Persistence of Vision-Led-help-

hello, I want to paint with a led full circle.
begins with a painted like a pacman, remains open, then start
to increase the speed, and this opening begins to close,
but when this opening tends to SHUT, a turn off.

that is passed, any ideas? as you sack this effect, shutting
around when the circle is closed?

         volatile unsigned long timeold=0;
          volatile unsigned long new_time = 0;
          volatile unsigned long refreshEnd = 0;
          volatile unsigned long Refresh = 0;
          
          
           void setup(){
             pinMode(13, OUTPUT);   //led  
       


                     attachInterrupt(0, rpm, FALLING);

                     
          
          
          }
          
          void rpm(){


                     new_time=micros();
                     Refresh =  (new_time - timeold) ;
                     timeold =  new_time;
                     interruptHit =true;
                            
            }
          void loop() {
            
            
            if(   interruptHit ==true){
            
             // time delay Pacman
             refreshEnd=micros();
             while(  (micros() - refreshEnd)< 200 ) {;}
             // 
              
              digitalWrite(13, HIGH);   // set the LED on
              
             //time paint full circulo 
             refreshEnd=micros();
             while(  (micros() - refreshEnd)< Refresh ) {;}
             
             interruptHit =false;
             
            }else{
            
              digitalWrite(13, LOW);   // set the LED on
            }
            
            

         }

=(