Marlin 2.0.7.2, Ender 3 Pro, BTT SKR 1.4 Turbo with ABL using BLTouch v3.1

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This article describes another release for Marlin this version is 2.0.7.2 based on the release from 22nd October 2020 for use with the Ender 3 Pro and a custom hardware configuration: BigTreeTech SKR 1.4 board, TMC2209 drivers, BLTouch v3.1 (others supported check wiring).

Important information

There are newer versions of this article and Marlin configurations available:

Here are some highlights on key features enabled in this custom version of Marlin 2.0.7.2:

  • TMC2209 drivers with Stealth-chop & Hybrid threshold enabled on X, Y, Z axis.
  • BLTouch for ABL Bilinear.
    • Bed levelling is used in addition to a Z-stop switch.
    • Menu for levelling bed corners.
    • Restore bed levelling after G28.
    • Probes bed once at each point.
  • Movement on any axis is restricted until axis’s are homed.
  • Emergency stop interrupt commands supported
  • PID Tuning
  • Extruder fan after 50°C
  • Z Safe homing
  • Advanced pause and filament change
  • Classic Jerk or Junction Deviation (see note below)

Read more on changes/fixes in the official Marlin 2.0.7.2 change log and Marlin 2.0.7.1 change log.

It’s assumed that you have the following equipment:

  • BTT SKR 1.4 Board.
  • BLTouch v3.1 (other versions of the BLTouch will work but you will need to adjust settings related to it and check your wiring).
  • Ender 3 Pro or 3.

Preparation

PlatformIO Installation

I suggest VSCode as a quick method for compiling Marlin 2.0.x from source.

  1. Download VSCode and install.
  2. Open VSCode > Extension Manager > Search for and install the official PlatformIO IDE extension.

Firmware sources

Binary release

View 2.0.7.2 release

Building your own binary

I have made my Marlin configurations available for download they feature the same changes mentioned within this article; if you use my configuration you will need to review your Probe offsets & determine if your endstops requiring inversion:

To build your own variant from source; start by downloading the relevant Marlin releases used in this article from Marlin 2.0.7.2 branch:

Once you have downloaded the sources above you will need to extract them to an accessible location, use the following steps as a reference:

  1. Download and extract Marlin 2.0.7.2 sources
  2. Copy the 4 files to the Marlin directory contained within the extracted Marlin 2.0.7.2 sources.

Firmware configuration modifications

Next we will be modifying 2 specific files from the release to customise the firmware for to our requirements:

  • /Marlin/Configuration.h
  • /Marlin/Configuration_adv.h

Depending upon whether you used my configurations or the stock configurations will determine if you need to merge the changes required to support the new hardware:

  1. Compare file: /Marlin/Configuration.h with custom file: Configuration.h (BitBucket)
  2. Compare file: /Marlin/Configuration_adv.h with custom file: Configuration_adv.h (BitBucket)

Switching between Classic Jerk and Junction Deviation

In the configuration provided you can change between classic jerk and junction deviation by commenting out #CLASSIC_JERK (found on line 787 in Configuration.h).

//#define CLASSIC_JERK
#if ENABLED(CLASSIC_JERK)
  #define DEFAULT_XJERK 10.0
  #define DEFAULT_YJERK 10.0
  #define DEFAULT_ZJERK  0.3

  //#define TRAVEL_EXTRA_XYJERK 0.0     // Additional jerk allowance for all travel moves

  //#define LIMITED_JERK_EDITING        // Limit edit via M205 or LCD to DEFAULT_aJERK * 2
  #if ENABLED(LIMITED_JERK_EDITING)
    #define MAX_JERK_EDIT_VALUES { 20, 20, 0.6, 10 } // ...or, set your own edit limits
  #endif
#endif

#define DEFAULT_EJERK    5.0  // May be used by Linear Advance

/**
 * Junction Deviation Factor
 *
 * See:
 *   https://reprap.org/forum/read.php?1,739819
 *   https://blog.kyneticcnc.com/2018/10/computing-junction-deviation-for-marlin.html
 */
#if DISABLED(CLASSIC_JERK)
  #define JUNCTION_DEVIATION_MM 0.08  // (mm) Distance from real junction edge
  #define JD_HANDLE_SMALL_SEGMENTS    // Use curvature estimation instead of just the junction angle
                                      // for small segments (< 1mm) with large junction angles (> 135°).
#endif
Configuration.hView rawView file on GitLab

When using these device configurations you should take care to check the following are suited to your setup/configuration:

  • Probe offsets for X, Y, Z (important; see below).
  • Require Fade height?
  • PID tuning (recommended).
  • E-Step calibration.
  • Endstops may need inverting depending on your wiring see below.

Important note on Probe offsets

Keep in mind that in using this; you will likely need to adjust your X, Y, Z offset settings specific to your setup. The change is simple and the key settings to look for is NOZZLE_TO_PROBE_OFFSET if you wish to make the change in source. Once found, this branch of Marlin requires the offsets to be defined as an array: {x, y, z}.

The alternative is updating the probe offset values after the new firmware has been installed.

Updating Probe offset values manually using G-code M851

The following example shows the G-Code I would use to set the offset values after flashing a new firmware. You will need to adjust these offsets to accommodate your own requirements.

Set the Z offset for the BLTouch by sending G-code:

M851 Z-1.46

Set the X and Y distance (probe left front of nozzle) by sending G-code:

M851 X-46.00 Y-16.00

Save the setting to the EEPROM by sending G-code:

M500

Setting Fade Height manually via G-code M420

Set the Fade Height with G-Code:

M420 Z10

Determining if Endstops need to be inverted

Get all endstop states by sending G-Code:

M119

It will report something similar to:

Reporting endstop status
x_min: open
y_min: open
z_min: TRIGGERED
z_probe: open
filament: open

If an endstop is reporting triggered but is not actually triggered (by this I mean pushed) or is reporting open when the switch is pushed then you will need to invert the endstop. If was true initially set to false and vice-versa.

Below are two options for addressing this requirement.

Endstop inversion option 1

If you would prefer to change the inversion on a endstop or endstops in the configuration to compile yourself look for the following:

// Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
#define X_MIN_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define X_MAX_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define Z_MIN_PROBE_ENDSTOP_INVERTING true // Set to true to invert the logic of the probe.
Configuration.hView rawView file on GitLab

Endstop inversion option 2

Alternatively; if you wish avoid editing the configuration and utilise the binaries available on this blog; you could swap the placement of the two wires in the DuPont connector, carefully ejecting each wire with a pin/needle and repositioning them by swapping them around.

The mod could be made on either end of the cable plugged in to the endstop; cable closest to the endstop would likely be a easier option for most.