Firmware 3.5.1-FINAL for Original Prusa i3 MK3/MK2.5 MMU2  

Jakub Dolezal

UPDATE: final version 3.5.2 is out

Hi guys,
new firmware 3.5.1-FINAL is out! This is a final release recommended to all users 😎

What is new?

- Button click fix
- M220 speed factor
- Z-levelling fix (MK3)
- Pause print -> stop print fix

Detailed description of changes:

Button click fix
The function for button press evaluation and debouncing was modified in previous firmware version to make the code more accessible for the future. However, this code improvement introduced a bug which could cause that some fullscreen messages which waited for the user to press the button were skipped. This has been fixed.

M220 speed factor
On multi-material printers, speed factor is currently set to 100 % before filament change by Slic3r PE. This ensures that filament change will proceed with defined speed and thus higher reliability.
There is now a possibility to save and restore speed factor on MK2.5 and MK3 printers using the following G-codes:
M220 Sxxx sets speed factor
M220 B sets backups current speed factor
M220 Sxxx B sets speed factor and backups current speed factor
M220 R restore saved speed factor
These M-codes are the same as on MK2 printers with Firmware 3.1.0 and allows Slic3r PE to backup speed factor set by the user (by rotating the knob on the printer) before filament change and then to restore is when filament change if finished. This will fix issues #1364 and #1208.

Z-levelling fix (MK3)
Z-levelling function introduced in previous Firmware 3.5.0 could repeatedly fail (X-axis staying at the top with a message "Some problem encountered, Z-leveling enforced ...") on MK3 printers under certain conditions. This has been fixed.

Pause print -> stop print fix
Stopping paused print could lead to behaviour when some movements were missing during new print or first layer calibration. This has been fixed.

Supported printers:
Original Prusa i3 MK3
Original Prusa i3 MK3 Multi Material 2.0
Original Prusa i3 MK2.5
Original Prusa i3 MK2.5 Multi Material 2.0

Download link:

Firmware flashing guide:

Please report any bug here:

As always, we wish you happy printing and look forward to your feedback!

Assembly manuals / Knowledge Base
The guy behind Prusa assembly manuals......
Posted : 20/12/2018 2:12 pm
Reputable Member

Could a post processing script be added which searches and replaces "M220 S35" with "M220 S100" so that TPU will print without having to adjust the speed manually after every filament change?

I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list....
Posted : 27/12/2018 9:04 pm
Grandpa Joe
Eminent Member

Is the MMU2 being shipped yet?? I have been waiting - - - - - but glad you are improving and getting all the bugs worked out. But - if there is new firmware - is it fixed and shipping???

Posted : 29/12/2018 2:58 am
Noble Member

im just now starting to use this firmware. so im guessing a new version will come out tomorrow.

so far working fine.

I have a Prusa,therefore I research....
Posted : 28/01/2019 5:21 am
Noble Member

hey I just noticed if you save speed% from the operator panel, its saves the new speed. nice.

any way to get it to save each filaments manual speed? is that a "bit" thing or a "memory" thing?

I have a Prusa,therefore I research....
Posted : 29/01/2019 11:35 am
Jakub Dolezal

UPDATE: final version 3.5.2 is out

Assembly manuals / Knowledge Base
The guy behind Prusa assembly manuals......
Posted : 20/02/2019 11:46 am

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