[2.0] Fix Mixing Extruder mixing factors (#11861)

Marlin/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/default/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/AlephObjects/TAZ4/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/AliExpress/CL-260/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Anet/A2/Configuration.h

@@ -208,11 +208,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Anet/A2plus/Configuration.h

@@ -208,11 +208,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Anet/A6/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Anet/A8/Configuration.h

@@ -226,11 +226,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Azteeg/X5GT/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/BIBO/TouchX/cyclops/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/BIBO/TouchX/default/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/BQ/Hephestos/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/BQ/Hephestos_2/Configuration.h

@@ -233,11 +233,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/BQ/WITBOX/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Cartesio/Configuration.h

@@ -226,11 +226,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/CR-10/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/CR-10S/Configuration.h

@@ -229,11 +229,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/CR-10mini/Configuration.h

@@ -234,11 +234,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/CR-8/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/Ender-2/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/Ender-3/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Creality/Ender-4/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Einstart-S/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Felix/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Felix/DUAL/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/FolgerTech/i3-2020/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Formbot/T-Rex_2+/Configuration.h

@@ -215,11 +215,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Formbot/T_Rex_3/Configuration.h

@@ -220,11 +220,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Geeetech/GT2560/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Geeetech/I3_Pro_X-GT2560/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Geeetech/Prusa i3 Pro B/bltouch/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Geeetech/Prusa i3 Pro B/noprobe/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Geeetech/Prusa i3 Pro C/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Geeetech/Prusa i3 Pro W/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Infitary/i3-M508/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/JGAurora/A5/Configuration.h

@@ -230,11 +230,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/MakerParts/Configuration.h

@@ -245,11 +245,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Malyan/M150/Configuration.h

@@ -230,11 +230,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Malyan/M200/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Micromake/C1/basic/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Micromake/C1/enhanced/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Mks/Sbase/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/RepRapPro/Huxley/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/RepRapWorld/Megatronics/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/RigidBot/Configuration.h

@@ -228,11 +228,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/SCARA/Configuration.h

@@ -256,11 +256,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/STM32F10/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/STM32F4/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Sanguinololu/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/TheBorg/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/TinyBoy2/Configuration.h

@@ -247,11 +247,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Tronxy/X1/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Tronxy/X3A/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Tronxy/X5S/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Tronxy/XY100/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/UltiMachine/Archim2/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Velleman/K8200/Configuration.h

@@ -245,11 +245,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Velleman/K8400/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Velleman/K8400/Dual-head/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/Wanhao/Duplicator 6/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/adafruit/ST7565/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/Anycubic/Kossel/Configuration.h

@@ -221,11 +221,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/FLSUN/kossel/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/Hatchbox_Alpha/Configuration.h

@@ -230,11 +230,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/generic/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/kossel_mini/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/kossel_pro/Configuration.h

@@ -229,11 +229,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/delta/kossel_xl/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/gCreate/gMax1.5+/Configuration.h

@@ -230,11 +230,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/makibox/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/stm32f103ret6/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/tvrrug/Round2/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/config/examples/wt150/Configuration.h

@@ -225,11 +225,11 @@
 
 /**
  * "Mixing Extruder"
- *   - Adds a new code, M165, to set the current mix factors.
+ *   - Adds G-codes M163 and M164 to set and "commit" the current mix factors.
  *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
- *   - Optional support for Repetier Firmware M163, M164, and virtual extruder.
- *   - This implementation supports only a single extruder.
- *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
+ *   - Optional support for Repetier Firmware's 'M164 S<index>' supporting virtual tools.
+ *   - This implementation supports up to two mixing extruders.
+ *   - Enable DIRECT_MIXING_IN_G1 for M165 and mixing in G1 (from Pia Taubert's reference implementation).
  */
 //#define MIXING_EXTRUDER
 #if ENABLED(MIXING_EXTRUDER)

Marlin/src/feature/mixing.cpp

@@ -56,12 +56,12 @@ float mixing_factor[MIXING_STEPPERS]; // Reciprocal of mix proportion. 0.0 = off
 
 void normalize_mix() {
   float mix_total = 0.0;
-  for (uint8_t i = 0; i < MIXING_STEPPERS; i++) mix_total += mixing_factor[i]; // Ex: 1/4 + 1/8 + 1/8 = 1/2
+  for (uint8_t i = 0; i < MIXING_STEPPERS; i++) mix_total += mixing_factor[i];
   // Scale all values if they don't add up to ~1.0
   if (!NEAR(mix_total, 1.0)) {
     SERIAL_PROTOCOLLNPGM("Warning: Mix factors must add up to 1.0. Scaling.");
-    mix_total = RECIPROCAL(mix_total);
-    for (uint8_t i = 0; i < MIXING_STEPPERS; i++) mixing_factor[i] *= mix_total; // Ex: 1/4*2 + 1/8*2 + 1/8*2 = 1/2 + 1/4 + 1/4 = 1
+    const float inverse_sum = RECIPROCAL(mix_total);
+    for (uint8_t i = 0; i < MIXING_STEPPERS; i++) mixing_factor[i] *= inverse_sum;
   }
 }
 
