#include <SoftwareServo.h>
#define knob_pin A1
SoftwareServo servo;
void setup () {
  servo.attach (0);
}
void loop () {
  int anav, angle;
  anav = analogRead(knob_pin);
  if(anav < 180) anav=180;
  if(anav > 834) anav=834;
  angle = (anav - 180) / 3.63; //map 180~834 to 0~180
  servo.write (180 - angle);
  delay (1);
  SoftwareServo::refresh();