updateFrequency method
Update the main frequency directly (for controller-to-controller calls).
Used by levitation's playFrequency() when the generator is already running.
Implementation
void updateFrequency(double freq) {
if (_sineEngine.multiFrequencyMode) {
_sineEngine.frequencySub = freq;
} else {
currentFreq.value = freq;
_applyEffectiveFrequency();
}
}