diff --git a/LaserClock/LaserClock.ino b/LaserClock/LaserClock.ino
index ec86da0..991d688 100644
--- a/LaserClock/LaserClock.ino
+++ b/LaserClock/LaserClock.ino
@@ -3,9 +3,14 @@
  *
  * Program for a binary laser clock
  *
- * Setup: a Button on pin 12, Led pin 13, Laser / LED on pin 2-11 needs to be pwm!
+ * Setup: a Button on pin 12, Led pin 13, Laser / LED on pin 2-11 needs to be pwm! RTC-Modul DS3231 required
  *
  */
+#include <Wire.h>
+#include "DS3231.h"
+
+DS3231 clock;
+
 #define pressed digitalRead(12) == LOW
 
 //pins for hour display
@@ -13,21 +18,10 @@ const unsigned char H[] = {8,9,10,11};
 //pins for min display
 const unsigned char M[] = {2,3,4,5,6,7};
 
-//how long takes a minute in ms?
-//const unsigned int mindelay = 60000;
-const unsigned int mindelay = 59000;
 //intensity of laser, when "off": 0 -> 0% on; 255 -> 100% on
 const unsigned int offtime = 160;
 
-//current time
-unsigned char min = 0;
-unsigned char hour = 0;
-
-//last time the minute changed
-unsigned long lastmin;
-
-//remove this line to enable Serial
-#define nolog
+bool houtremp;
 
 void set(const unsigned char pin, bool on) {
   if(on)
@@ -48,58 +42,50 @@ void write(unsigned char m = 255, unsigned char h = 255) {
     set(H[i], h & (1 << i));
 //    analogWrite(H[i], (h & (1 << i)) ? 255 : offtime);
   }
-  #ifndef nolog
-  //send data to Serial
-  Serial.print(hour);
-  Serial.print(":");
-  Serial.println(min);
-  #endif
 }
 
-//add one minute to the time
-void countTime() {
-  if(60 == ++min) {
-    min = 0;
-    if(13 == ++hour) {
-       hour = 1;
-    }
-  }
+inline void writeTime() {
+  write(clock.getMinute(), clock.getHour(houtremp, houtremp));
 }
 
 void setup() {
   pinMode(13, OUTPUT);
-  #ifndef nolog
-  Serial.begin(9600);
-  #endif
-  //Setup pins
- for(unsigned char m = 0; m < 6; m++) {
-  pinMode(M[m], OUTPUT);
- }
- for(unsigned char h = 0; h < 4; h++) {
-  pinMode(H[h], OUTPUT);
- }
- pinMode(12, INPUT_PULLUP);
- write();
- while(!pressed) delay(5);
 
- //setup time
- char mode = 0;//mode = 0-> set hour, mode = 1 -> set min, mode = 2 -> exit setup
- bool pres = false;//was button pressed
- unsigned long timeout = millis();
- while(mode < 2) {
-  if(pressed) {//button is pressed
+  //setup clock modul
+  Wire.begin();
+  clock.setClockMode(true); //set 12h format
+  clock.turnOffAlarm(1);//disable Arlam
+  clock.turnOffAlarm(2);
+  
+  //Setup pins
+  for(unsigned char m = 0; m < 6; m++) {
+   pinMode(M[m], OUTPUT);
+  }
+  for(unsigned char h = 0; h < 4; h++) {
+   pinMode(H[h], OUTPUT);
+  }
+  pinMode(12, INPUT_PULLUP);
+  write();
+  while(!pressed) delay(5);//wait for press
+
+  //setup time
+  char mode = 0;//mode = 0-> set hour, mode = 1 -> set min, mode = 2 -> exit setup
+  bool pres = true;//was button pressed
+  unsigned long timeout = millis();
+  writeTime();
+  while(mode < 2) {
+   if(pressed) {//button is pressed
     if(!pres) {//button was not pressed before
       timeout = millis();//reset timeout
       pres = true;
       if(mode == 0) {//count hour
-        if(++hour == 13)
-          hour = 1;
+        byte hour = clock.getHour(houtremp, houtremp)+1;
+        clock.setHour(hour == 13 ? 1 : hour);
       } else {//count min
-        min ++;
-        if(min == 60)
-          min = 0;
+        byte minute = clock.getMinute()+1;
+        clock.setMinute(minute == 60 ? 0 : minute);
       }
-      write(min, hour);
+      writeTime();
     }
   } else {
     pres = false;
@@ -112,33 +98,25 @@ void setup() {
       write();
       delay(300);
     }
-    write(min, hour);
+    writeTime();
     ++mode;//next mode
     //reset timeout
     timeout = millis();
   }
   delay(50);
  }
- lastmin = millis();
 }
 
 void loop() {
-  if((millis() - lastmin) >= mindelay) {
-    //update min
-    countTime();
-    write(min, hour);
-    lastmin += mindelay;
-  } else {
-  #ifndef nolog
-    Serial.print(millis()-lastmin);
-    Serial.print(" ");
-    Serial.println(millis()-lastmin >= mindelay);
-  #endif
-  }
+  //update min
+  byte hour = clock.getHour(houtremp, houtremp);
+  if(hour > 12)
+    hour -=12;
+  clock.setHour(hour);
+  write(clock.getMinute(), hour);
+  
   //let the led blink
-  if(millis()/1000 % 2 == 0) {
-    digitalWrite(13, HIGH);
-  } else
-    digitalWrite(13, LOW);
-  delay(50);
+  digitalWrite(13, millis()/1000 % 2 == 0);
+    
+  delay(500);
 }