Gcode Preprocessing

Page Sections:

• Supported Placeholders
  • !referenced_tools!
  • !colors!
  • !temperatures!
  • !purge_volumes!

Happy Hare now provides a moonraker gcode preprocesser that parses uploaded gcode files prior to storage and can insert useful metadata that can then be passed into your START_PRINT macro to provide useful functionality.

This support is added to Moonraker configuration during installation but can be added manually by inserting the following lines into your moonraker.conf file and restarting Moonraker. Setting enable_file_preprocessor: False will disable this functionality.

[mmu_server]
enable_file_preprocessor: True

The functionality is similar to the "placeholder" substitution that many slicers do. For example if you use {total_toolchanges} in PrusaSlicer, it will substitute this placeholder with the actual number of tool changes. When used in conjunction with a call to your START_PRINT macro you can pass parameters to use at print time. E.g. by defining your "start" G-Code as:

START_PRINT TOOL_CHANGES={total_toolchanges} ....

Your START_PRINT macro thus gets the number of tool changes passed as an integer parameter.

The Happy Hare pre-processor implements similar functionality but runs when the file is uploaded to Moonraker. To distinguish from Slicer added tokens, this pre-processor delimits placeholders with ! marks. Note that this does not duplicate all the Slicer placeholders but provides an extensible mechanism to implement anything missing in the slicer. At this time a single placeholder !referenced_tools! is implemented but this might grow over time.

Note

The {referenced_tools} placeholder has been submitted as a PR for PrusaSlicer but it has not yet been incorporated, so you can use !referenced_tools! instead!

Supported Placeholders

Placeholder: !referenced_tools!

This placeholder is substituted with a comma separated list of tools used in a print. If there are no toolchanges (non MMU print) it will be an empty string. E.g. 0,2,5,6 means that T0, T2, T5 and T6 are used in the print.

Why is this useful?
When combined with the MMU_CHECK_GATE TOOLS= functionality and placed in your START_PRINT macro it allows for up-front verification that all required tools are present before commencing the print!

To implement incorporate into your start g-code on your Slicer:

START_PRINT REFERENCED_TOOLS=!referenced_tools! INITIAL_TOOL={initial_tool} ...the other parameters...

Then in you print start macro add logic similar to:

[gcode_macro START_PRINT]
description: Called when starting print
gcode:
    {% set REFERENCED_TOOLS = params.REFERENCED_TOOLS|default("")|string %}
    {% set INITIAL_TOOL = params.INITIAL_TOOL|default(0)|int %}

    {% if REFERENCED_TOOLS == "!referenced_tools!" %}
        RESPOND MSG="Happy Hare gcode pre-processor is diabled"
        {% set REFERENCED_TOOLS = INITIAL_TOOL %}
    {% elif REFERENCED_TOOLS == "" %}
        RESPOND MSG="Happy Hare single color print"
        {% set REFERENCED_TOOLS = INITIAL_TOOL %}
    {% endif %}

    ; other logic..

    MMU_CHECK_GATE TOOLS={REFERENCED_TOOLS}

    ; other logic..

    MMU_CHANGE_TOOL STANDALONE=1 TOOL={INITIAL_TOOL}    # Optional: load initial tool

Note

• MMU_CHECK_GATE TOOLS= with empty string will be ignored by Happy Hare.
  
• Any tool that was loaded prior to calling MMU_CHECK_GATE will be automatically restored at the end of the checking procedure.
  
• In the gcode snippet above we also pass in the slicer placeholder {initial_tool} because single color prints have no tool changes and thus REFERENCED_TOOLS (which counts Tx commands) will be empty. This code will ensure that REFERENCED_TOOLS will always contain the initial tool.

Placeholder: !colors!

This placeholder is substituted with a comma separated list of extruder colors as defined in the slicer. This could be used to setup the filament colors in the MMU gate map. Although the colors defined in the slicer have nothing to do with the actual filaments loaded in the MMU it might be convenient (if not using spoolman) to transfer over the colors from the slicer gcode file, light LEDs on the MMU and perform a visual match on the whether the correct filaments are loaded

To implement incorporate into your start g-code on your Slicer:

START_PRINT COLORS=!colors! ...the other parameters...

Then in you print start macro add logic similar to:

[gcode_macro START_PRINT]
description: Called when starting print
gcode:
    {% set COLORS = params.COLORS|default("")|string %}
    {% set colors = COLORS.split(",") %}
    {% set ttg_map = printer.mmu.ttg_map %}

    {% for color in colors %}
        {% set tool = loop.index0 %}
        {% set gate = ttg_map[tool] %}                  # Make sure map to correct gate in case of TTG map
        MMU_GATE_MAP GATE={gate} COLOR={color}          # Register the filament color against correct gate in gate map
    {% endfor %}

To see the colors displayed you need to enable LED support and use the filament_color effect. E.g. to display both on exit led and the color of current filament on the status led:

MMU_LED EXIT_EFFECT=filament_color STATUS_EFFECT=filament_color

Note that this is used as an example only because the default recommended MMU_START_SETUP macro will store the slicer colors in the "slicer tool map" and the slicer defined colors can simply be displayed by setting the led effect to slicer_color :-) But using the above as a guide you can do other creative things with slicer defined colors.

Note

Filament colors are available in RGB float from to directly drive other leds by accessing the printer variables: printer.mmu.gate_color_rbg (filament colors in the gate map) and printer.mmu.slicer_color_rgb (filament colors defined by slicer). These contains a list of truples contains the 0-1.0 value for each of the R,G,B pixels. See led doc for more details.

Placeholder: !temperatures!

This placeholder is substituted with a comma separated list of filament temperatures as defined in the slicer.

Placeholder: !purge_volumes!

This placeholder is substituted with a comma separated list of NxN purge volumes (see Purging) used when changing from tool X to tool Y