Patch LIN_ADVANCE for style and forward-compatibility

Marlin/Configuration_adv.h

   #define D_FILAMENT 2.85
 #endif
 
+// Implementation of a linear pressure control
+// Assumption: advance = k * (delta velocity)
+// K=0 means advance disabled. A good value for a gregs wade extruder will be around K=75
+//#define LIN_ADVANCE
+
+#if ENABLED(LIN_ADVANCE)
+  #define LIN_ADVANCE_K 75
+#endif
+
 // @section leveling
 
 // Default mesh area is an area with an inset margin on the print area.
   #define MESH_MAX_Y (Y_MAX_POS - (MESH_INSET))
 #endif
 
-//Implementation of a linear pressure control
-//Assumption: advance = k * (delta velocity)
-//K=0 means advance disabled. A good value for a gregs wade extruder will be around K=75
-#define LIN_ADVANCE
-
-#if ENABLED(LIN_ADVANCE)
-  #define LIN_K 75
-#endif
-
 // @section extras
 
 // Arc interpretation settings:

Marlin/Marlin_main.cpp

 #endif // DUAL_X_CARRIAGE
 
 #if ENABLED(LIN_ADVANCE)
-/**
- * M905: Set advance factor
- */
-inline void gcode_M905() {
-  stepper.synchronize();
-  stepper.advance_M905();
-}
+  /**
+   * M905: Set advance factor
+   */
+  inline void gcode_M905() {
+    stepper.synchronize();
+    stepper.advance_M905();
+  }
 #endif
 
 /**

Marlin/SanityCheck.h

 #endif // AUTO_BED_LEVELING_FEATURE
 
 /**
+ * Advance Extrusion
+ */
+#if ENABLED(ADVANCE) && ENABLED(LIN_ADVANCE)
+  #error You can enable ADVANCE or LIN_ADVANCE, but not both.
+#endif
+
+/**
  * Filament Width Sensor
  */
 #if ENABLED(FILAMENT_WIDTH_SENSOR) && !HAS_FILAMENT_WIDTH_SENSOR
   #error "FILAMENT_WIDTH_SENSOR requires a FILWIDTH_PIN to be defined."
 #endif
 
-
 /**
  * ULTIPANEL encoder
  */

Marlin/planner.cpp

   // the maximum junction speed and may always be ignored for any speed reduction checks.
   block->nominal_length_flag = (block->nominal_speed <= v_allowable);
   block->recalculate_flag = true; // Always calculate trapezoid for new block
-  
-  #ifdef LIN_ADVANCE
-    //bse = allsteps: A problem occures if there is a very tiny move before a retract.
-    //In this case, the retract and the move will be executed together. This leads to an enormus amount advance steps due to a hughe e_acceleration.
-    //The math is correct, but you don't want a retract move done with advance! This situation has to be filtered out.
-    if ((!bse || (!bsx && !bsy && !bsz)) || (stepper.get_advance_k() == 0) || (bse == allsteps)) {
+
+  // Update previous path unit_vector and nominal speed
+  for (int i = 0; i < NUM_AXIS; i++) previous_speed[i] = current_speed[i];
+  previous_nominal_speed = block->nominal_speed;
+
+  #if ENABLED(LIN_ADVANCE)
+
+    // bse == allsteps: A problem occurs when there's a very tiny move before a retract.
+    // In this case, the retract and the move will be executed together.
+    // This leads to an enormous number of advance steps due to a huge e_acceleration.
+    // The math is correct, but you don't want a retract move done with advance!
+    // So this situation is filtered out here.
+    if (!bse || (!bsx && !bsy && !bsz) || stepper.get_advance_k() == 0 || bse == allsteps) {
       block->use_advance_lead = false;
-    } else {
+    }
+    else {
       block->use_advance_lead = true;
       block->e_speed_multiplier8 = (block->steps[E_AXIS] << 8) / block->step_event_count;
     }
-  #endif
 
-  // Update previous path unit_vector and nominal speed
-  for (int i = 0; i < NUM_AXIS; i++) previous_speed[i] = current_speed[i];
-  previous_nominal_speed = block->nominal_speed;
+  #elif ENABLED(ADVANCE)
 
