int led_status[3] = {0, 0, 0};
int led_enabled[3] = {1, 1, 1};
unsigned long X;

void update_led()
{
  digitalWrite(2, led_status[0]);
  digitalWrite(3, led_status[1]);
  digitalWrite(4, led_status[2]);
}

void setup() 
{
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  Serial.begin(9600);
  Serial.println("Ketiga LED akan berkedip dengan rate yang berbeda.");
  Serial.println("Blinking bisa di RUN/STOP dengan perintah melalui Serial Monitor.");
  Serial.println("Send 1 untuk RUN/STOP LED 1.");
  Serial.println("Send 2 untuk RUN/STOP LED 2.");
  Serial.println("Send 3 untuk RUN/STOP LED 3.");
  Serial.println("https://blog.teknikelektrolinks.com");
}

void loop()
{
  if (Serial.available())
  {
    char ch = Serial.read();
    if (ch=='1' || ch=='2' || ch=='3')
    {
      ch = ch - 49;
      led_enabled[ch] = !led_enabled[ch];  
      Serial.print("LED "); Serial.print(ch+1); Serial.print(" ");
      Serial.println(led_enabled[ch] ? "enabled" : "disabled");
    }
  }
  
  X++;
  if (led_enabled[0] && X%1000 == 0) led_status[0] = !led_status[0];
  if (led_enabled[1] && X%3000 == 0) led_status[1] = !led_status[1];
  if (led_enabled[2] && X%6000 == 0) led_status[2] = !led_status[2];
  
  update_led();
}