Replace M905 with unique code M900

Marlin/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/Marlin_main.cpp

 
 #if ENABLED(LIN_ADVANCE)
   /**
-   * M905: Set and/or Get advance K factor and WH/D ratio
+   * M900: Set and/or Get advance K factor and WH/D ratio
    *
    *  K<factor>                  Set advance K factor
    *  R<ratio>                   Set ratio directly (overrides WH/D)
    *  W<width> H<height> D<diam> Set ratio from WH/D
    */
-  inline void gcode_M905() {
+  inline void gcode_M900() {
     stepper.synchronize();
 
     const float newK = code_seen('K') ? code_value_float() : -1;
       #endif // DUAL_X_CARRIAGE
 
       #if ENABLED(LIN_ADVANCE)
-        case 905: // M905: Set advance K factor.
-          gcode_M905();
+        case 900: // M900: Set advance K factor.
+          gcode_M900();
           break;
       #endif
 

Marlin/configuration_store.cpp

  *  576  M906 E4   stepperE4 current                (uint16_t)
  *
  * LIN_ADVANCE:                                     8 bytes
- *  580  M905 K    extruder_advance_k               (float)
- *  584  M905 WHD  advance_ed_ratio                 (float)
+ *  580  M900 K    extruder_advance_k               (float)
+ *  584  M900 WHD  advance_ed_ratio                 (float)
  *
  *  588                                Minimum end-point
  * 1909 (588 + 36 + 9 + 288 + 988)     Maximum end-point
         SERIAL_ECHOLNPGM("Linear Advance:");
       }
       CONFIG_ECHO_START;
-      SERIAL_ECHOPAIR("  M905 K", planner.get_extruder_advance_k());
+      SERIAL_ECHOPAIR("  M900 K", planner.get_extruder_advance_k());
       SERIAL_ECHOLNPAIR(" R", planner.get_advance_ed_ratio());
     #endif
   }

Marlin/example_configurations/Cartesio/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/Felix/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/Hephestos/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/Hephestos_2/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/K8200/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/K8400/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/RigidBot/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/SCARA/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/TAZ4/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/TinyBoy2/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/WITBOX/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/delta/generic/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/delta/kossel_mini/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/delta/kossel_pro/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/delta/kossel_xl/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/makibox/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/tvrrug/Round2/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.

Marlin/example_configurations/wt150/Configuration_adv.h

    * to a fixed value. Note that using a fixed ratio will lead to wrong nozzle pressures
    * if the slicer is using variable widths or layer heights within one print!
    *
-   * This option sets the default E:D ratio at startup. Use `M905` to override this value.
+   * This option sets the default E:D ratio at startup. Use `M900` to override this value.
    *
-   * Example: `M905 W0.4 H0.2 D1.75`, where:
+   * Example: `M900 W0.4 H0.2 D1.75`, where:
    *   - W is the extrusion width in mm
    *   - H is the layer height in mm
    *   - D is the filament diameter in mm
    *
+   * Example: `M900 R0.0458` to set the ratio directly.
+   *
    * Set to 0 to auto-detect the ratio based on given Gcode G1 print moves.
    *
    * Slic3r (including Prusa Slic3r) produces Gcode compatible with the automatic mode.