Firmware 3.9.0-BETA for Original Prusa i3 MK3S & MK3  

Firmware 3.9.0-BETA for Original Prusa i3 MK3S & MK3

Hi guys,

this a new early stage of the upcoming firmware version 3.9.0. This version is dedicated to experienced users.

Summary:

• Linear Advance 1.5
• Screen brightness adjustment
• Filament sensor status detection
• New G-codes sorting (last modified)
• MK3 Toggle and Translations
• MMU2S selector blade activated
• Show current Z offset in reset dialogue before first layer calibration
• Independent belt test
• Unknown Z position
• Other changes
• Fixed bugs
• Known issues
• GitHub templates

WARNING: In this release, the power panic feature is not working properly with the Original Prusa i3 MK3S. If you are experiencing frequent power surges, please consider waiting for the next release.

A detailed description

This firmware release is focused mainly on pull requests from the community. Since there are many changes, we have decided to release the firmware in the BETA version. Note that at this stage it is not recommended to use the firmware on a production printer!

We would like to thank everyone, who participated in this release!

New Features

Linear Advance 1.5

#1909
One of the biggest contributions from the community is the support for Linear Advance 1.5, which is also backward compatible with the previous version. In case you have a G-code with Linear Advance 1.0, the printer will analyze the code and convert the values.

This graph is showing the function used for converting LA 1.0 and 1.5

Screen brightness adjustment (MK3/MK3S only)

Starting this release the printer is capable of adjusting the brightness of the screen, which is convenient if the printer is used in a darker environment. The user can adjust the following parameters:

Screen Backlight ON

Screen Backlight OFF

In the menu head to Settings -> Brightness

Note that this feature is available for printers manufactured in the second half of 2019. In case you want to replace your screen, which doesn't support it, please head to the e-shop and open the spare parts section.

Filament sensor status detection

This is feature is still in development and the goal is a better recognition of the filament sensor status. The printer is continuously measuring the voltage (Support > Voltages) and based on the value it recognizes three states:

• Inserted filament: approx. 0.3 V - 0.5 V
• No filament: approx. 4.2 V - 4.6 V
• Disconnected sensor: approx. 4.8 V - 5.0 V

The sensor has to be at least version rev0.4 (red PCB).

New G-codes sorting (last modified)

Until now the G-codes on the SD card were sorted based on the time when each file was created and the system was ignoring any modification to it. Starting with 3.9.0-beta the files are sorted properly according to the last modification.

MK3 Toggle and Translations

The code responsible for displaying the toggle menus was rewritten in order to enable faster switching and lower the requirements on the CPU. Toggle menus were previously hardwired into the firmware, this is now changed to enable easier translations.

MMU2S selector blade activated

Part of the MMU2S unit is a selector equipped with a blade, which if needed will cut the tip of the filament unloaded from the extruder. Until now the cutting function wasn't enabled.

To start using this function, make sure you have:

• Firmware 1.0.6 installed in the MMU2S unit
• Firmware 3.9.0-beta installed in the MK3S/MK2.5S

The printed parts for the selector were updated to provide a better grip of the blade and will be available for download soon.

Show current Z offset in reset dialog before first layer calibration

In the case of rerunning the First Layer Calibration, the printer first checks if the value of Live Adjust Z is stored in the EEPROM. Before the process is started, the user is asked to confirm, whether the calibration should start from the current value of the Live Adjust Z or reset this value to zero (factory defaults).

Independent belt test

#1060 #1937
The belt test is evaluating if proper tension in the belts is achieved and until now the status was refreshed only after running the self-test. Based on the feedback from the community it is now as a standalone test available at all times. To run it, go to the Menu->Support->Belt status.

Unknown Z

In a situation when the printer doesn't know the exact Z-axis position (e.g. after the power on) a question mark is displayed on the screen next to the Z coordinate.

Language dictionary size increased

The original design of the memory blocks in the EEPROM expected files smaller than 64 KB. However, while increasing the number of functions and respective text strings, the size of some language dictionaries required a bigger space allocation. After successfully refactoring this part of the code, this limit is no longer present.

Other changes

Sheet's name displayed on the status screen

#2146 #2093
The name of the currently selected steel sheet is now displayed on the home screen for easier orientation.

Enable print fan while to speed up “waiting for a cooldown” procedure

#1704
While waiting for a hotend cooldown, the printer activates the print fan in order to speed up the cooling phase.

Safer moves in Z-axis, if the position is unknown

#1768
In a situation when the printer doesn't know the exact Z-axis position (e.g. after the power on) a stall guard is activated to stop the movement immediately if the obstacle (heatbed) is detected.

M350 for all axes

#2057
The G-code M350 (micro-stepping) is now implemented for all axis, previously only for the extruder.

Bug fixes

Heater running and extruder not parked at print's end

In some scenarios at the end of the print, the heater was still running and the extruder wasn't parked at the correct location.

F.I.N.D.A. sensor always triggered

The F.I.N.D.A. sensor on some MMU2S units was always triggered, even if no filament was present.

Infinite Loop

G-code M601 was in specific scenarios causing an endless loop.

Fixed planner for OctoprintMMU2S power panic improved

Fixed planner for Octoprint MMU2S after a power panic, which caused incorrect reconnection to the printed object.

Known Issues

Power panic

Power panic - as noted in the beginning the power panic function isn't working in this release.

Filament sensor for MK3

The optical sensor isn't detecting the filament correctly at all times.

Linear Advance e-jerk value

The conversion function between LA 1.5 and 1.0 doesn't refresh e-jerk value. As a result, the print might be up to 30 % slower.

Filament runout

The filament runout for MMU2S doesn't work properly.

Stop print

Stop print during print with MMU2S causes a filament runout.

GitHub templates

We have improved the procedure while creating an issue on the GitHub, the page is now equipped with several templates to address all possible issues.

• BUG
• ENHANCEMENT
• FEATURE REQUEST
• QUESTIONS

While starting a new issue please take your time, select and fill in the most appropriate one. It will speed up the entire process.

---

Supported printers:

• Original Prusa i3 MK3S MMU2S
• Original Prusa i3 MK3S
• Original Prusa i3 MK3
• Original Prusa i3 MK2.5S MMU2S
• Original Prusa i3 MK2.5S
• Original Prusa i3 MK2.5

Download link:

https://github.com/prusa3d/Prusa-Firmware/releases/tag/v3.9.0-beta

Note that MK3S, MK3, MK2.5S and MK2.5 are different printers! Each has its own firmware file!!!

Firmware flashing guide:

https://manual.prusa3d.com/Guide/Upgrading+the+firmware/66

Please report any bug here:

https://github.com/prusa3d/Prusa-Firmware/issues

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