#include "Servo.h"
Servo myServo;

const byte PinServo = A5;
const byte PinButUp = 9;
const byte PinButDn = 8;

int        ang = 90;    // define servo 

void setup() {
   Serial.begin(115200);
   Serial.println("button-servo");

   pinMode (PinButDn, INPUT_PULLUP);
   pinMode (PinButUp, INPUT_PULLUP);

   myServo.attach (PinServo);
   myServo.write (ang);      // set servo to initial value of ang
}

void loop() {
  if (LOW == digitalRead(PinButUp))  {
    if (ang < 180)          // increment ang if less than 180
      ang++;                // same as ang = ang + 1
  }
  else if (LOW == digitalRead(PinButDn))  {
    if (ang > 0)            // decrement ang if greater than zero
      ang--;
  }

  myServo.write (ang);      // set servo to value of ang

  delay (25);               // 25 msec delay, increament by 40 / sec
}