public function pulse($iterations = null, $interval = 1, $duty = 0.5)
{
$this->on();
$on_time = $interval * $duty;
$this->pin->getBoard()->getLoop()->addTimer($on_time, [$this, 'off'])->getLoop()->addPeriodicTimer($interval, function (TimerInterface $timer) use(&$iterations, $on_time) {
if ($iterations !== null && --$iterations === 0) {
$timer->cancel();
return;
}
$this->on();
$timer->getLoop()->addTimer($on_time, [$this, 'off']);
});
}
