int rot_pin = 5;
int gruen_pin = 6;
int blau_pin = 7;

// common cathode

void setup()
{
   pinMode(rot_pin,OUTPUT);
   pinMode(gruen_pin,OUTPUT);
   pinMode(blau_pin,OUTPUT); 
}

void loop()
{
   setColor(255,0,0);
   delay(1000);
   setColor(0,255,0);
   delay(1000);
   setColor(0,0,255);
   delay(1000);
   setColor(255,255,0);
   delay(1000);
   setColor(40,0,40);
   delay(1000);
   setColor(0,255,255);
   delay(1000);   
}

void setColor(int rot, int gruen, int blau)
{
   analogWrite(rot_pin,rot);
   analogWrite(gruen_pin,gruen);
   analogWrite(blau_pin,blau);
}