#include <Servo.h>
Servo myservo;
int a = 90;
 char val;

 void setup() {
 Serial.begin(9600); // Start serial communication at 9600 bps
 myservo.attach(3);
 myservo.write(a);
 }


 void loop() {
 while (Serial.available()) { // If data is available to read,
 val = Serial.read(); // read it and store it in val
 }
 if (val == 'H') {
  a = a - 1;
  if(a < 0 )a=0;
  myservo.write(a);
 } if(val == 'L'){
  a = a + 1;
  if(a > 180)a = 180;
  myservo.write(a);
 }

 delay(100);
 }