ESP8266 (Arduino IDE) and Thingspeak with Webserver for debugging | ThingSpeak Projects | Forum

Sends data to Thingspeak and also shows sent data and response on a web page hosted on
the ESP8266 for local information to aid in debugging.

    Version: 1.0 (07 Jul 16)
    Hardware: ESP8266 module (specifically the Sparkfun ESP8266 Thing)
    IDE: Arduino 1.6.9
    
    Author: Ewan Regazzo                    */

#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <WiFiClient.h>

// WiFi Definitions
#define SSID "myssid" // WiFi SSID
#define PSK "mypassword" // WiFi password

// Thingspeak definitions
#define SERVER "184.106.153.149" // Thingspeak server address (don't use 'api.thingspeak.com' - it doesn't work)
#define PORT 80 // Thingspeak port
#define API "myapiwritekey" // Thingspeak 'Write' key for this channel

/* NOTE 1 - The instance of ESP8266WebServer called 'server' uses port 81.
   Port 81 must be used as Thingspeak uses port 80, so the web server by typing
   XXX.XXX.XXX.XXX:81 into your browser window where XXX.XXX.XXX.XXX is the IP
   address of the ESP8266 - ie, '192.168.0.5:81'
   The '#include <ESP8266WebServer.h>' statement at the top of this code is
   essential in allowing the 'server' instance to be created.*/

ESP8266WebServer server(81); // Create instance of ESP8266WebServer called 'server' using port 81 (see note 1 above)

WiFiClient client; // Create an instance of WiFiClient called 'client'

// Global variables (usable by all functions)
int x = 0; // Simple counter to show that something changes
String message; // The information needed to update Thingspeak is kept in a string called 'message'
String response; // Holds the response information from Thingspeak after data has been sent

// The 'setup' function is called at startup only and sets up the ESP8266
void setup()
{
  WiFi.begin(SSID, PSK); // Begin the WiFi connection using SSID and PSK definitions

  // Pause for 0.5 seconds while WiFi is NOT connected
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
  }
  
  // we've gotten to here so WiFi must now be connected

  // Set up the web server
  server.on("/", handleRoot); // If a client accesses the root page ('/') then process the 'handleRoot' function
  server.begin(); // Start the server
}

// The main function that does everything.
void loop()
{
  createData(); // Make the data message
  server.handleClient(); // Take care of any client that accesses the web server
  sendData(); // send data to Thingspeak
  delay(5000); // Have a break
}

// This function takes care of a client accessing the root web server page
void handleRoot()
{
  server.send(200, "text/plain", (message + "
" + response)); // send a message to the web server
}

// This function sets the ESP8266 as a client to an external server (Thingspeak), sends data,
// and receives a response
void sendData()
{
  if (client.connect(SERVER, PORT)) // If a successful connection occurs, then...
  {
    client.println(message); // ... send the information
  }

  if (client.connected()) // If we have connected...
  {
    response = client.read(); // ... read the response from the server
    
    if (response == "48") // string value of "48" equals char '0' - which means data received ok
    {
      x ++; // increment x by 1 (just to show that something happened)
    }
  }

  client.stop(); // We don't want the client to maintain a constant connection
}

// This function creates a simple GET message string to update Thingspeak
void createData()
{
  message = "GET /update?api_key=";
  message += API;
  message += "&field1=";
  message += x;
}