Fig. 6: Table listing pin configuration of FTDI USB to Serial Converter

The Ground terminal of the FTDI converter is connected to the common ground while the TXD and RXD terminals are connected to the RX and TX pins of the ESP8266 module. The FTDI adapter is used to program the ESP module using Arduino IDE. 

In order to make sure that Apache is running, open a web browser and type local host in the address bar. The following control panel must appear on accessing the localhost. 

As seen, the webpage simply contains two buttons – one to switch on the LED and other to switch off the LED. There is also a label at the bottom of the webpage which shows the current status of the LED. 

//Program to

#include <ESP8266WiFi.h>

#include <ArduinoJson.h>


const char* ssid     = "***********";  //Your wifi name

const char* password = "************"; //your password


const char* host     = "192.168.110.19"; // Your domain  

String path          = "/webserver_led/light.json";  

const int pin        = 2;


void setup() {  

  pinMode(pin, OUTPUT); 

  pinMode(pin, HIGH);

  Serial.begin(115200);


  delay(10);

  Serial.print("Connecting to ");

  Serial.println(ssid);


  WiFi.begin(ssid, password);

  int wifi_ctr = 0;

  while (WiFi.status() != WL_CONNECTED) {

    delay(500);

    Serial.print(".");

  }


  Serial.println("WiFi connected");  

  Serial.println("IP address: " + WiFi.localIP());

}


void loop() {  

  Serial.print("connecting to ");

  Serial.println(host);

  WiFiClient client;

  const int httpPort = 80;

  if (!client.connect(host, httpPort)) {

    Serial.println("connection failed");

    return;

  }


  client.print(String("GET ") + path + " HTTP/1.1rn" +

               "Host: " + host + "rn" + 

               "Connection: keep-alivernrn");


  delay(500); // wait for server to respond


  // read response

  String section="header";

  while(client.available()){

    String line = client.readStringUntil('r');

    // Serial.print(line);

    // we’ll parse the HTML body here

    if (section=="header") { // headers..

      Serial.print(".");

      if (line=="n") { // skips the empty space at the beginning 

        section="json";

      }

    }

    else if (section=="json") {  // print the good stuff

      section="ignore";

      String result = line.substring(1);


      // Parse JSON

      int size = result.length() + 1;

      char json[size];

      result.toCharArray(json, size);

      StaticJsonBuffer<400> jsonBuffer;

      JsonObject& json_parsed = jsonBuffer.parseObject(json);

      if (!json_parsed.success())

      {

        Serial.println("parseObject() failed");

        return;

      }


      // Make the decision to turn off or on the LED

      if (strcmp(json_parsed["light"], "on") == 0) {

        digitalWrite(pin, HIGH); 

        Serial.println("LED ON");

      }

      else {

        digitalWrite(pin, LOW);

        Serial.println("led off");

      }

    }

  }

  Serial.print("closing connection. ");