machines/systems/flexibot/docs/marlin/_gcode/M300.md

tag	title	brief	author	requires	group	codes	notes	parameters	examples
m0300	Play Tone	Play a single tone, buzz, or beep.	thinkyhead	SPEAKER	lcd	M300	Requires `SPEAKER` to play tones (not just beeps). In Marlin 1.0.2, playing tones block the command queue. Marlin 1.1.0 uses a tone queue and background tone player to keep the command buffer from being blocked by playing tones.	tag optional description values P true Duration (1ms) tag type ms int tag optional description values S true Frequency (260Hz) tag type Hz int	pre code Play a tune. M300 S440 P200 M300 S660 P250 M300 S880 P300

Add a tone to the tone queue.