servo_tester.ino

#include <Servo.h> 

Servo myservo;

void setup() {
  Serial.begin(9600);
  myservo.attach(7);
  myservo.writeMicroseconds(1500);
}

void loop() {
  while (Serial.available() > 0) {
    int microsec = Serial.parseInt();

    if (Serial.read() == '\n') {
      microsec = constrain(microsec, 1000, 2000);
      myservo.writeMicroseconds(microsec);
      Serial.println(microsec);
    }
  }
}