#include <Adafruit_SoftServo.h>  

Adafruit_SoftServo myservo;

int pos = 0;    

void setup() {
  myservo.attach(PB0);
}

long int lastUpdate = 0;

void loop() {
  for (pos = 0; pos <= 180; pos += 1) { 
    // in steps of 1 degree
    myservo.write(pos);              
    myservo.refresh();               
    delay(15);                       
  }
  for (pos = 180; pos >= 0; pos -= 1) { 
    myservo.write(pos);              
    myservo.refresh();               
    delay(15);                       
  }
}