esp8266 to arduino mega connection

hello i would like to know how we want to connect esp8266 to arduino mega(circuit diagram)

Let me Google that for you ...

Depending on your type, there is only 4 wires. 2 for power and 2 for coms. Esp rx and tx to arduino tx and rx. Rx from esp to arduino tx. Tx from esp to arduino rx

Just keep in mind that the Arduino operates at 5V, and the ESP at 3.3V, so connecting them without a level shifter will kill the ESP.

Power delivery can be tricky as well. You can read more in my Beginner's guide to the ESP8266.

Pieter

Welsyntoffie: Depending on your type, there is only 4 wires. 2 for power and 2 for coms. Esp rx and tx to arduino tx and rx. Rx from esp to arduino tx. Tx from esp to arduino rx

I would say there is more to it than just that.

You need to understand HOW to put in AT/COMMAND mode//programming mode..etc..etc..

PieterP: ....You can read more in my Beginner's guide to the ESP8266.

Pieter

Very nice guide, @Pieter.

DaveEvans: Very nice guide, @Pieter.

Agree. I'm only at chapter 10 of the 20 and have learned vast amount of crucial basic info. A well thought out consolidated piece without wading too far into weeds. This pairs well with info received from others. It should be prereq reading material for wifi newbies like myself.

Thanks Pieter.

I just wanted to do a follow up with some quick code of the info I learned from Pieter that most of us wifi newbies are interested in:
1.) pass textbox info from webpage info to ESP8266
2.) pass button press info to ESP8266
3.) list simple html code into a recognizable pattern

#include <WiFiClient.h>
#include <ESP8266WiFi.h>
#include <ESP8266mDNS.h>

#include <ESP8266WebServer.h>

ESP8266WebServer ESP8266server(80);
const char* WIFI_SSID = "yourSSID";
const char* WIFI_PASS = "yourPASS";
const char* html = 
                   "<form action=\"/login\" method=\"POST\">"
                   "<input type=\"text\" name=\"username\" placeholder=\"Username\">
"
                   "<input type=\"password\" name=\"password\" placeholder=\"Password\">
"
                   "<input type=\"text\" name=\"ipAddr\" placeholder=\"IP Adress\">
"
                   "<input type=\"text\" name=\"submask\" placeholder=\"Submask\">
"
                   "<input type=\"text\" name=\"gateway\" placeholder=\"Gateway\">
"
                   "<input type=\"submit\" value=\"Login\"></form>"
                   "<form action=\"/LEDON\" method=\"POST\"><input type=\"submit\" value=\"LED ON\"></form>"
                   "<form action=\"/LEDOFF\" method=\"POST\"><input type=\"submit\" value=\"LED OFF\"></form>"
                   "<p>Try 'John Doe' and 'password123' ...</p>";

#define SERIAL_BAUDRATE                 115200

void wifiSetup() {

    // Set WIFI module to STA mode
    WiFi.mode(WIFI_STA);

        IPAddress ip(10,6,5,25);  //Node static IP
        IPAddress gateway(10,6,5,75);
        IPAddress subnet(255,255,255,0); 

        WiFi.begin(WIFI_SSID, WIFI_PASS);
        WiFi.config(ip,gateway, subnet);

        while (WiFi.status() != WL_CONNECTED) {delay(100);}
        
        if (MDNS.begin("esp8266")) {              // Start the mDNS responder for esp8266.local
            Serial.println("mDNS responder started");
        } else {
            Serial.println("Error setting up MDNS responder!");
        }
        
        ESP8266server.on("/", HTTP_GET, handleRoot);     // Call the 'handleRoot' function when a client requests URI "/"
        ESP8266server.on("/LEDON", HTTP_POST, handleLEDON);
        ESP8266server.on("/LEDOFF", HTTP_POST, handleLEDOFF);
        ESP8266server.on("/login", HTTP_POST, handleLogin);
        ESP8266server.onNotFound(handleNotFound);        // When a client requests an unknown URI (i.e. something other than "/"), call function "handleNotFound"

        ESP8266server.begin();                           // Actually start the server
  
}

void setup() {

    Serial.begin(SERIAL_BAUDRATE);
    Serial.println();

    wifiSetup();
}

void handleRoot() {                         // When URI / is requested, send a web page with a button to toggle the LED
      ESP8266server.send(200, "text/html", html);
}

void handleLEDON() {                          // If a POST request is made to URI /LED
  //digitalWrite(led,!digitalRead(led));      // Change the state of the LED
  ESP8266server.sendHeader("Location","/");   // Add a header to respond with a new location for the browser to go to the home page again
  ESP8266server.send(303);                    // Send it back to the browser with an HTTP status 303 (See Other) to redirect
  Serial.println("LED ON");
}
void handleLEDOFF() {                          // If a POST request is made to URI /LED
  //digitalWrite(led,!digitalRead(led));      // Change the state of the LED
  ESP8266server.sendHeader("Location","/");   // Add a header to respond with a new location for the browser to go to the home page again
  ESP8266server.send(303);                    // Send it back to the browser with an HTTP status 303 (See Other) to redirect
  Serial.println("LED OFF");
}
void handleLogin() {                         // If a POST request is made to URI /login
      
      if( ! ESP8266server.hasArg("username") || ! ESP8266server.hasArg("password") 
      || ESP8266server.arg("username") == NULL || ESP8266server.arg("password") == NULL) { // If the POST request doesn't have username and password data
              ESP8266server.send(400, "text/plain", "400: Invalid Request");         // The request is invalid, so send HTTP status 400
              return;
      }

      String response = "<h1>Welcome, " + ESP8266server.arg("username") + "!</h1>"
                        "<p>Login successful</p>"
                        "<p>New IP Address= " + ESP8266server.arg("ipAddr") + "</p>"
                        "<p>New Submask= " + ESP8266server.arg("submask") + "</p>"
                        "<p>New Gateway= " + ESP8266server.arg("gateway") + "</p>";
                        
      if(ESP8266server.arg("username") == "John Doe" && ESP8266server.arg("password") == "password123") { // If both the username and the password are correct
              ESP8266server.send(200, "text/html",response);
      } else {                                                                              // Username and password don't match
              ESP8266server.send(401, "text/plain", "401: Unauthorized");
      }
}
void handleNotFound(){
  ESP8266server.send(404, "text/plain", "404: Not found"); // Send HTTP status 404 (Not Found) when there's no handler for the URI in the request
}

void loop() {
    ESP8266server.handleClient();                    // Listen for HTTP requests from clients
}

I highly recommend reading Pieter’s piece from start to finish. Now to dress it up by continuing to learn html from codecademy.com (as recommended by xl97) and www.w3schools.com (as recommended by Robin2).

Many thanks!!
JM