#include <waiter.h>

const byte ledPin = 13;
const clock_t flashTime = 2 * SEC;

waiter ledFlash;
bool ledState;

void setup() {
    pinMode( ledPin, OUTPUT );
};

void loop() {
    if( ledFlash.wait( flashTime ) ) {
        ledState = !ledState;
        digitalWrite( ledPin, ledState );
    }
};