#include "FlexiTimer2.h"

const long Tp = 500;
const int led_pin = 3;

void setup() {
  Serial.begin(9600);

  pinMode(led_pin, OUTPUT);

  FlexiTimer2::set(Tp, 1.0/1000, flash);
  FlexiTimer2::start();
}

void loop() {

}

void flash() {
  static boolean output = HIGH;
  
  digitalWrite(led_pin, output);
  output = !output;
}