Minor bug fixes: Homing travel calculations. Cycle resuming after spindle and dwell commands.

- Homing travel calculations fixed. It was computing the min travel rather than max. - Auto-start disable and pausing after spindle or dwell commands. Related to plan_synchronize() function call. Now fixed, but still need to work on the system state. - Pushed a fix to make this branch more Arduino IDE compatible. Removed extern call in nuts_bolts.c - Updated the stepper configuration option of enabling or disabling the new Adaptive Multi-Axis Step Smoothing Algorithm. Now works either way. - Updated some copyright info.
2013-12-30 22:02:05 -07:00 · 2013-12-30 22:02:05 -07:00 · f10bad43b2
commit f10bad43b2
parent 47cd40c8dc
30 changed files with 102 additions and 98 deletions
--- a/config.h
+++ b/config.h
@ -2,7 +2,7 @@
  config.h - compile time configuration
  Part of Grbl

-  Copyright (c) 2011-2013 Sungeun K. Jeon
+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud

  Grbl is free software: you can redistribute it and/or modify
@ -88,7 +88,7 @@
 // set this only as high as needed. Approximate successful values can widely range from 50 to 200 or more.
 #define ACCELERATION_TICKS_PER_SECOND 100 

-#define ACTIVE_MULTI_AXIS_STEP_SMOOTHING 
+#define ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING 
 #define ENABLE_SOFTWARE_DEBOUNCE

 // Minimum planner junction speed. Sets the default minimum junction speed the planner plans to at
--- a/coolant_control.c
+++ b/coolant_control.c
@ -2,7 +2,7 @@
  coolant_control.c - coolant control methods
  Part of Grbl

-  Copyright (c) 2012 Sungeun K. Jeon
+  Copyright (c) 2012-2014 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/coolant_control.h
+++ b/coolant_control.h
@ -2,7 +2,7 @@
  coolant_control.h - spindle control methods
  Part of Grbl

-  Copyright (c) 2012 Sungeun K. Jeon
+  Copyright (c) 2012-2014 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/cpu_map.h
+++ b/cpu_map.h
@ -2,7 +2,7 @@
  cpu_map.h - CPU and pin mapping configuration file
  Part of Grbl

-  Copyright (c) 2013 Sungeun K. Jeon
+  Copyright (c) 2013-2014 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/defaults.h
+++ b/defaults.h
@ -2,7 +2,7 @@
  defaults.h - defaults settings configuration file
  Part of Grbl

-  Copyright (c) 2012-2013 Sungeun K. Jeon
+  Copyright (c) 2012-2014 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/gcode.c
+++ b/gcode.c
@ -2,8 +2,8 @@
  gcode.c - rs274/ngc parser.
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon
  
  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/gcode.h
+++ b/gcode.h
@ -2,8 +2,8 @@
  gcode.h - rs274/ngc parser.
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon
  
  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/limits.c
+++ b/limits.c
@ -2,8 +2,8 @@
  limits.c - code pertaining to limit-switches and performing the homing cycle
  Part of Grbl

+  Copyright (c) 2012-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2012-2013 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
@ -132,11 +132,12 @@ void limits_go_home(uint8_t cycle_mask, bool approach, float homing_rate)
  else { invert_pin = !approach; }
  
  // Determine travel distance to the furthest homing switch based on user max travel settings.
+  // NOTE: settings.max_travel[] is stored as a negative value.
  float max_travel = settings.max_travel[X_AXIS];
-  if (max_travel < settings.max_travel[Y_AXIS]) { max_travel = settings.max_travel[Y_AXIS]; }
-  if (max_travel < settings.max_travel[Z_AXIS]) { max_travel = settings.max_travel[Z_AXIS]; }
-  max_travel *= 1.25; // Ensure homing switches engaged by over-estimating max travel.
-  if (approach) { max_travel = -max_travel; }
+  if (max_travel > settings.max_travel[Y_AXIS]) { max_travel = settings.max_travel[Y_AXIS]; }
+  if (max_travel > settings.max_travel[Z_AXIS]) { max_travel = settings.max_travel[Z_AXIS]; }
+  max_travel *= -1.25; // Ensure homing switches engaged by over-estimating max travel.
+  if (!approach) { max_travel = -max_travel; }

  // Set target location and rate for active axes.
  float target[N_AXIS];
--- a/limits.h
+++ b/limits.h
@ -2,8 +2,8 @@
  limits.h - code pertaining to limit-switches and performing the homing cycle
  Part of Grbl

+  Copyright (c) 2013-2014 Sungeun K. Jeon  
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2013 Sungeun K. Jeon  

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/main.c
+++ b/main.c
@ -2,8 +2,8 @@
  main.c - An embedded CNC Controller with rs274/ngc (g-code) support
  Part of Grbl
  
