Simon - showSequence

///////////////////////////////////////////////////////////////////////////////
void showSequence() {
  // Set tone playback duration based on current sequence length
  uint16_t toneDuration;
  if (currentStep<=5) {
    toneDuration = 420;
  } else if (currentStep<=13) {
    toneDuration = 320;
  } else {
    toneDuration = 220;
  }

  // Play back sequence up to current step
  for (int i=0; i<currentStep; i++) {
    delay(50);
    indicateButton(simonSequence[i], toneDuration);
  }
}