-  #if ENABLED(ADVANCE)
     // Calculate advance rate
     if (!bse || (!bsx && !bsy && !bsz)) {
       block->advance_rate = 0;
      SERIAL_ECHOPGM("advance rate :");
      SERIAL_ECHOLN(block->advance_rate/256.0);
      */
-  #endif // ADVANCE
+
+  #endif // ADVANCE or LIN_ADVANCE
 
   calculate_trapezoid_for_block(block, block->entry_speed / block->nominal_speed, safe_speed / block->nominal_speed);
 

Marlin/planner.h

 
   unsigned char direction_bits;             // The direction bit set for this block (refers to *_DIRECTION_BIT in config.h)
 
-  #if ENABLED(ADVANCE)
+  // Advance extrusion
+  #if ENABLED(LIN_ADVANCE)
+    bool use_advance_lead;
+    int e_speed_multiplier8; // Factorised by 2^8 to avoid float
+  #elif ENABLED(ADVANCE)
     long advance_rate;
     volatile long initial_advance;
     volatile long final_advance;
     float advance;
   #endif
-  #ifdef LIN_ADVANCE
-    bool use_advance_lead;
-    int e_speed_multiplier8; //factorised by 2^8 to avoid float
-  #endif
 
   // Fields used by the motion planner to manage acceleration
   float nominal_speed,                               // The nominal speed for this block in mm/sec

Marlin/stepper.cpp

 
 volatile unsigned long Stepper::step_events_completed = 0; // The number of step events executed in the current block
 
-#if ENABLED(ADVANCE)
+#if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+
   unsigned char Stepper::old_OCR0A;
-  long  Stepper::final_advance = 0,
-        Stepper::old_advance = 0,
-        Stepper::e_steps[EXTRUDERS],
-        Stepper::advance_rate,
-        Stepper::advance;
+  volatile unsigned char Stepper::eISR_Rate = 200; // Keep the ISR at a low rate until needed
+
+  #if ENABLED(LIN_ADVANCE)
+    volatile int Stepper::e_steps[EXTRUDERS];
+    int Stepper::extruder_advance_k = LIN_ADVANCE_K,
+        Stepper::final_estep_rate,
+        Stepper::current_estep_rate[EXTRUDERS],
+        Stepper::current_adv_steps[EXTRUDERS];
+  #else
+    long  Stepper::e_steps[EXTRUDERS],
+          Stepper::final_advance = 0,
+          Stepper::old_advance = 0,
+          Stepper::advance_rate,
+          Stepper::advance;
+  #endif
 #endif
 
 long Stepper::acceleration_time, Stepper::deceleration_time;
         customizedSerial.checkRx(); // Check for serial chars.
       #endif
 
-      #if ENABLED(ADVANCE)
-        counter_E += current_block->steps[E_AXIS];
-        if (counter_E > 0) {
-          counter_E -= current_block->step_event_count;
-          e_steps[current_block->active_extruder] += motor_direction(E_AXIS) ? -1 : 1;
-        }
-      #endif //ADVANCE
-      
       #if ENABLED(LIN_ADVANCE)
+
         counter_E += current_block->steps[E_AXIS];
         if (counter_E > 0) {
           counter_E -= current_block->step_event_count;
-          count_position[_AXIS(E)] += count_direction[_AXIS(E)];
+          count_position[E_AXIS] += count_direction[E_AXIS];
           e_steps[current_block->active_extruder] += motor_direction(E_AXIS) ? -1 : 1;
         }
-        
-        if (current_block->use_advance_lead){
+
+        if (current_block->use_advance_lead) {
           int delta_adv_steps; //Maybe a char would be enough?
           delta_adv_steps = (((long)extruder_advance_k * current_estep_rate[current_block->active_extruder]) >> 9) - current_adv_steps[current_block->active_extruder];
           e_steps[current_block->active_extruder] += delta_adv_steps;
           current_adv_steps[current_block->active_extruder] += delta_adv_steps;
         }
-      #endif //LIN_ADVANCE
 
