    ESP.reset();
    delay(1000);
  } 

  //if you come here you have connected to the WiFi
  Serial.println("connected...yeey :");
 
}

void loop() 
{
  int analogValue = analogRead(outputpin);
{
 
  
/////////////////////////////////////// SEND THE QUERY AND RECEIVE THE RESPONSE///////////////////////  



        t1=(analogValue/1024.0) *3300;    // multiplied with 3300 because I am                                              using 3.3 volts for vcc of lm35
        Serial.print("temp: ");
        Serial.println(t1);

        t2=(t1/10);
        Serial.print("celc: ");
        Serial.println(t2);

        t3=((t2 * 9)/5 + 32);
        Serial.print("fhrn: ");
        Serial.println(t3);        //break;

          

  Serial.print("connecting to ");
  Serial.println(host);                          //defined upside :- host = devapi2.thethingscloud.com or 139.59.26.117

///////////////////////////////////// TIMESTAMP CODE SNIPPET /////////////////////////
Serial.println("inside get timestamp\n");
  if (!client.connect(time_server, httpPort)) 
  {
    return;                                                        //*-*-*-*-*-*-*-*-*-*
  }

  client.println("GET /api/timestamp HTTP/1.1");                            //Whats this part doing, i didnt get
  client.println("Host: baas.thethingscloud.com");
  client.println("Cache-Control: no-cache");
  client.println("Postman-Token: ea3c18c6-09ba-d049-ccf3-369a22a284b8");
  client.println();

GiveMeTimestamp();                        //it'll call the function which will get the timestamp response from the server
Serial.println("timestamp receieved");
Serial.println(timestamp);
///////////////////////////////////////////////////////////////////////////////

// Use WiFiClient class to create TCP connections
  if (!client.connect(host, httpPort))            //host = devapi2.thethingscloud.com , port = 80
  {
    Serial.println("connection failed");                  // *-*-*-*-*-*--*-*-*-*-*-*-*-*-*-*-*-*-
    return;
  }
  
  client.print("Content-Length: ");
  client.println(); 

  unsigned long timeout = millis();
  while (client.available() == 0) 
  {
    if (millis() - timeout > 50000) 
    {
      Serial.println(">>> Client Timeout !");
      client.stop();
      return;
    }
  }
  
  Serial.println("***********************************************");
  Serial.println();
  Serial.println("closing connection");

  Serial.println("inside ThingsCloudPost");

 
  String PostValue = "{\"device_id\": 6112051, \"slave_id\": 2";
         PostValue = PostValue + ",\"dts\":" +timestamp;
   PostValue = PostValue +",\"data\":{\"celc\":" + t2 +",\"fahr\":" + t3 +"}"+"}";
  
  
  Serial.println(PostValue);

//////////////////////////////// try to connect to server again and POST the data on the cloud //////////////////////////
  if (!client.connect(host, httpPort)) 
  {
    return;
  }

  client.print("POST ");
  client.print(post_url);               /// POST api/device-datas         HTTP/1.1     Host: baas.thethingscloud.com      Content-Type: application/json        Cache-Control: no-cache
  client.println(" HTTP/1.1");           //Authorization:          Content-Length: 
  client.print("Host: ");
  client.println(host);
  client.println("Content-Type: application/json");
  client.println("Cache-Control: no-cache");
  client.print("Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.IjViZTU3MzdmNDAyYjlkNGI5MDdiYmM0NCI.R6MXL2hE5WQDoDGETLfZkLLHioPxzAh4Gjd9PWvUhg0");
  client.println();
  client.print("Content-Length: ");
  client.println(PostValue.length());
  client.println();
  client.println(PostValue);
  
//////////////////////////////////POSTING the data on to the cloud is done and now get the response form cloud server//////////////////
  while (client.available() == 0) 
  {
    if (millis() - timeout > 50000) 
    {
      Serial.println(">>> Client Timeout !");
      client.stop();
      return;
    }
  }
  
  Serial.println("Response From Server");
  while(client.available())
  { 
    String line2 = client.readStringUntil('\r');   
    Serial.print(line2);
    
  }
    
Serial.println("//////////////////////    THE END     /////////////////////");
delay(3000);
}
}

Credits

Pankaj Rai

Pankaj Rai

10 projects • 33 followers
B.Tech (Electronics and communication Engineering), Enthusiastic about IOT , Robotics and Automation technologies. (Mb. - 9872647369)

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