Arduino Support for ESP8266 with simple test code

Nodemcu is not just a WiFi module, it also has a decent micro-controller in built. Nodemcu comes with 32-bit Tensilica Processor, Power-Saving Architecture, Compactness, High Durability. In this small tutorial, I will show you how easy it is to add Arduino Support.

​Download Arduino IDE from https://www.arduino.cc/en/Main/Software

Install the ESP8266 Board Package

• Select the Preferences under File.
• Enter http://arduino.esp8266.com/stable/package_esp8266com_index.json into Additional Boards Manager URL’s field under preferences as shown below.

• Next, Select the Board manager under Tools.

• Next, use the Board manager to install the ESP8266 package.

• Now last step Restart the Arduino IDE and Select the specific Board. Go to Tools =>Board and select “Generic ESP8266 Module” Now you can use ESP8266 with Arduino IDE.

Test Example of DHT11 Temperature & Humidity sensor on NodeMCU using Arduino IDE

The DHT11 is chosen because it is lab calibrated, accurate and stable and its signal output is digital. Most important of all, it is relatively inexpensive for the given performance. Below is the pinout of the sensor.

Installing Libraries

• Click here to download the DHT sensor library.
• Unzip the .zip folder and you should get DHT-sensor-library-master folder
• Rename your folder from DHT-sensor-library-master to DHT
• Move the DHT folder to your Arduino IDE installation libraries folder
• You also need to install the Adafruit Unified Sensor Driver Library.
• Unzip the .zip folder and you should get Adafruit_sensor-master folder
• Rename your folder from Adafruit_sensor-master to Adafruit_sensor
• Move the DHT_sensor folder to your Arduino IDE installation libraries folder
• Finally, re-open your Arduino IDE

Copy the sketch below to your Arduino IDE. Replace the SSID and password with your own credentials.

// Including the ESP8266 WiFi library
#include <ESP8266WiFi.h>
#include "DHT.h"

// Uncomment one of the lines below for whatever DHT sensor type you're using!
#define DHTTYPE DHT11   // DHT 11

// Replace with your network details
const char* ssid = "YOUR_NETWORK_NAME";
const char* password = "YOUR_NETWORK_PASSWORD";

// Web Server on port 80
WiFiServer server(80);

// DHT Sensor
const int DHTPin = 5;
// Initialize DHT sensor.
DHT dht(DHTPin, DHTTYPE);

// Temporary variables
static char celsiusTemp[7];
static char fahrenheitTemp[7];
static char humidityTemp[7];

// only runs once on boot
void setup() {
  // Initializing serial port for debugging purposes
  Serial.begin(115200);
  delay(10);

  dht.begin();
  
  // Connecting to WiFi network
  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");
  
  // Starting the web server
  server.begin();
  Serial.println("Web server running. Waiting for the ESP IP...");
  delay(10000);
  
  // Printing the ESP IP address
  Serial.println(WiFi.localIP());
}

// runs over and over again
void loop() {
  // Listenning for new clients
  WiFiClient client = server.available();
  
  if (client) {
    Serial.println("New client");
    // bolean to locate when the http request ends
    boolean blank_line = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        
        if (c == '\n' && blank_line) {
            // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
            float h = dht.readHumidity();
            // Read temperature as Celsius (the default)
            float t = dht.readTemperature();
            // Read temperature as Fahrenheit (isFahrenheit = true)
            float 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!");
              strcpy(celsiusTemp,"Failed");
              strcpy(fahrenheitTemp, "Failed");
              strcpy(humidityTemp, "Failed");         
            }
            else{
              // Computes temperature values in Celsius + Fahrenheit and Humidity
              float hic = dht.computeHeatIndex(t, h, false);       
              dtostrf(hic, 6, 2, celsiusTemp);             
              float hif = dht.computeHeatIndex(f, h);
              dtostrf(hif, 6, 2, fahrenheitTemp);         
              dtostrf(h, 6, 2, humidityTemp);
              // You can delete the following Serial.print's, it's just for debugging purposes
              Serial.print("Humidity: ");
              Serial.print(h);
              Serial.print(" %\t Temperature: ");
              Serial.print(t);
              Serial.print(" *C ");
              Serial.print(f);
              Serial.print(" *F\t Heat index: ");
              Serial.print(hic);
              Serial.print(" *C ");
              Serial.print(hif);
              Serial.print(" *F");
              Serial.print("Humidity: ");
              Serial.print(h);
              Serial.print(" %\t Temperature: ");
              Serial.print(t);
              Serial.print(" *C ");
              Serial.print(f);
              Serial.print(" *F\t Heat index: ");
              Serial.print(hic);
              Serial.print(" *C ");
              Serial.print(hif);
              Serial.println(" *F");
            }
            client.println("HTTP/1.1 200 OK");
            client.println("Content-Type: text/html");
            client.println("Connection: close");
            client.println();
            // your actual web page that displays temperature and humidity
            client.println("<!DOCTYPE HTML>");
            client.println("<html>");
            client.println("<head></head><body><h1>ESP8266 - Temperature and Humidity</h1><h3>Temperature in Celsius: ");
            client.println(celsiusTemp);
            client.println("*C</h3><h3>Temperature in Fahrenheit: ");
            client.println(fahrenheitTemp);
            client.println("*F</h3><h3>Humidity: ");
            client.println(humidityTemp);
            client.println("%</h3><h3>");
            client.println("</body></html>");     
            break;
        }
        if (c == '\n') {
          // when starts reading a new line
          blank_line = true;
        }
        else if (c != '\r') {
          // when finds a character on the current line
          blank_line = false;
        }
      }
    }  
    // closing the client connection
    delay(1);
    client.stop();
    Serial.println("Client disconnected.");
  }
}   

Open the Arduino IDE serial monitor at a baud rate of 115200. After a few seconds your IP address should appear. Open any browser from a device that is connected to the same router that your ESP is. Then type the IP address and click Enter!, Now you can see temp and humd in browser.

Pin Diagram

• DHT 11 vcc => 5V pin Nodemcu
• DHT 11 GND => GND pin Nodemcu
• DHT 11 Data => D1 pin Nodemcu