+      #elif ENABLED(ADVANCE)
+
+        counter_E += current_block->steps[E_AXIS];
+        if (counter_E > 0) {
+          counter_E -= current_block->step_event_count;
+          e_steps[current_block->active_extruder] += motor_direction(E_AXIS) ? -1 : 1;
+        }
+
+      #endif // ADVANCE or LIN_ADVANCE
+      
       #define _COUNTER(AXIS) counter_## AXIS
       #define _APPLY_STEP(AXIS) AXIS ##_APPLY_STEP
       #define _INVERT_STEP_PIN(AXIS) INVERT_## AXIS ##_STEP_PIN
       STEP_ADD(X);
       STEP_ADD(Y);
       STEP_ADD(Z);
-      #if (DISABLED(ADVANCE) && DISABLED(LIN_ADVANCE))
+      #if DISABLED(ADVANCE) && DISABLED(LIN_ADVANCE)
         STEP_ADD(E);
       #endif
 
       STEP_IF_COUNTER(X);
       STEP_IF_COUNTER(Y);
       STEP_IF_COUNTER(Z);
-      #if (DISABLED(ADVANCE) && DISABLED(LIN_ADVANCE))
+      #if DISABLED(ADVANCE) && DISABLED(LIN_ADVANCE)
         STEP_IF_COUNTER(E);
       #endif
 
       acceleration_time += timer;
       
       #if ENABLED(LIN_ADVANCE)
-        if (current_block->use_advance_lead){
+
+        if (current_block->use_advance_lead)
           current_estep_rate[current_block->active_extruder] = ((unsigned long)acc_step_rate * current_block->e_speed_multiplier8) >> 8;
-        }
-      #endif
 
-      #if ENABLED(ADVANCE)
+      #elif ENABLED(ADVANCE)
 
         advance += advance_rate * step_loops;
         //NOLESS(advance, current_block->advance);
         e_steps[current_block->active_extruder] += ((advance >> 8) - old_advance);
         old_advance = advance >> 8;
 
-      #endif //ADVANCE
+      #endif // ADVANCE or LIN_ADVANCE
+
     }
     else if (step_events_completed > (unsigned long)current_block->decelerate_after) {
       MultiU24X32toH16(step_rate, deceleration_time, current_block->acceleration_rate);
       deceleration_time += timer;
       
       #if ENABLED(LIN_ADVANCE)
-        if (current_block->use_advance_lead){
+
+        if (current_block->use_advance_lead)
           current_estep_rate[current_block->active_extruder] = ((unsigned long)step_rate * current_block->e_speed_multiplier8) >> 8;
-        }
-      #endif
 
-      #if ENABLED(ADVANCE)
+      #elif ENABLED(ADVANCE)
+
         advance -= advance_rate * step_loops;
         NOLESS(advance, final_advance);
 
         uint32_t advance_whole = advance >> 8;
         e_steps[current_block->active_extruder] += advance_whole - old_advance;
         old_advance = advance_whole;
-      #endif //ADVANCE
+
+      #endif // ADVANCE or LIN_ADVANCE
     }
     else {
-      #ifdef LIN_ADVANCE
-        if (current_block->use_advance_lead){
+      #if ENABLED(LIN_ADVANCE)
+        if (current_block->use_advance_lead)
           current_estep_rate[current_block->active_extruder] = final_estep_rate;
-        }
       #endif
-      
+
       OCR1A = OCR1A_nominal;
       // ensure we're running at the correct step rate, even if we just came off an acceleration
       step_loops = step_loops_nominal;
   }
 }
 
-#if ENABLED(ADVANCE)
+#if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+
   // Timer interrupt for E. e_steps is set in the main routine;
   // Timer 0 is shared with millies
   ISR(TIMER0_COMPA_vect) { Stepper::advance_isr(); }
 
   void Stepper::advance_isr() {
+
     old_OCR0A += 52; // ~10kHz interrupt (250000 / 26 = 9615kHz)
     OCR0A = old_OCR0A;
 
