Firmware retraction is an advanced feature implemented in this firmware and allows you to change retraction parameters on the fly while a printing is in progress.

Image from Sebastiaan Dammann - Adjustable retractions during printing

When tuning retractions, you can play with these parameters in the Tune menu:

• Temperature
• Amount of filament to retract
• The speed at which to retract
• An optional Z-hop
• The speed of the recover

Note that it may take a few moments for any changes to take effect. It is possible to preset the retractions in the Filament Settings menu.

For use Firmware Retract you must to instruct to your slicer to use G10/G11 g-codes instead the usual extruder movement commands. Some good information about how to enable firmware retract can be found here:

• Marlin documentation about firmware retract
• Using Firmware Retraction with Simplify3D
• For Cura you need the Printer Settings plugin
• Sebastiaan Dammann blog
• Slic3r and Marlin configuration for RepRap FW retraction

It is not necessary to add any code to your start g-code script, but for Super/PrusaSlicer you can add this g-code to preset the firmware retraction parameters to be the same as the setting of the slicer.

; Setup firmware retraction settings
M207 F{ retract_speed[0] * 60} S[retract_length_0] Z[retract_lift_0]
M208 F{ deretract_speed[0] * 60} S[retract_restart_extra_0]

Teaching Tech video about of firmware retraction feature: https://youtu.be/T4N59u4wm-Y