#include <SoftwareSerial.h>
 
#define MYPORT_TX 5  // D1  -> green    -> RXD der Gegenstelle
#define MYPORT_RX 4  // D2 <-  yellow  <-  TXD der Gegenstelle

SoftwareSerial myPort;
byte LED1 =  2;  // GPIO2  => D4 - onboard LED auf ESP8266 12E
byte LED2 = 16;  // GPIO16 => D0 - onboard LED auf NodeMCU Amica

void setup() {
  Serial.begin(9600); delay(2000); Serial.println("\n\n --- ESP8266-D1-SoftwareSerial-Test.ino ---\n");
  pinMode(LED1, OUTPUT);  digitalWrite(LED1, 0); //Aus
  pinMode(LED2, OUTPUT);  digitalWrite(LED2, 0); //AN  
  delay(1000);
  digitalWrite(LED1, 0);   digitalWrite(LED2, 1); 
  delay(10000);

  myPort.begin(9600, SWSERIAL_8N1, MYPORT_RX, MYPORT_TX, false);
  Serial.println("Teste SoftwareSerial ."); 
  while (!myPort) {
    digitalWrite(LED1, not digitalRead(LED1));
    Serial.print("."); 
    delay (500);
  } 
  Serial.println("\n OK");
  delay(10000);
  while (myPort.available()) myPort.read(); 
}
String eingabe;
void loop() {
  digitalWrite(LED2, not digitalRead(LED2));
  
  eingabe="";
  if (Serial.available()) {
      eingabe = Serial.readStringUntil('\r');
      eingabe.trim();  // entfernt \r\n, falls vorhanden
      myPort.println(eingabe); 
  }
  
  if (eingabe != "") Serial.println(String(eingabe.length()) + " : " + eingabe);
  while (myPort.available()) {
    Serial.write(myPort.read());
    digitalWrite(LED1, not digitalRead(LED1));
  }
  delay(100);
}