         #endif
       #endif
     }
-  }
 
-#endif // ADVANCE
-
-#if ENABLED(LIN_ADVANCE)
-unsigned char old_OCR0A;
-// Timer interrupt for E. e_steps is set in the main routine;
-// Timer 0 is shared with millies
-ISR(TIMER0_COMPA_vect) { stepper.advance_isr(); }
-
-void Stepper::advance_isr() {
-  old_OCR0A += 52; // ~10kHz interrupt (250000 / 26 = 9615kHz) war 52
-  OCR0A = old_OCR0A;
-
-#define STEP_E_ONCE(INDEX) \
-  if (e_steps[INDEX] != 0) { \
-    E## INDEX ##_STEP_WRITE(INVERT_E_STEP_PIN); \
-    if (e_steps[INDEX] < 0) { \
-      E## INDEX ##_DIR_WRITE(INVERT_E## INDEX ##_DIR); \
-      e_steps[INDEX]++; \
-    } \
-    else if (e_steps[INDEX] > 0) { \
-      E## INDEX ##_DIR_WRITE(!INVERT_E## INDEX ##_DIR); \
-      e_steps[INDEX]--; \
-    } \
-    E## INDEX ##_STEP_WRITE(!INVERT_E_STEP_PIN); \
   }
 
-  // Step all E steppers that have steps, up to 4 steps per interrupt
-  for (unsigned char i = 0; i < 4; i++) {
-    #if EXTRUDERS > 3
-      switch(current_block->active_extruder){case 3:STEP_E_ONCE(3);break;case 2:STEP_E_ONCE(2);break;case 1:STEP_E_ONCE(1);break;default:STEP_E_ONCE(0);}
-    #elif EXTRUDERS > 2
-      switch(current_block->active_extruder){case 2:STEP_E_ONCE(2);break;case 1:STEP_E_ONCE(1);break;default:STEP_E_ONCE(0);}
-    #elif EXTRUDERS > 1
-      #if DISABLED(DUAL_X_CARRIAGE)
-        if(current_block->active_extruder == 1){STEP_E_ONCE(1)}else{STEP_E_ONCE(0);}
-      #else
-        extern bool extruder_duplication_enabled;
-        if(extruder_duplication_enabled){
-          STEP_E_ONCE(0);
-          STEP_E_ONCE(1);
-        }else {
-          if(current_block->active_extruder == 1){STEP_E_ONCE(1)}else{STEP_E_ONCE(0);}
-        }
-      #endif
-    #else
-      STEP_E_ONCE(0);
-    #endif
-  }
-}
-#endif // LIN_ADVANCE
+#endif // ADVANCE or LIN_ADVANCE
 
 void Stepper::init() {
 
   OCR1A = 0x4000;
   TCNT1 = 0;
   ENABLE_STEPPER_DRIVER_INTERRUPT();
-  
-  #if ENABLED(LIN_ADVANCE)
-    for (int i = 0; i < EXTRUDERS; i++){
-      e_steps[i] = 0;
-      current_adv_steps[i] = 0;
-    }
-    #if defined(TCCR0A) && defined(WGM01)
-      CBI(TCCR0A, WGM01);
-      CBI(TCCR0A, WGM00);
+
+  #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+
+    #if ENABLED(LIN_ADVANCE)
+
+      for (int i = 0; i < EXTRUDERS; i++) {
+        e_steps[i] = 0;
+        current_adv_steps[i] = 0;
+      }
+
+    #elif ENABLED(ADVANCE)
+
+      for (uint8_t i = 0; i < EXTRUDERS; i++) e_steps[i] = 0;
+
     #endif
-    SBI(TIMSK0, OCIE0A);
-  #endif //LIN_ADVANCE
 
-  #if ENABLED(ADVANCE)
     #if defined(TCCR0A) && defined(WGM01)
       CBI(TCCR0A, WGM01);
       CBI(TCCR0A, WGM00);
     #endif
-    for (uint8_t i = 0; i < EXTRUDERS; i++) e_steps[i] = 0;
     SBI(TIMSK0, OCIE0A);
-  #endif //ADVANCE
+
+  #endif // ADVANCE or LIN_ADVANCE
 
   endstops.enable(true); // Start with endstops active. After homing they can be disabled
   sei();
 }
 
