6.2.0-alpha1 Firmware for Original Prusa MK4, MK4S, MK3.9, MK3.9S, MK3.5, MK3.5S, MINI & XL

Summary

• New features
  • Expanded GPIO functionality (MK4/S, MK3.9/S, MK3.5/S)
  • Toolhead and hardware menu overhaul
  • Improved filament management
  • Nozzle information for Prusa Connect
  • Japanese language support on MINI
  • Mapping screen from Prusa Connect
• Community Contributions
• Bug Fixes
  • Wi-Fi stability improvements
  • G-code transfer fixes
  • USB media prefetch
  • Improved preview loading during file transfer
  • MINI sensor update fix
  • Persistent Compatibility Mode
• Model changes
  • CoreXY model calculations

This is a public release of the 6.2.0-alpha1 firmware for the Original Prusa MK4/S, MK3.9/S, MK3.5/S, XL, and MINI+.

This is an alpha release intended for experienced users. The features in this firmware are still under development 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.

Please note that this is a testing firmware developed primarily on stock unmodified printers. In case you are running any 3rd party upgrade, exercise caution and let us know in case of any issues.

Translation Status

While all language variants are available, we acknowledge that the translations are not yet fully complete. This is not a bug, and full translation support will be added in a future update.

New Features

Expanded GPIO functionality

The GPIO functionality has been enhanced in this release. While M260 and M261 API was already introduced in version 6.1.2, we’ve now added dedicated support for the Prusa-specific GPIO expander through G-codes M262 - M265.
These new G-codes extend the control over the GPIO expander, making it more versatile and powerful as we now support input on GPIO, allowing users to trigger custom-defined macros in G-code format, up to 1024 bytes in size. Full details on this feature, along with G-code usage examples, are available in our GPIO article.

Toolhead and hardware menu overhaul

The toolhead and hardware menu has been reworked, allowing users to set specific parameters for each individual toolhead and also for all of them at once. This also includes checks for hardened or high-flow nozzles, ensuring that your toolhead is always properly configured.

Improved filament management

We’ve revamped the filament management system, offering more customization and control for users:

• Hide filaments: Users can now choose to hide any filament types from the menus (e.g. preheat menu, filament load menu, etc.)
• Reorder filament: You can now manually change the order in which filament types appear.
• User filaments: Introducing user-defined filament options for more personalized settings.
• Custom filament Settings: Ad-hoc definition can now be made during the filament loading process, allowing you to tweak parameters - depending on loaded material.
• Abrasive materials warnings: If you’re working with abrasive materials (e.g., carbon or glow-in-the-dark filaments) without a hardened nozzle, the printer will now provide a warning during filament loading or print start.
• Loaded filament display: A new menu option “Loaded filament(s)” shows what filament is currently in use. Filament categories are indicated as Preset, User-defined, or Custom. On the MINI, some information is hidden due to screen size constraints.

Nozzle information for Prusa Connect

We’ve integrated detailed nozzle data into Prusa Connect, ensuring that users can now view nozzle-related parameters for all tools directly from the Connect.

Japanese language support on MINI

With this release, we’ve introduced Japanese as an official language option for Original Prusa MINI and MINI+ printers, allowing a broader global audience to interact with the machine more intuitively.

Mapping screen from Prusa Connect

This release introduces support for multi-tool filament mapping screen from Prusa Connect. While this feature is still in development and thus not fully functional, users will notice incremental updates as we continue to integrate these tools.

Community Contributions

We would like to extend our gratitude to the Prusa community for their invaluable contributions to this release. The following improvements were made by community members:

• Enable DNS for SNTP Client: DNS support for the SNTP client has been enabled, and the default server is now set to prusa3d.pool.ntp.org (thanks to @thess via #3730).
• Quoted INI String Support: Support for quoted INI string values has been added (contributed by @nmschulte via #3158).
• Experimental Serial Printing Screen: A new experimental option has been added to disable the serial printing screen (contributed by @PinkPandaKatie via #4071).
• Trailing Zeroes Fix: Fixed an issue where trailing zeroes were incorrectly displayed in the footer (thanks to @puhitaku via #4129).
• German Translation Fix: The German translation has been improved (contributed by @foorschtbar via #4136).
• XL Debugging Improvements: Enhanced debugging features for the Original Prusa XL (thanks to @vintagepc via #3419).

We would also like to take this opportunity to thank the community for submitting crash dumps. These reports have been critical in helping us identify and resolve bugs, and we are pleased to note that crash reports have significantly decreased over the past two months.

Bug Fixes

Wi-Fi stability improvements

Several bugs related to Wi-Fi connectivity have been addressed, including crashes caused by high outgoing traffic. This should improve overall network stability during data-intensive tasks.

G-code transfer fixes

We’ve resolved issues causing BSODs at the end of G-code transfers with specific file sizes. Additionally, we’ve improved the process for cleaning up failed transfers to prevent clutter and reduce potential errors.

USB media prefetch

A media prefetch feature has been overhauled, addressing recurring USB errors by improved handling of data during the print process. This should result in fewer connectivity issues during printing.

Improved preview loading during file transfer

We've optimized the print preview during file transfer from Prusa Connect. Previously, the preview appeared only after 50% of the file was downloaded, even though the necessary data was available earlier. This fix improves polling frequency and task prioritization to ensure faster preview generation and quicker print start times.

MINI sensor update fix

The MINI previously failed to update sensor statuses correctly. This has now been fixed, ensuring that users receive accurate sensor data during operations.

Persistent compatibility mode

We have addressed an issue where the compatibility mode settings were not properly stored or restored after a power panic procedure was triggered.

Model adjustments

CoreXY model calculations

The CoreXY physics model has been revised to better align with the actual physical system, ensuring more accurate and consistent movement calculations.

Known Issues and Regressions

Wi-Fi throughput regression

We’ve identified a potential regression where Wi-Fi throughput may have decreased. We are actively working on a fix and will include it in an upcoming update.