Posting DHT11 Values to ThingSpeak Using Nodemcu (Tutorial-5)

Nodemcu is great WiFi chip and we started our journey with some basic applications, which are as follow:

Getting Started with Nodemcu in Arduino IDE
Getting Temperature and Humidity Values on Phone
Controlling Devices Over WiFi using Phone
Controlling Devices Over WiFi Using Phone without WiFi Router

The common thing in all these posts is that the Nodemcu is present in the local network and that’s why you will get data and can control devices, within your network boundaries. 
For example: You can control devices only from your home network, and not from outside world.
So now we will go beyond the boundaries of our local network and access the Nodemcu over the Internet, and in these series of post, firstly I would like to see the temperature and humidity values of my home measured by Nodemcu using DHT11 sensor, over Internet from any other location or on any other network, and for Completing this task, we will use ThingSpeak.

Block Diagram

What is ThingSpeak?
ThingSpeak is an IoT platform for data collection and analytics that serves as a bridge connecting edge node devices such as temperature, humidity, pressure etc. sensors to collect data and data exploratory analysis software to analyze data.
ThingSpeak serves as the data collector which collects data from edge node devices (Nodemcu/ESP8266 is this case) and also enables the data to be pulled into a software environment for historical analysis of data.
The primary element of ThingSpeak activity is the channel, which contains data fields, location fields, and a status field. After you create a ThingSpeak channel, you can write data to the channel, process and view the data with MATLAB code, and react to the data with tweets and other alerts.
The typical ThingSpeak workflow lets you:

• Create a Channel and collect data
• Analyze and Visualize the data
• Act on the data using any of several Apps

So in the post, we will measure the temperature and humidity values using DHT11 sensor with the help of Nodemcu module and then send these values to ThingSpeak channel, and by doing this you can see the temperature and humidity values of your home from any corner of the world using ThingSpeak.

Follow the following steps to configure:

• Sign In into ThingSpeak account, by using ThingSpeak account or using MathWorks account. 
• Click on My Channels.
• On the channel page, click on New Channel.

Click on New Channel

• As we are using DHT11 sensor to measure the temperature and humidity values, we will name our channel as Measurements (You can choose any other desired name).
• Provide some description though it’s not mandatory.
• Update Field-1 with Temperature and Field-2 with Humidity (Number of fields can be updated as per your project requirement).
• You can select some other settings as well and after that you can save your channel.
• After saving the channel you will see 5 tabs, Private View, Public View, Channel Setting, API Keys, Data Import/Export.

5 Tabs of the Channel.

• You can modify the Title, X-Axis, Y-Axis, scales of Field-1 and Field-2 for Private View and Public View of the Channel.

Change Setting

• Now time to update the Nodemcu code written in Arduino IDE, copy the Channel ID and Write API Key from API Keys tab and update it in Arduino IDE program.

Update Channel ID and Write API Key in Nodemcu Firmware

• Build your project and flash the Nodemcu with the updated code, and after that you will see the temperature and humidity graphs on the ThingSpeak channel, as shown in the below images.

ThingSpeak Channel After Few Minutes of running the Firmware.

ThingSpeak Channel After 8 Hours

You can download the ThingSpeak library for Arduino by clicking here.

The code written in Arduino IDE for Nodemcu is as follow:

#include <DHT.h>  
#include <ESP8266WiFi.h>  
#include <WiFiClient.h>  
#include <ThingSpeak.h>  
#define DHTPIN D5  
#define DHTTYPE DHT11  
DHT dht(DHTPIN, DHTTYPE);  
const char* ssid = "WiFiName";  
const char* password = "Password";  
WiFiClient client;  
unsigned long myChannelNumber = 174314;  
const char * myWriteAPIKey = "JQPT38EM56K0MJM1";  
uint8_t temperature, humidity;  
void setup()  
{  
  Serial.begin(115200);  
  dht.begin();  
  delay(10);  
  // Connect to WiFi network  
  Serial.println();  
  Serial.println();  
  Serial.print("Connecting to ");  
  Serial.println(ssid);  
  WiFi.begin(ssid, password);  
  while (WiFi.status() != WL_CONNECTED)  
  {  
   delay(500);  
   Serial.print(".");  
  }  
  Serial.println("");  
  Serial.println("WiFi connected");  
  // Print the IP address  
  Serial.println(WiFi.localIP());  
  ThingSpeak.begin(client);  
}  
void loop()   
{  
  static boolean data_state = false;  
  temperature = dht.readTemperature();  
  humidity = dht.readHumidity();  
  Serial.print("Temperature Value is :");  
  Serial.print(temperature);  
  Serial.println("C");  
  Serial.print("Humidity Value is :");  
  Serial.print(humidity);  
  Serial.println("%");  
  // Write to ThingSpeak. There are up to 8 fields in a channel, allowing you to store up to 8 different  
  // pieces of information in a channel. Here, we write to field 1.  
  if( data_state )  
  {  
   ThingSpeak.writeField(myChannelNumber, 1, temperature, myWriteAPIKey);  
   data_state = false;  
  }  
  else  
  {  
   ThingSpeak.writeField(myChannelNumber, 2, humidity, myWriteAPIKey);  
   data_state = true;  
  }  
  delay(30000); // ThingSpeak will only accept updates every 15 seconds.  
} 

You can also download the ThingSpeak mobile application ThingView from Google Play Store and directly view the channel graphs in ThingView Application.

Following are the steps to setup the ThingView Application on your Android Phone.

Open ThingView Application, and click on Add Button.

After Clicking on Add button, Enter the Channel ID, then Search and select the Channel.

Your Channel is Added, you can view the Graphs directly on your Smart Phone.

Following are the screenshots of the graphs taken from the ThingView mobile application.

All steps given above are documented in this video, so have a look at this video.

Also Read the following posts:

Getting Started with MQTT using Mosquitto

Getting Started with MQTT Using Python

DHT11 Interfacing with PIC and Displaying Data on OLED Display