The Arduino Servo library: move a hobby servo to an angle

// Servo sweep: the horn swings to 0, 90 and 180 degrees, then sweeps back.
//
//   servo brown (GND)   -> GND
//   servo red (VCC)     -> 5V
//   servo orange (PWM)  -> pin 9
//
// A hobby servo turns to an angle and holds it. It reads the angle from the
// width of a pulse sent fifty times a second: about 0.5 ms is one end, about
// 2.4 ms the other. The Servo library sends that pulse for you; write(angle)
// only changes how wide it is.
//
// The horn needs time to get there. This one moves about 60 degrees in a
// tenth of a second, so each jump waits a second before the next.

#include <Servo.h>

Servo horn;

void moveTo(int angle) {
  horn.write(angle);
  Serial.print("angle ");
  Serial.println(angle);
}

void setup() {
  horn.attach(9);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: servo sweep");
}

void loop() {
  moveTo(0);
  delay(1000);
  moveTo(90);
  delay(1000);
  moveTo(180);
  delay(1000);
  // A slow sweep back, one degree at a time.
  for (int angle = 180; angle >= 0; angle--) {
    horn.write(angle);
    delay(10);
  }
  Serial.println("swept back to 0");
  delay(1000);
}