#include <Arduino.h>
 
//Defines
#define Taster 13
#define Bit0 8
#define Bit1 9
#define Bit2 10
#define Bit3 11
 
//Globale Variable
byte zaehler = 1;
byte bitwert;
unsigned long Time;
unsigned int Interval;
bool richtungswechsel;
 
void setup() {
 
  Serial.begin(9600);
  pinMode(13, INPUT_PULLUP);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
 
  Time = millis();
  Interval = 1000;
 
}
 
void loop() {
 
  {
    if (digitalRead(Taster) == LOW)
      richtungswechsel = !richtungswechsel;
  }
 
  for (byte n =0; n <= 3; n++)
  {
    bitwert = (zaehler & (1<<n));
 
    if (bitwert)
      digitalWrite(n+8, HIGH);
    else
      digitalWrite(n+8, LOW);
  }
 
  {
    if(millis()-Time >= Interval)
    {
      if (richtungswechsel == LOW)
      {
          zaehler = zaehler << 1;
          if (zaehler == 16)
            zaehler = 1;
      }
      else
      {
        zaehler = zaehler >> 1;
          if (zaehler == 0)
            zaehler = 8;
      }
 
      Time = millis();
    }
  }
 
 
}