New solid Heartbeat code

[structure7]

Do it:

WidgetLED led1(V18); // Heartbeat

void setup()
{
  timer.setInterval(5000L, sendHeartbeatOn); // Blinks Blynk LED to reflect online status
}

void sendHeartbeatOn()
{
  led1.on();
  timer.setTimeout(2500L, sendHeartbeatOff);
}

void sendHeartbeatOff()
{
  led1.off();
}