@@ -70,14 +70,25 @@ void normalize_mix() {
   // The total "must" be 1.0 (but it will be normalized)
   // If no mix factors are given, the old mix is preserved
   void gcode_get_mix() {
-    const char mixing_codes[] = { 'A', 'B', 'C', 'D', 'H', 'I' };
+    const char mixing_codes[] = { 'A', 'B'
+      #if MIXING_STEPPERS > 2
+        , 'C'
+        #if MIXING_STEPPERS > 3
+          , 'D'
+          #if MIXING_STEPPERS > 4
+            , 'H'
+            #if MIXING_STEPPERS > 5
+              , 'I'
+            #endif // MIXING_STEPPERS > 5
+          #endif // MIXING_STEPPERS > 4
+        #endif // MIXING_STEPPERS > 3
+      #endif // MIXING_STEPPERS > 2
+    };
     byte mix_bits = 0;
     for (uint8_t i = 0; i < MIXING_STEPPERS; i++) {
       if (parser.seenval(mixing_codes[i])) {
         SBI(mix_bits, i);
-        float v = parser.value_float();
-        NOLESS(v, 0.0);
-        mixing_factor[i] = RECIPROCAL(v);
+        mixing_factor[i] = MAX(parser.value_float(), 0.0);
       }
     }
     // If any mixing factors were included, clear the rest

Marlin/src/gcode/feature/mixing/M163-M165.cpp

@@ -30,45 +30,40 @@
 /**
  * M163: Set a single mix factor for a mixing extruder
  *       This is called "weight" by some systems.
+ *       The 'P' values must sum to 1.0 or must be followed by M164 to normalize them.
  *
  *   S[index]   The channel index to set
  *   P[float]   The mix value
- *
  */
 void GcodeSuite::M163() {
   const int mix_index = parser.intval('S');
-  if (mix_index < MIXING_STEPPERS) {
-    float mix_value = parser.floatval('P');
-    NOLESS(mix_value, 0.0);
-    mixing_factor[mix_index] = RECIPROCAL(mix_value);
-  }
+  if (mix_index < MIXING_STEPPERS)
+    mixing_factor[mix_index] = MAX(parser.floatval('P'), 0.0);
 }
 
-#if MIXING_VIRTUAL_TOOLS > 1
-
-  /**
-   * M164: Store the current mix factors as a virtual tool.
-   *
-   *   S[index]   The virtual tool to store
-   *
-   */
-  void GcodeSuite::M164() {
-    const int tool_index = parser.intval('S');
-    if (tool_index < MIXING_VIRTUAL_TOOLS) {
-      normalize_mix();
+/**
+ * M164: Normalize and commit the mix.
+ *       If 'S' is given store as a virtual tool. (Requires MIXING_VIRTUAL_TOOLS > 1)
+ *
+ *   S[index]   The virtual tool to store
+ */
+void GcodeSuite::M164() {
+  normalize_mix();
+  #if MIXING_VIRTUAL_TOOLS > 1
+    const int tool_index = parser.intval('S', -1);
+    if (WITHIN(tool_index, 0, MIXING_VIRTUAL_TOOLS - 1)) {
       for (uint8_t i = 0; i < MIXING_STEPPERS; i++)
         mixing_virtual_tool_mix[tool_index][i] = mixing_factor[i];
     }
-  }
-
-#endif // MIXING_VIRTUAL_TOOLS > 1
+  #endif
+}
 
 #if ENABLED(DIRECT_MIXING_IN_G1)
 
   /**
    * M165: Set multiple mix factors for a mixing extruder.
    *       Factors that are left out will be set to 0.
-   *       All factors together must add up to 1.0.
+   *       All factors should sum to 1.0, but they will be normalized regardless.
    *
    *   A[factor] Mix factor for extruder stepper 1
    *   B[factor] Mix factor for extruder stepper 2
@@ -76,7 +71,6 @@ void GcodeSuite::M163() {
    *   D[factor] Mix factor for extruder stepper 4
    *   H[factor] Mix factor for extruder stepper 5
    *   I[factor] Mix factor for extruder stepper 6
-   *
    */
   void GcodeSuite::M165() { gcode_get_mix(); }
 

Marlin/src/gcode/gcode.h

@@ -145,8 +145,8 @@
  * M150 - Set Status LED Color as R<red> U<green> B<blue> P<bright>. Values 0-255. (Requires BLINKM, RGB_LED, RGBW_LED, NEOPIXEL_LED, or PCA9632).
  * M155 - Auto-report temperatures with interval of S<seconds>. (Requires AUTO_REPORT_TEMPERATURES)
  * M163 - Set a single proportion for a mixing extruder. (Requires MIXING_EXTRUDER)
- * M164 - Save the mix as a virtual extruder. (Requires MIXING_EXTRUDER and MIXING_VIRTUAL_TOOLS)
- * M165 - Set the proportions for a mixing extruder. Use parameters ABCDHI to set the mixing factors. (Requires MIXING_EXTRUDER)
+ * M164 - Commit the mix (Req. MIXING_EXTRUDER) and optionally save as a virtual tool (Req. MIXING_VIRTUAL_TOOLS > 1)
+ * M165 - Set the mix for a mixing extruder wuth parameters ABCDHI. (Requires MIXING_EXTRUDER and DIRECT_MIXING_IN_G1)
  * M190 - Sxxx Wait for bed current temp to reach target temp. ** Waits only when heating! **
  *        Rxxx Wait for bed current temp to reach target temp. ** Waits for heating or cooling. **
  * M200 - Set filament diameter, D<diameter>, setting E axis units to cubic. (Use S0 to revert to linear units.)