https://robotdyn.com/mega-wifi-r3-atmega2560-esp8266-flash-32mb-usb-ttl-ch340g-micro-usb.html
I can't work with the WiFi feature because in each mode, the board does not response to AT commands.
when I set dip switches 5 and 6 to ON and the other switch to RXD3 TXD3, then directly send AT command from serial terminal of Arduino IDE but don't receive response from board (I set terminal to send both NL and CR)
also when set dip switches 1,2,3,4 to ON and the other switch to RXD3 TXD3, can't send AT command by Arduino to ESP and take response by a lot of codes like this:
void setup()
{
Serial.begin(9600); // communication with the host computer
Serial3.begin(115200);
Serial.println("");
Serial.println("Remember to to set Both NL & CR in the serial monitor.");
Serial.println("Ready");
Serial.println("");
}
void loop()
{
// listen for communication from the ESP8266 and then write it to the serial monitor
if ( Serial3.available() ) { Serial.write( Serial3.read() ); }
// listen for user input and send it to the ESP8266
if ( Serial.available() ) { Serial3.write( Serial.read() ); }
}