 #if ENABLED(LIN_ADVANCE)
+
   void Stepper::advance_M905() {
     if (code_seen('K')) extruder_advance_k = code_value();
     SERIAL_ECHO_START;
-    SERIAL_ECHOPGM("Advance factor:");
-    SERIAL_CHAR(' ');
-    SERIAL_ECHOLN(extruder_advance_k);
+    SERIAL_ECHOPAIR("Advance factor: ", extruder_advance_k);
+    SERIAL_EOL;
   }
 
-  int Stepper::get_advance_k(){
-    return extruder_advance_k;
-  }
-#endif
+#endif // LIN_ADVANCE

Marlin/stepper.h

       static bool performing_homing;
     #endif
 
-    #if ENABLED(ADVANCE)
-      static long e_steps[EXTRUDERS];
-    #endif
-    
-    #if ENABLED(LIN_ADVANCE)
-      int extruder_advance_k = LIN_K;
-    #endif
-
   private:
 
     static unsigned char last_direction_bits;        // The next stepping-bits to be output
     static long counter_X, counter_Y, counter_Z, counter_E;
     static volatile unsigned long step_events_completed; // The number of step events executed in the current block
 
-    #if ENABLED(ADVANCE)
+    #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
       static unsigned char old_OCR0A;
-      static long advance_rate, advance, old_advance, final_advance;
-    #endif
-    
-    #if ENABLED(LIN_ADVANCE)
-      unsigned char old_OCR0A;
-      volatile int e_steps[EXTRUDERS];
-      int final_estep_rate;
-      int current_estep_rate[EXTRUDERS]; //Actual extruder speed [steps/s]
-      int current_adv_steps[EXTRUDERS]; //The amount of current added esteps due to advance. Think of it as the current amount of pressure applied to the spring (=filament).
-    #endif
+      static volatile unsigned char eISR_Rate;
+      #if ENABLED(LIN_ADVANCE)
+        static volatile int e_steps[EXTRUDERS];
+        static int extruder_advance_k;
+        static int final_estep_rate;
+        static int current_estep_rate[EXTRUDERS]; // Actual extruder speed [steps/s]
+        static int current_adv_steps[EXTRUDERS];  // The amount of current added esteps due to advance.
+                                                  // i.e., the current amount of pressure applied
+                                                  // to the spring (=filament).
+      #else
+        static long e_steps[EXTRUDERS];
+        static long advance_rate, advance, final_advance;
+        static long old_advance;
+      #endif
+    #endif // ADVANCE or LIN_ADVANCE
 
     static long acceleration_time, deceleration_time;
     //unsigned long accelerate_until, decelerate_after, acceleration_rate, initial_rate, final_rate, nominal_rate;
 
     static void isr();
 
-    #if ENABLED(ADVANCE)
+    #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
       static void advance_isr();
     #endif
-    
-    #if ENABLED(LIN_ADVANCE)
-      void advance_isr();
-      void advance_M905();
-      int get_advance_k();
-    #endif
 
     //
     // Block until all buffered steps are executed
       return endstops_trigsteps[axis] / planner.axis_steps_per_mm[axis];
     }
 
+    #if ENABLED(LIN_ADVANCE)
+      void advance_M905();
+      FORCE_INLINE int get_advance_k() { return extruder_advance_k; }
+    #endif
+
   private:
 
     static FORCE_INLINE unsigned short calc_timer(unsigned short step_rate) {
       OCR1A = acceleration_time;
       
       #if ENABLED(LIN_ADVANCE)
-        if (current_block->use_advance_lead){
+        if (current_block->use_advance_lead) {
           current_estep_rate[current_block->active_extruder] = ((unsigned long)acc_step_rate * current_block->e_speed_multiplier8) >> 8;
           final_estep_rate = (current_block->nominal_rate * current_block->e_speed_multiplier8) >> 8;
         }
 
 };
 
-#endif // STEPPER_H
+#endif // STEPPER_H