#include <Servo.h>

int servoPin = 9 ;
int servoPos ;
Servo servo1;
int dt = 1000 ;

void setup() {
  
servo1.attach (servoPin);
servo1.write(0);
}

void loop() {
  servo1.write(0);
  delay(dt);
  servo1.write(90);
  delay(dt);
  servo1.write(180);
  delay(dt);
  
}