Getting issues while using SoftwareSerial

Question

I am trying to read string send from esp8266 esp01 to Arduino mega. When I use normal Rx and Tx ports, it works properly but when i am initializing new serial port using SoftwareSerial then nothing is being shown on the serial monitor.

Please help me as i have been stuck and trying to solve this for weeks now. Below are the code for esp8266 and Arduino mega

Code for ARDUINO MEGA

#include<SoftwareSerial.h>

SoftwareSerial myS(4,5);

String data="true";

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
myS.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  if(myS.available()){
  data=myS.readString();
  }
  Serial.println(data);
  //Serial.write(data);
  delay(2000);
}

Code for ESP8266

void setup() {
  Serial.begin(9600);     // Initialize the Serial interface with baud rate of 9600
}

// the loop function runs over and over again forever
void loop() {  
  if(Serial.available()>0)    //Checks is there any data in buffer 
  {
    Serial.print("We got:");
    Serial.print(char(Serial.read()));  //Read serial data byte and send back to serial monitor
  }
  else
  {
    Serial.println("Hello World..."); //Print Hello word every one second
    delay(1000);                      // Wait for a second
  }
}

Moreover, i have tried read() as well instead of readString(), but it does not work either. I have also tried switching Rx and TX pins meaning connecting Rx->Tx, Tx->Rx and vice versa i.e. Rx->Rx and Tx->Tx, but it does not work in any of the case. Any help or suggestion will be appreciated. Thanks

Rx->Tx is correct, not the other way around. Also, the atmega2560 has more serial interfaces, so softwareserial is not a good choice — Sim Son
– Sim Son, Commented Jul 25, 2019 at 9:39

Majenko · Accepted Answer · 2019-07-25 10:35:37Z

SoftwareSerial only works on a few select GPIO pins on the Mega. Specifically those pins that have PCINT on them.

But that is irrelevant. There is no reason to use SoftwareSerial on a Mega except in exceptional circumstances. You have four hardware UARTs on the Mega, so there is no call to use SoftwareSerial. Use the real UART pins and objects:

Serial -> RX(0) / TX(1)
Serial1 -> RX1(19) / TX1(18)
Serial2 -> RX2(17) / TX2(16)
Serial3 -> RX3(15) / TX3(14)

Just replace all references in your code to the SoftwareSerial instance with Serial1 (delete the #include and the object instance constructor) and use TX1 and RX1 to connect your module:

String data="true";

void setup() {
    // put your setup code here, to run once:
    Serial.begin(9600);
    Serial1.begin(9600);
}

void loop() {
    // put your main code here, to run repeatedly:
    if(Serial1.available()){
        data=Serial1.readString();
    }
    Serial.println(data);
    //Serial.write(data);
    delay(2000);
}

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