Logically invert the pin?

Unfortunately i don't have one...

I also found stm32's jshDelayMicroseconds function you were talking about earlier

void jshDelayMicroseconds(int microsec) {
    int iter = (int)(((long long)microsec * (long long)JSH_DELAY_MULTIPLIER) >> 10);
  //  iter -= JSH_DELAY_OVERHEAD;
  if (iter<0) iter=0;
  while (iter--) __NOP();
}

I see the logic of this function like this:

iter = microsec * (how_fast_mc_is / how_fast_it_should_be)

But i don't understand how to make this function work with nanoseconds.