Add support for Průša MK2 Multiplexer

Marlin/Conditionals_LCD.h

 
   #define HAS_DEBUG_MENU ENABLED(LCD_PROGRESS_BAR_TEST)
 
+  // MK2 Multiplexer forces SINGLENOZZLE to be enabled
+  #if ENABLED(MK2_MULTIPLEXER)
+    #define SINGLENOZZLE
+  #endif
+
   /**
    * Extruders have some combination of stepper motors and hotends
    * so we separate these concepts into the defines:
    *  EXTRUDERS    - Number of Selectable Tools
    *  HOTENDS      - Number of hotends, whether connected or separate
    *  E_STEPPERS   - Number of actual E stepper motors
+   *  E_MANUAL     - Number of E steppers for LCD move options
    *  TOOL_E_INDEX - Index to use when getting/setting the tool state
    *
    */

Marlin/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/Marlin_main.cpp

 
 #endif // ADVANCED_PAUSE_FEATURE
 
+#if ENABLED(MK2_MULTIPLEXER)
+
+  inline void select_multiplexed_stepper(const uint8_t e) {
+    stepper.synchronize();
+    disable_e_steppers();
+    WRITE(E_MUX0_PIN, TEST(e, 0) ? HIGH : LOW);
+    WRITE(E_MUX1_PIN, TEST(e, 1) ? HIGH : LOW);
+    WRITE(E_MUX2_PIN, TEST(e, 2) ? HIGH : LOW);
+    safe_delay(100);
+  }
+
+  /**
+   * M702: Unload all extruders
+   */
+  inline void gcode_M702() {
+    for (uint8_t s = 0; s < E_STEPPERS; s++) {
+      select_multiplexed_stepper(e);
+      // TODO: standard unload filament function
+      // MK2 firmware behavior:
+      //  - Make sure temperature is high enough
+      //  - Raise Z to at least 15 to make room
+      //  - Extrude 1cm of filament in 1 second
+      //  - Under 230C quickly purge ~12mm, over 230C purge ~10mm
+      //  - Change E max feedrate to 80, eject the filament from the tube. Sync.
+      //  - Restore E max feedrate to 50
+    }
+    // Go back to the last active extruder
+    select_multiplexed_stepper(active_extruder);
+    disable_e_steppers();
+  }
+
+#endif // MK2_MULTIPLEXER
+
 #if ENABLED(DUAL_X_CARRIAGE)
 
   /**
       UNUSED(fr_mm_s);
       UNUSED(no_move);
 
-      // Set the new active extruder
-      active_extruder = tmp_extruder;
+      #if ENABLED(SWITCHING_EXTRUDER) && !DONT_SWITCH
+
+        stepper.synchronize();
+        move_extruder_servo(tmp_extruder);
+
+      #elif ENABLED(MK2_MULTIPLEXER)
+
+        if (tmp_extruder >= E_STEPPERS)
+          return invalid_extruder_error(tmp_extruder);
+
+        select_multiplexed_stepper(tmp_extruder);
+
+      #endif
 
     #endif // HOTENDS <= 1
 
-    #if ENABLED(SWITCHING_EXTRUDER) && !DONT_SWITCH
-      move_extruder_servo(active_extruder);
-    #endif
+    active_extruder = tmp_extruder;
 
     SERIAL_ECHO_START();
     SERIAL_ECHOLNPAIR(MSG_ACTIVE_EXTRUDER, (int)active_extruder);
           break;
       #endif // DUAL_X_CARRIAGE
 
+      #if ENABLED(MK2_MULTIPLEXER)
+        case 702: // M702: Unload all extruders
+          gcode_M702();
+          break;
+      #endif
+
       #if ENABLED(LIN_ADVANCE)
         case 900: // M900: Set advance K factor.
           gcode_M900();
     #endif
   #endif
 
+  #if ENABLED(MK2_MULTIPLEXER)
+    SET_OUTPUT(E_MUX0_PIN);
+    SET_OUTPUT(E_MUX1_PIN);
+    SET_OUTPUT(E_MUX2_PIN);
+  #endif
+
   lcd_init();
   #if ENABLED(SHOW_BOOTSCREEN)
     #if ENABLED(DOGLCD)

Marlin/SanityCheck.h

     #error "EXTRUDERS must be 1 with HEATERS_PARALLEL."
   #endif
 
+#elif ENABLED(MK2_MULTIPLEXER)
+  #error "MK2_MULTIPLEXER requires 2 or more EXTRUDERS."
 #elif ENABLED(SINGLENOZZLE)
   #error "SINGLENOZZLE requires 2 or more EXTRUDERS."
 #endif
 
