5.1.0-alpha1 Firmware for Original Prusa MINI

Es scheint so, dass Prusa am Zugzwang ist und handeln wird, denn diese haben vor einigen Stunden eine neue Firmware für den Prusa Mini in einer Alpha Version veröffentlicht. BambuLab wird morgen sein neues Produkt vorstellen und viele spekulieren auf ein kleineres Modell was in meinen Augen auch Sinn macht. Denn BambuLab möchte bei den großen wie Voron, Prusa und RatRig mitspielen.

Denn diese Firmen haben erfolgreich einen kleineren Drucker veröffentlicht, welche zu einem günstigeren Preis zu bekommen ist. Hierbei spricht man wohl vom BambuLab A1, welche knapp 299 Dollar kosten soll. Sollte es so sein und der ganze Aufbau innovativ sein, dann kann man schon jetzt sagen, dass BambuLab wieder einen Geniestreich geschafft hat.

Die neue Firmware für den Prusa Mini hat es in sich, denn es wird Input Shaping aktiviert und auch Prusa Connect wird verfügbar sein. Was mich aber ein wenig stört, dass Prusa ein Benchy zum Download anbietet, welches innerhalb von 16 Minuten fertig sein soll. Schaut man sich aber die Codes an, sieht man genau, warum. Denn die ganze Struktur wurde auf das Minimum gehalten und das machen derzeit sehr viele Firmen, nur um besser dastehen zu können.


  • One codebase to rule them all
  • Input Shaper functionality added
  • Prusa Connect support
  • Known bugs

This is the first public release of the 5.1.0-alpha1 firmware for the Original Prusa MINI+ & MINI. Since both printers share the same motherboard (Buddy), the release notes will describe the changes for MINI only. This is an alpha release dedicated only to experienced users. Features in this firmware are still being developed and may not perform as expected. Should you encounter any bugs or issues with the printer’s performance, please report them via GitHub or in our forums.

The Original Prusa XL (single and multi-tool) Input Shaper internal tests are underway, and a public testing release is expected soon. The multi-board architecture of the XL is more complex and requires additional work.

One codebase to rule them all

Starting with this release, the MINI will be using the same firmware codebase as the Prusa MK4. The MINI team was working on implementing the new features from the MK4 branch for several months – the biggest challenge was to adapt the code for a different CPU and lower RAM size. It couldn’t have been done without heavy optimizations.

As a result, your MINI will get several major improvements. To name a few features:

  • Faster printing thanks to:
    • Input shaper
    • Pressure Advance
    • Precise Stepping
  • User Interface refresh
  • Prusa Connect support
  • Latest PrusaLink

We like to support our machines for many years after launch with regular updates and improvements. We’re pretty sure that with this firmware release, your MINI will feel like a brand new printer.

Please note, that this alpha firmware for MINI utilizes a different QOI image format (previously PNG). G-codes with the new thumbnails can be prepared in the upcoming PrusaSlicer 2.6.2.

Input Shaper and Pressure Advance

Similarly to the MK4, the 5.1.0-alpha1 firmware for the MINI comes with three new major additions – Input Shaper, Pressure Advance and Precise Stepping.

Input Shaper is a feature designed to reduce ringing (also known as echoing or ghosting) and overshoots during printing by smoothing out the accelerations and decelerations of the printer’s movements. It works by analyzing the printer’s movements and applying a filter to the input signals to reduce the ringing effect. Thanks to faster travel speed and accelerations, it can also minimize stringing. It also enables faster printing.

Pressure Advance is another important addition to the firmware’s set of features. This function aims to improve the quality of printed parts by compensating for the pressure changes in the nozzle during printing. Pressure Advance together with Input Shaper enables the printing of better-looking models, reducing ringing, overshoots and issues with inconsistent filament extrusion. They also enable faster printing.

Precise stepping is a new implementation of stepper, that allows precise timing of motor steps. It was a necessary prerequisite for both Input shaper and Pressure advance.

Firmware update instructions

Make sure you are running firmware 4.4.1, see the release notes for firmware files and instructions. Once the 4.4.1 is installed proceed to flashing the 5.1.0-alpha1 firmware. Note that the upgrade might take longer than usual.

You will need PrusaSlicer 2.6.1 (or newer) and the special MINI Input Shaper profiles to slice your own objects with Input Shaper and Pressure Advance support. If you don’t see an automatic pop-up window with updated configuration files when you launch PrusaSlicer, use Configuration -> Check for Configuration Updates menu to download the new profiles. Then go to Configuration -> Configuration Wizard to add the “Original Prusa MINI & MINI+ Input Shaper (Alpha)”.

To download the latest version of PrusaSlicer, please visit prusaslicer.org.

Dedicated forum section and testing G-Code

We have created a new subsection in the MINI+ forum, where we can together discuss all the things related to Input Shaper. Our support team will be there, collecting feedback, and answering questions. Share your successful prints, ask questions, and report bugs – please check the list of known issues at the end of the release notes before you post.

We have also prepared a pre-sliced Benchy G-Code for you to test the increased speeds, see the YouTube video. Please use standard PLA (e.g. Prusament PLA Galaxy Black) instead of various blends, silks, -fills and other “non-standard” PLA variants that require different print settings. Read the instructions thoroughly before you start printing. The G-code is attached below the release notes.

Forum link: prusa.io/mini-input-shaper

G-Code changes

You can use custom G-Codes to fine-tune various Input Shaper and Pressure Advance parameters – please see the MK4 5.0.0-alpha1 firmware release notes for more information.

Preparation and Troubleshooting

The fastest 3DBenchy G-Code will be printed several times faster compared to the previous MINI+ firmware and stock profiles. To achieve the best possible print performance, we strongly suggest performing basic maintenance on the MINI+ before you start. Make sure the belts on the X and Y axes are not loose, the nozzle is in good shape, and there’s no debris on the smooth rods.

If you encounter layer shifts, the usual cause are loose belts. Adjust the belt tension according to our MINI guide.

If you want to revert back to stable firmware, please follow the instructions in the handbook. In short: place the stable firmware version on a USB drive, insert it into the printer and during the startup (when the logo is shown), press and hold the knob to force a firmware installation screen. Flash the stable firmware and perform a full factory reset.

Printing your own models

Make sure you’re running PrusaSlicer 2.6.1 (or newer) and you’re using the MINI Input Shaper print profile
When printing your own objects, please consider the following:

  • This is an alpha release and we continue to fine-tune the profiles. Some materials might be missing at the moment. Feel free to experiment and add them, if you want
  • When printing large and heavy objects, PrusaSlicer / MINI firmware will automatically adjust the speeds as the height/weight of the object increases during printing
  • You may consider increasing the nozzle temperature slightly if the results with stock speeds are not optimal

Prusa Connect support

Thanks to the new firmware, the MINI can fully utilize the Prusa Connect, therefore you are now able to send G-codes and control the printer remotely. To learn more about Prusa Connect, please visit this article.

Known bugs

  • Using Prusa Connect can occasionally lead to BSOD.
  • If the ESP Wi-Fi is outdated, the “update” message can become unresponsive. The workaround is to insert a USB drive with any G-code and then update the ESP from the “Network” menu.
  • Due to the major changes to the code, the Octoprint is currently not working, however, we are already working on the fix.

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