#include <TimerOne.h>

int a = 0;
int spd=500; //0~511の値にする

void setup(){
  Serial.begin(9600);
  Timer1.initialize(500000);// initialize timer1, and set a 1/2 second period
  Timer1.pwm(9, 0);                // setup pwm on pin 9, 50% duty cycle
  Timer1.attachInterrupt(callback);  // attaches callback() as a timer overflow interrupt
  pinMode(1,OUTPUT); //信号用ピン
  pinMode(2,OUTPUT); //信号用ピン
  motor_stop();
}

void callback(){
    if(Serial.available()>0){//データの読み込み
      a=Serial.read();
    }
}

void test_LED(){
  digitalWrite(13,HIGH);
  delay(500);
  digitalWrite(13,LOW);
}

void motor_stop(){
  digitalWrite(1,LOW);
  digitalWrite(2,LOW);
  Timer1.pwm(9,512);                // setup pwm on pin 9, 50% duty cycle
  test_LED();
}

void motor_go(){
  digitalWrite(1,LOW);
  digitalWrite(2,HIGH);
  Timer1.pwm(9,512);                // setup pwm on pin 9, 50% duty cycle
  test_LED();
}

void motor_go2(){
  digitalWrite(1,LOW);
  digitalWrite(2,HIGH);
  Timer1.pwm(9,512);                // setup pwm on pin 9, 50% duty cycle);
  test_LED();
  delay(10);
  test_LED();
}

void loop(){
  if(a!=0){
    switch(a){
      case 'a':
        motor_go();
        delay(1000);
        break;

      case 'b':
        motor_go2();
        delay(1000);
        break;
    }
  }
  Timer1.pwm(9,0);                // setup pwm on pin 9, 50% duty cycle);
}