 /**
+ * Sanity checking for the Průša MK2 Multiplexer
+ */
+#ifdef SNMM
+  #error "SNMM is now MK2_MULTIPLEXER. Please update your configuration."
+#elif ENABLED(MK2_MULTIPLEXER) && DISABLED(ADVANCED_PAUSE_FEATURE)
+  #error "ADVANCED_PAUSE_FEATURE is required with MK2_MULTIPLEXER."
+#endif
+
+/**
  * A Dual Nozzle carriage with switching servo
  */
 #if ENABLED(SWITCHING_NOZZLE)

Marlin/example_configurations/Anet/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/CL-260/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/Cartesio/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/Felix/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/Felix/DUAL/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/FolgerTech-i3-2020/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/Hephestos/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/Hephestos_2/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/K8200/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/K8400/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/K8400/Dual-head/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/M150/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/RigidBot/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/SCARA/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/TAZ4/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/TinyBoy2/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/WITBOX/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/adafruit/ST7565/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

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

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

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

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/delta/generic/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/delta/kossel_mini/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/delta/kossel_pro/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/delta/kossel_xl/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/gCreate_gMax1.5+/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/makibox/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/tvrrug/Round2/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/example_configurations/wt150/Configuration.h

 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
+/**
+ * Průša MK2 Single Nozzle Multi-Material Multiplexer, and variants.
+ *
+ * This device allows one stepper driver on a control board to drive
+ * two to eight stepper motors, one at a time, in a manner suitable
+ * for extruders.
+ *
+ * This option only allows the multiplexer to switch on tool-change.
+ * Additional options to configure custom E moves are pending.
+ */
+//#define MK2_MULTIPLEXER
+#if ENABLED(MK2_MULTIPLEXER)
+  // Override the default DIO selector pins here, if needed.
+  // Some pins files may provide defaults for these pins.
+  //#define E_MUX0_PIN 40  // Always Required
+  //#define E_MUX1_PIN 42  // Needed for 3 to 8 steppers
+  //#define E_MUX2_PIN 44  // Needed for 5 to 8 steppers
+#endif
+
 // A dual extruder that uses a single stepper motor
 //#define SWITCHING_EXTRUDER
 #if ENABLED(SWITCHING_EXTRUDER)

Marlin/pins_MINIRAMBO.h

 #define CASE_LIGHT_PIN      9
 
 //
+// M3/M4/M5 - Spindle/Laser Control
+//
+// use P1 connector for spindle pins
+#define SPINDLE_LASER_PWM_PIN     9  // MUST BE HARDWARE PWM
+#define SPINDLE_LASER_ENABLE_PIN 18  // Pin should have a pullup!
+#define SPINDLE_DIR_PIN          19
+
+//
+// Průša i3 MK2 Multiplexer Support
+//
+#define E_MUX0_PIN         17
+#define E_MUX1_PIN         16
+#define E_MUX2_PIN         78 // 84 in MK2 Firmware, with BEEPER as 78
+
+//
 // LCD / Controller
 //
 #if ENABLED(ULTRA_LCD)
 
   #endif // NEWPANEL
 #endif // ULTRA_LCD
-
-//
-// M3/M4/M5 - Spindle/Laser Control
-//
-
-// use P1 connector for spindle pins
-#define SPINDLE_LASER_PWM_PIN     9  // MUST BE HARDWARE PWM
-#define SPINDLE_LASER_ENABLE_PIN 18  // Pin should have a pullup!
-#define SPINDLE_DIR_PIN          19

Marlin/pins_RAMBO.h

 #endif
 
 //
+// M3/M4/M5 - Spindle/Laser Control
+//
+#define SPINDLE_LASER_PWM_PIN    45  // MUST BE HARDWARE PWM
+#define SPINDLE_LASER_ENABLE_PIN 31  // Pin should have a pullup!
+#define SPINDLE_DIR_PIN          32
+
+//
+// Průša i3 MK2 Multiplexer Support
+//
+#define E_MUX0_PIN         17
+#define E_MUX1_PIN         16
+#define E_MUX2_PIN         84 // 84 in MK2 Firmware
+
+//
 // LCD / Controller
 //
 #if ENABLED(ULTRA_LCD)
   #endif // !NEWPANEL
 
 #endif // ULTRA_LCD
-
-//
-// M3/M4/M5 - Spindle/Laser Control
-//
-#define SPINDLE_LASER_PWM_PIN    45  // MUST BE HARDWARE PWM
-#define SPINDLE_LASER_ENABLE_PIN 31  // Pin should have a pullup!
-#define SPINDLE_DIR_PIN          32

