Some advance modifications

Marlin/Configuration.h

 #ifdef ADVANCE
   #define EXTRUDER_ADVANCE_K .3
 
-  #define D_FILAMENT 1.7
-  #define STEPS_MM_E 65
+  #define D_FILAMENT 2.85
+  #define STEPS_MM_E 836
   #define EXTRUTION_AREA (0.25 * D_FILAMENT * D_FILAMENT * 3.14159)
   #define STEPS_PER_CUBIC_MM_E (axis_steps_per_unit[E_AXIS]/ EXTRUTION_AREA)
 

Marlin/planner.cpp

   
  // block->accelerate_until = accelerate_steps;
  // block->decelerate_after = accelerate_steps+plateau_steps;
-  
   CRITICAL_SECTION_START;  // Fill variables used by the stepper in a critical section
   if(block->busy == false) { // Don't update variables if block is busy.
     block->accelerate_until = accelerate_steps;
   // Bail if this is a zero-length block
   if (block->step_event_count <=dropsegments) { return; };
 
-  // Compute direction bits for this block
+  // Compute direction bits for this block 
   block->direction_bits = 0;
   if (target[X_AXIS] < position[X_AXIS]) { block->direction_bits |= (1<<X_AXIS); }
   if (target[Y_AXIS] < position[Y_AXIS]) { block->direction_bits |= (1<<Y_AXIS); }
     else {
       long acc_dist = estimate_acceleration_distance(0, block->nominal_rate, block->acceleration_st);
       float advance = (STEPS_PER_CUBIC_MM_E * EXTRUDER_ADVANCE_K) * 
-        (current_speed[E_AXIS] * current_speed[E_AXIS] * EXTRUTION_AREA * EXTRUTION_AREA / 3600.0)*65536;
+        (current_speed[E_AXIS] * current_speed[E_AXIS] * EXTRUTION_AREA * EXTRUTION_AREA)*256;
       block->advance = advance;
       if(acc_dist == 0) {
         block->advance_rate = 0;
         block->advance_rate = advance / (float)acc_dist;
       }
     }
+    /*
+    SERIAL_ECHO_START;
+    SERIAL_ECHOPGM("advance :");
+    SERIAL_ECHO(block->advance/256.0);
+    SERIAL_ECHOPGM("advance rate :");
+    SERIAL_ECHOLN(block->advance_rate/256.0);
+    */
   #endif // ADVANCE
 
 

Marlin/stepper.cpp

 volatile static unsigned long step_events_completed; // The number of step events executed in the current block
 #ifdef ADVANCE
   static long advance_rate, advance, final_advance = 0;
-  static short old_advance = 0;
+  static long old_advance = 0;
 #endif
-static short e_steps;
+static long e_steps;
 static unsigned char busy = false; // TRUE when SIG_OUTPUT_COMPARE1A is being serviced. Used to avoid retriggering that handler.
 static long acceleration_time, deceleration_time;
 //static unsigned long accelerate_until, decelerate_after, acceleration_rate, initial_rate, final_rate, nominal_rate;
   #ifdef ADVANCE
     advance = current_block->initial_advance;
     final_advance = current_block->final_advance;
+    // Do E steps + advance steps
+    e_steps += ((advance >>8) - old_advance);
+    old_advance = advance >>8;  
   #endif
   deceleration_time = 0;
   // step_rate to timer interval
   acceleration_time = calc_timer(acc_step_rate);
   OCR1A = acceleration_time;
   OCR1A_nominal = calc_timer(current_block->nominal_rate);
+  
+//    SERIAL_ECHO_START;
+//    SERIAL_ECHOPGM("advance :");
+//    SERIAL_ECHO(current_block->advance/256.0);
+//    SERIAL_ECHOPGM("advance rate :");
+//    SERIAL_ECHO(current_block->advance_rate/256.0);
+//    SERIAL_ECHOPGM("initial advance :");
+//  SERIAL_ECHO(current_block->initial_advance/256.0);
+//    SERIAL_ECHOPGM("final advance :");
+//    SERIAL_ECHOLN(current_block->final_advance/256.0);
+    
 }
 
 // "The Stepper Driver Interrupt" - This timer interrupt is the workhorse.  
         count_direction[E_AXIS]=-1;
       }
     #endif //!ADVANCE
+    
+
+    
     for(int8_t i=0; i < step_loops; i++) { // Take multiple steps per interrupt (For high speed moves) 
       MSerial.checkRx(); // Check for serial chars. 
       
       if (counter_e > 0) {
         counter_e -= current_block->step_event_count;
         if ((out_bits & (1<<E_AXIS)) != 0) { // - direction
-          CRITICAL_SECTION_START;
           e_steps--;
-          CRITICAL_SECTION_END;
         }
         else {
-          CRITICAL_SECTION_START;
           e_steps++;
-          CRITICAL_SECTION_END;
         }
       }    
-      // Do E steps + advance steps
-      e_steps += ((advance >> 16) - old_advance);
-      old_advance = advance >> 16;  
       #endif //ADVANCE
       
       counter_x += current_block->steps_x;
         for(int8_t i=0; i < step_loops; i++) {
           advance += advance_rate;
         }
+        //if(advance > current_block->advance) advance = current_block->advance;
+        // Do E steps + advance steps
+        e_steps += ((advance >>8) - old_advance);
+        old_advance = advance >>8;  
+        
       #endif
     } 
     else if (step_events_completed > current_block->decelerate_after) {   
         for(int8_t i=0; i < step_loops; i++) {
           advance -= advance_rate;
         }
-        if(advance < final_advance)
-          advance = final_advance;
+        if(advance < final_advance) advance = final_advance;
+        // Do E steps + advance steps
+        e_steps += ((advance >>8) - old_advance);
+        old_advance = advance >>8;  
       #endif //ADVANCE
     }
     else {
   // Timer 0 is shared with millies
   ISR(TIMER0_COMPA_vect)
   {
-    old_OCR0A += 25; // ~10kHz interrupt
+    old_OCR0A += 52; // ~10kHz interrupt (250000 / 26 = 9615kHz)
     OCR0A = old_OCR0A;
     // Set E direction (Depends on E direction + advance)
     for(unsigned char i=0; i<4;) {
         e_steps++;
         WRITE(E_STEP_PIN, HIGH);
       } 
-      if (e_steps > 0) {
+      else if (e_steps > 0) {
         WRITE(E_DIR_PIN,!INVERT_E_DIR);
         e_steps--;
         WRITE(E_STEP_PIN, HIGH);