For audio debug, added support for 12KHz sample rate and configurable audio frequency step.
In configure_beep (tone_gen), revert to start sampling the sine wave at 0 for frequencies below sample_rate/4 (trying to avoid a tiny pop in the speaker when the beep starts, yet still make sure there are non-zero samples at high frequencies)
For audio debug, added support for 12KHz sample rate and configurable audio frequency step.
In configure_beep (tone_gen), revert to start sampling the sine wave at 0 for frequencies below sample_rate/4 (trying to avoid a tiny pop in the speaker when the beep starts, yet still make sure there are non-zero samples at high frequencies)