1.0.6-RC2 Firmware for MMU2S

Summary:

• Improved stealth mode
• Unload speed decreased
• Filament cut feature
• Disabled unwanted selector movement
• Automatic idler disengagement

Detailed description of changes:

Improved stealth mode

The value of the idler holding current was increased in order to ensure its proper motion. Low idler holding current value might lead to an idler misalignment. For MK3S MMU2S the idler holding current values are the same for Stealth and Normal mode. For MK2.5S MMU2S only stealth mode is available.

During acceleration and deceleration, the current value drops or increases. This is directly affecting the value of the torque, which might be low in some situations and thus the motor doesn't have enough "power" to load/unload the filament. To avoid this situation we are changing the value of constant in the Trinamic driver, which results in sufficient current and torque under any type of movement.

Similarly in Stealth mode, for some movements, the unit switches temporarily to the Normal mode, which provides higher current and torque. As soon as the torque is no longer needed, the mode is switched back to the Stealth.

Unload speed decreased

As explained in the paragraphs above, there were some scenarios, where the motors might not have enough torque to load/unload the filament properly. To avoid any issues, unload speed is slightly decreased to maintain a higher torque value.

Filament cut feature

This feature will be utilizing the included blade to cut the unwanted tips of the filament. The current release contains improvement in the situation when the printer recognizes a failed cut. After the filament is cut, printer tries to load the filament and trigger the F.I.N.D.A. sensor in the MMU2S unit, in case this operation fails, all movable parts of the MMU2S unit are rehomed to ensure proper alignment.

The filament cut feature is disabled for now, we are still working on it. We plan to enable it in a future firmware release.

Disabled unwanted selector movement (during fail state)

When the MMU2S experiences a filament load/unload fail, it asks the user to solve the issue. After resolving the problem, the user has to confirm it by pushing the right button on the unit. However, if the right button was pressed for a longer period, the unit also moved the selector to the next filament. The current release is changing this behavior and selector can be moved only after the right button is pressed again.

Automatic idler disengagement

During the filament load, the MMU2S unit is pushing the filament using the idler until getting information from the extruder (IR-sensor). This information was sometimes lost and the idler was still pushing even when no longer needed. In the current release as soon as the preset distance is loaded through the MMU2S unit, the idler automatically disengages and returns only when prompted by the extruder (IR-sensor).

Thanks to Brian Smith for contributing to the code, more information in Make sure idler disengages