Motor calibration for modular robot

I just made a simple tutorial that can be used for motor calibration when assembling modular robots.

// Calibration tool for modular robots
// Copyright Filippo Sanfilippo
#include <SoftwareServo.h>

SoftwareServo servo;

void setup()
{
  servo.attach(3);
  servo.setMaximumPulse(2200);
  Serial.begin(9600);
  Serial.println("Ready");
}

void loop()
{
  static int value = 0;

  if ( Serial.available()) {
    char ch = Serial.read();
    switch(ch) {
      case 'a':
        value = 0;
        servo.write(value);
        Serial.println("0 degrees");
        break;
      case 'b':
        value = 90;
        servo.write(value);
        Serial.println("90 degrees");
        break;
      case 'c':
        value = 180;
        servo.write(value);
        Serial.println("180 degrees");
        break;
    }
  }
  SoftwareServo::refresh();
}