Connect ESP8266 (WiFi module) to Arduino Due

Just to prove the connection between Arduino Due (TX3/RX3) and ESP8266 WiFi module, electrically and logically. Because both Arduino Due and ESP8266 work on 3.3V, so no voltage converter is needed.

ESP8266 GND - Due GND

ESP8266 VCC - Due 3.3V

ESP8266 TX - Due RX3

ESP8266 RX - Due TX3

ESP8266 CH_PD - Due pin 53 (always HIGH)

The test program on Arduino Due simple redirect the received data from RX to TX3, and from RX3 to TX. Such that we can use Serial Monitor of Arduino IDE (TX/RX) to send command to ESP8266 (TX3/RX3). It act as a USB-Serial cable functionally. Pin 53 always High, such that the ESP8266 always NOT Power Down.

int LED = 13;
boolean LEDst = false;

//always high
int CH_PD_8266 = 53;

void setup() {
  Serial.begin(9600);
  Serial3.begin(9600);
  pinMode(LED, OUTPUT);
  digitalWrite(LED, LEDst);
  pinMode(CH_PD_8266, OUTPUT);
  digitalWrite(CH_PD_8266, HIGH);
}

void loop() {
  while (Serial.available() > 0) {
    char a = Serial.read();
    Serial3.write(a);
  }
  
}

void serialEvent3() {
  while (Serial3.available() > 0) {
    char a = Serial3.read();
    Serial.write(a);
    ToggleLED();
  }
}

void ToggleLED(){
  digitalWrite(LED, LEDst = !LEDst);
}

Next:
- Arduino Due + ESP8266 - to Join AP