Marlin/pins_RAMPS.h

 #endif
 
 //
+// M3/M4/M5 - Spindle/Laser Control
+//
+#if ENABLED(SPINDLE_LASER_ENABLE) && !PIN_EXISTS(SPINDLE_LASER_ENABLE)
+  #if !defined(NUM_SERVOS) || NUM_SERVOS == 0 // try to use servo connector first
+    #define SPINDLE_LASER_ENABLE_PIN  4  // Pin should have a pullup/pulldown!
+    #define SPINDLE_LASER_PWM_PIN     6  // MUST BE HARDWARE PWM
+    #define SPINDLE_DIR_PIN           5
+  #elif !(ENABLED(ULTRA_LCD) && ENABLED(NEWPANEL) \
+      && (ENABLED(PANEL_ONE) || ENABLED(VIKI2) || ENABLED(miniVIKI) || ENABLED(MINIPANEL) || ENABLED(REPRAPWORLD_KEYPAD)))  // try to use AUX 2
+    #define SPINDLE_LASER_ENABLE_PIN 40  // Pin should have a pullup/pulldown!
+    #define SPINDLE_LASER_PWM_PIN    44  // MUST BE HARDWARE PWM
+    #define SPINDLE_DIR_PIN          65
+  #endif
+#endif
+
+//
+// Průša i3 MK2 Multiplexer Support
+//
+#define E_MUX0_PIN         40   // Z_CS_PIN
+#define E_MUX1_PIN         42   // E0_CS_PIN
+#define E_MUX2_PIN         44   // E1_CS_PIN
+
+//
 // LCD / Controller
 //
 #if ENABLED(ULTRA_LCD)
   #endif // NEWPANEL
 
 #endif // ULTRA_LCD
-
-//
-// M3/M4/M5 - Spindle/Laser Control
-//
-#if ENABLED(SPINDLE_LASER_ENABLE) && !PIN_EXISTS(SPINDLE_LASER_ENABLE)
-  #if !defined(NUM_SERVOS) || NUM_SERVOS == 0 // try to use servo connector first
-    #define SPINDLE_LASER_ENABLE_PIN  4  // Pin should have a pullup/pulldown!
-    #define SPINDLE_LASER_PWM_PIN     6  // MUST BE HARDWARE PWM
-    #define SPINDLE_DIR_PIN           5
-  #elif !(ENABLED(ULTRA_LCD) && ENABLED(NEWPANEL) \
-      && (ENABLED(PANEL_ONE) || ENABLED(VIKI2) || ENABLED(miniVIKI) || ENABLED(MINIPANEL) || ENABLED(REPRAPWORLD_KEYPAD)))  // try to use AUX 2
-    #define SPINDLE_LASER_ENABLE_PIN 40  // Pin should have a pullup/pulldown!
-    #define SPINDLE_LASER_PWM_PIN    44  // MUST BE HARDWARE PWM
-    #define SPINDLE_DIR_PIN          65
-  #endif
-#endif

Marlin/stepper.cpp

 
     nextAdvanceISR = eISR_Rate;
 
-    #define SET_E_STEP_DIR(INDEX) \
-      if (e_steps[INDEX]) E## INDEX ##_DIR_WRITE(e_steps[INDEX] < 0 ? INVERT_E## INDEX ##_DIR : !INVERT_E## INDEX ##_DIR)
+    #if ENABLED(MK2_MULTIPLEXER)
+      // Even-numbered steppers are reversed
+      #define SET_E_STEP_DIR(INDEX) \
+        if (e_steps[INDEX]) E## INDEX ##_DIR_WRITE(e_steps[INDEX] < 0 ? !INVERT_E## INDEX ##_DIR ^ TEST(INDEX, 0) : INVERT_E## INDEX ##_DIR ^ TEST(INDEX, 0))
+    #else
+      #define SET_E_STEP_DIR(INDEX) \
+        if (e_steps[INDEX]) E## INDEX ##_DIR_WRITE(e_steps[INDEX] < 0 ? INVERT_E## INDEX ##_DIR : !INVERT_E## INDEX ##_DIR)
+    #endif
 
     #define START_E_PULSE(INDEX) \
       if (e_steps[INDEX]) E## INDEX ##_STEP_WRITE(!INVERT_E_STEP_PIN)

Marlin/stepper_indirection.h

   #endif
 #else
   #define E_STEP_WRITE(v) E0_STEP_WRITE(v)
-  #define NORM_E_DIR() E0_DIR_WRITE(!INVERT_E0_DIR)
-  #define REV_E_DIR() E0_DIR_WRITE(INVERT_E0_DIR)
+  #if ENABLED(MK2_MULTIPLEXER)
+    // Even-numbered steppers are reversed
+    #define NORM_E_DIR() E0_DIR_WRITE(TEST(current_block->active_extruder, 0) ? !INVERT_E0_DIR: INVERT_E0_DIR)
+    #define REV_E_DIR() E0_DIR_WRITE(TEST(current_block->active_extruder, 0) ? INVERT_E0_DIR: !INVERT_E0_DIR)
+  #else
+    #define NORM_E_DIR() E0_DIR_WRITE(!INVERT_E0_DIR)
+    #define REV_E_DIR() E0_DIR_WRITE(INVERT_E0_DIR)
+  #endif
 #endif
 
 #endif // STEPPER_INDIRECTION_H