The same starting point.

INCLUDE — our servo helper.

Load the header. Create a Servo object named myServo — our named “box” for controlling this servo.

// INCLUDE
#include <Servo.h>  // The helper control class.
Servo myServo;      // Create our named Servo object.

DECLARE — which pin?

Name the pin that sends the servo control pulses.

// DECLARE pins
const int servoPin = 9;  // Servo signal pin.

DECLARE — our ranges.

Name the library defaults, the proposed test limits, and the angle endpoints.

// DECLARE vars
const int baseMinPwm = 544;
const int testMinPwm = 400;
const int baseMaxPwm = 2400;
const int testMaxPwm = 2500;
const int minAngle = 0;
const int maxAngle = 180;

The Pwm values are pulse widths in microseconds. Here the proposed lower test value is 400 µs. These test limits are guesses, not confirmed safe endpoints for your servo.

INIT — start the terminal and attach the servo.

Start Serial, tell myServo which pin carries its signal, and print a welcome message.

// INIT
void setup() {
  Serial.begin(9600);         // Start the log terminal.
  myServo.attach(servoPin);   // Tell myServo which pin sends its signal.

  // Just a nice user message...
  Serial.println("--- Servo Calibration Test ---");
  delay(1000);
}

Match the Serial Monitor to 9600 baud. With attach(servoPin), the library uses its default 544–2400 µs limits and clamps commands to that range. Declaring testMinPwm and testMaxPwm does not change those limits; a wider range needs explicit configuration after checking the servo’s specifications.