Buko84 asked whether the M9's notification sounds can be made louder. There is
no volume setting because there is nothing to turn: the buzzer on these boards
is a bare piezo on a GPIO driven by tone(), a fixed-duty square wave, so
amplitude is simply whatever the part does at that pitch.
Frequency is the lever that does exist. A piezo is far louder near its mechanical
resonance, typically around 4 kHz, than at the 1 to 2.6 kHz the chime uses, so
"Loud alerts" in Settings, Sound plays the same three-note shape shifted into
that band. Same chime, so it still reads as the same alert rather than a new one,
and toggling it plays it so the difference is audible while the switch is still
under your finger.
Off by default and opt-in, because the exact resonant peak varies by part and
this has not been measured on an M9. Schema v55, field appended at the tail.
Built on all nine S3 envs and both ESP32-P4 targets.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
