Mega R3 ATmega2560 and WiFi ESP8266 with 32MB RAM are fully integrated on a single board. All of the modules can be used together or individually. And everyone's pinout headers are unique. The practical option for developing new ideas that require Uno and WiFi. You can update ATmega2560 and ESP8266 sketches and firmware over USB. The USB-to-serial converter ch340G is on board for this. It's really easy to use this board.

This board also has a selector switch that allows the ESP to interleave the TX0 and TX3 connections, keeping in mind that the ATmega has four serial ports. The DIP Switch is a second selection switch; the ATmega has 32MB of memory, not including the ESP memory. Because the standard Mega Arduino only has 256kb of RAM, this is fantastic. The RobotDyn requires 7 to 12 volts of power, while the ESP8266 is already powered and includes a voltage reducer. So feeding the Arduino is already feeding the ESP, which is already at 3v3, and the microcontroller itself is already at 3v3. The processors are the same, 16MHz, and one great advantage of these models is the high amount of IOs.

Table DIP- switch:

 
Special solution:

USB <->ATmega328<-> ESP8266

Simple Code for the MEGA WiFi R3 ATmega2560+ESP8266:

Put the switch numbers 1,2,3,4 to ON, and 5,6,7,8 to OFF. This way, the USB will be connected to ATmega2560 (the Arduino Mega) and not the ESP8266. Near the switch, there is another switch, to select where the ESP8266 should be “plugged”. Just keep it at Serial3, like most of the tutorials around the net.

Now upload the Blink code.

/*
 Blink
 Turns an LED on for one second, then off for one second, repeatedly.
 Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
 it is attached to digital pin 13, on the board on pin 6. LED_BUILTIN is set to
 the correct LED pin independent of which board is used.
 If you want to know what pin the on-board LED is connected to on your Arduino
 model, check the Technical Specs of your board at:

*/
// the setup function runs once when you press reset or power the board
void setup() {
 // initialize digital pin LED_BUILTIN as an output.
 pinMode(LED_BUILTIN, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
 digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
 delay(1000); // wait for a second
 digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
 delay(1000); // wait for a second
}