// serial connection - serial monitor

void setup() {
  Serial.begin(9600);    // setting up baud rate
                         // initialize serial connection
  Serial.println("Booting up ..... ");

  digitalWrite(LED_BUILTIN, LOW);
} 


String command;
int incomingByte = 0;
int _led = 0;
const int BUFFER_SIZE = 50;
char buffer[BUFFER_SIZE];



void loop() {

  Serial.println("esp32io.com");   // mit Zeilenvorschub
  Serial.print("text in");
  Serial.println("gleicher zeile");  // ohne Zeilenvorschub

  
  Serial.print("Was ist im buffer: ");
  Serial.println(Serial.available());  // is there something in the serial buffer, nothing=0, something!=0
  Serial.println();

  Serial.write(43);        // ASCII-Zeichen "+"
  Serial.write(45);        // write a byte with the value 45 => '-' character
  Serial.write('\n');      // write a newline character
  Serial.write("esp32 - GetStarted \n"); // write a string terminated by a newline character

  byte buf[] = {'A', 'r', 'd', 'u', 'i', 'n', 'o'};
  Serial.write(buf, 7);    // write an array


/*
  if (Serial.available()) {                          // if there is data comming function != 0
  Serial.print("Eingabe eines Textes: ");            // S T R I N G - R E A D 
  command = Serial.readStringUntil('\n');            // after ENTER the buffer will receive string
  Serial.println("eingegeben wurde: ");              // after ENTER Serial.available() != 0
  Serial.println(command);
  }
*/

/*
  if (Serial.available() > 0) {                        // check if data is available
    int rlen = Serial.readBytes(buffer, BUFFER_SIZE);  // read the incoming bytes:

    Serial.print("I received: ");                      // prints the received string/text
    for(int i = 0; i < rlen; i++)                      // single   C H A R  - R E A D
      Serial.print(buffer[i]);
  }
*/

 
/*
  if (Serial.available() > 0) {                  // check if data is available, Serial.available() = sum of input + \n
    incomingByte = Serial.read();                // read the incoming byte:
    
    Serial.print("I received: ");                // prints the received data, --byte-by-byte--
    Serial.println((char)incomingByte);          // single   C H A R  - R E A D
  }
*/

  
  _led = Serial.read();                      // read string until newline character;
    if (_led == '1') {
      digitalWrite(LED_BUILTIN, HIGH);       // turn on LED
      Serial.println("Turn LED ON");
    } else if (_led == '0') {                // single   C H A R  - R E A D
      digitalWrite(LED_BUILTIN, LOW);        // turn off LED
      Serial.println("Turn LED OFF");
    }
  



/*
Serial.read();
Serial.readBytes();
Serial.find();
Serial.end();          // disables serial communication, RX & TX can be used otherwise. Restart with Serial.begin()
*/

delay(2000);
}