machines/systems/flexibot/docs/marlin/_gcode/M303.md

tag	title	brief	author	requires	group	codes	notes	parameters	examples
m0303	PID autotune	Auto-tune the PID system to find stable values.	thinkyhead	PIDTEMP|PIDTEMPBED	thermal	M303	Requires `PIDTEMP` or `PIDTEMPBED`. View current PID values with [`M503`](/docs/gcode/M503.html). If `EEPROM_SETTINGS` is enabled, all PID values are saved with [`M500`](/docs/gcode/M500.html), loaded with [`M501`](/docs/gcode/M501.html), and reset with [`M502`](/docs/gcode/M502.html).	tag optional description values E true Hotend index (-1 for heated bed). Default 0. tag type index int tag optional description values C false Cycles. At least 3 cycles are required. Default 5. tag type count int tag optional description values S false Target temperature tag type temp float tag optional description values U false Use PID result. (Otherwise just print it out.) tag type flag bool tag optional description values D false Toggle activation of `PID_DEBUG` output. tag type flag bool tag optional description values D false Toggle PID debug output on / off (and take no further action). (Requires `PID_DEBUG`) tag action	pre code Auto-tune hotend at 210 °C for 8 cycles: M303 E0 C8 S210 pre code Auto-tune bed at 60 °C for 8 cycles: M303 E-1 C8 S60

This command initiates a process of heating and cooling to determine the proper PID values for the specified hotend or the heated bed.