Startup sequence

When initialized, MMU sends

MMU => 'start\n'

We follow with

MMU <= 'S1\n'
MMU => 'okFirmware version\n'
MMU <= 'S2\n'
MMU => 'okBuild number\n'

#if (12V_mode)

MMU <= 'M1\n'
MMU => 'ok\n'

#endif

MMU <= 'P0\n'
MMU => 'FINDA status\n'

Now we are sure MMU is available and ready. If there was a timeout or other communication problem somewhere, printer will be killed.

Firmware version is an integer value, but we don't care about it
Build number is an integer value and has to be >=126, or =>132 if 12V mode is enabled
FINDA status is 1 if the filament is loaded to the extruder, 0 otherwise

Build number is checked against the required value, if it does not match, printer is halted.

Toolchange

MMU <= 'TFilament index\n'

MMU sends

MMU => 'ok\n'

as soon as the filament is fed down to the extruder. We follow with

MMU <= 'C0\n'

MMU will feed a few more millimeters of filament for the extruder gears to grab. When done, the MMU sends

MMU => 'ok\n'

We don't wait for a response here but immediately continue with the next gcode which should be one or more extruder moves to feed the filament into the hotend.

FINDA status

MMU <= 'P0\n'
MMU => 'FINDA status\n'

FINDA status is 1 if the is filament loaded to the extruder, 0 otherwise. This could be used as filament runout sensor if probed regularly.

Load filament

MMU <= 'LFilament index\n'

MMU will feed filament down to the extruder, when done

MMU => 'ok\n'

Unload filament

MMU <= 'U0\n'

MMU will retract current filament from the extruder, when done

MMU => 'ok\n'

Eject filament

MMU <= 'EFilament index\n'
MMU => 'ok\n'

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