+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/motion_control.c
+++ b/motion_control.c
@ -2,8 +2,8 @@
  motion_control.c - high level interface for issuing motion commands
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon
  Copyright (c) 2011 Jens Geisler
  
  Grbl is free software: you can redistribute it and/or modify
@ -301,13 +301,7 @@ void mc_homing_cycle()
 // NOTE: This function is called from the main loop and mc_line() only and executes when one of
 // two conditions exist respectively: There are no more blocks sent (i.e. streaming is finished, 
 // single commands), or the planner buffer is full and ready to go.
-void mc_auto_cycle_start() 
-{ 
-  if (sys.auto_start) { 
-    st_cycle_start(); 
-    if (bit_isfalse(settings.flags,BITFLAG_AUTO_START)) { sys.auto_start = false; } // Reset auto start per settings.
-  }
-}
+void mc_auto_cycle_start() { if (sys.auto_start) { st_cycle_start(); } }


 // Method to ready the system to reset by setting the runtime reset command and killing any
--- a/motion_control.h
+++ b/motion_control.h
@ -2,8 +2,8 @@
  motion_control.h - high level interface for issuing motion commands
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon
  
  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/nuts_bolts.c
+++ b/nuts_bolts.c
@ -2,8 +2,8 @@
  nuts_bolts.c - Shared functions
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
@ -25,7 +25,6 @@
 #include "planner.h"

 #define MAX_INT_DIGITS 8 // Maximum number of digits in int32 (and float)
-extern float __floatunsisf (unsigned long);

 // Extracts a floating point value from a string. The following code is based loosely on
 // the avr-libc strtod() function by Michael Stumpf and Dmitry Xmelkov and many freely
@ -79,7 +78,7 @@ int read_float(char *line, uint8_t *char_counter, float *float_ptr)
  
  // Convert integer into floating point.
  float fval;
-  fval = __floatunsisf(intval);
+  fval = (float)intval;
  
  // Apply decimal. Should perform no more than two floating point multiplications for the
  // expected range of E0 to E-4.
--- a/nuts_bolts.h
+++ b/nuts_bolts.h
@ -2,8 +2,8 @@
  nuts_bolts.h - Header file for shared definitions, variables, and functions
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon  
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon  

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/planner.c
+++ b/planner.c
@ -2,7 +2,7 @@
  planner.c - buffers movement commands and manages the acceleration profile plan
  Part of Grbl

-  Copyright (c) 2011-2013 Sungeun K. Jeon
+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
  Copyright (c) 2011 Jens Geisler  
  
@ -255,7 +255,8 @@ uint8_t plan_check_full_buffer()
 // during a synchronize call, if it should happen. Also, waits for clean cycle end.
 void plan_synchronize()
 {
-  sys.auto_start = true; // Set auto start to resume cycle after synchronize and caller completes.
+  // Check and set auto start to resume cycle after synchronize and caller completes.
+  if (sys.state == STATE_CYCLE) { sys.auto_start = true; }
  while (plan_get_current_block() || (sys.state == STATE_CYCLE)) { 
    protocol_execute_runtime();   // Check and execute run-time commands
    if (sys.abort) { return; } // Check for system abort
--- a/planner.h
+++ b/planner.h
@ -2,7 +2,7 @@
  planner.h - buffers movement commands and manages the acceleration profile plan
  Part of Grbl

-  Copyright (c) 2011-2013 Sungeun K. Jeon 
+  Copyright (c) 2011-2014 Sungeun K. Jeon 
  Copyright (c) 2009-2011 Simen Svale Skogsrud

  Grbl is free software: you can redistribute it and/or modify
--- a/print.c
+++ b/print.c
@ -2,8 +2,8 @@
  print.c - Functions for formatting output strings
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/print.h
+++ b/print.h
@ -2,8 +2,8 @@
  print.h - Functions for formatting output strings
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/protocol.c
+++ b/protocol.c
@ -2,8 +2,8 @@
  protocol.c - the serial protocol master control unit
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon  
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon  

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/protocol.h
+++ b/protocol.h
@ -2,8 +2,8 @@
  protocol.h - the serial protocol master control unit
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/report.c
+++ b/report.c
@ -2,7 +2,7 @@
  report.c - reporting and messaging methods
  Part of Grbl

-  Copyright (c) 2012-2013 Sungeun K. Jeon  
+  Copyright (c) 2012-2014 Sungeun K. Jeon  

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/report.h
+++ b/report.h
@ -2,7 +2,7 @@
  report.h - reporting and messaging methods
  Part of Grbl

-  Copyright (c) 2012-2013 Sungeun K. Jeon
+  Copyright (c) 2012-2014 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/serial.c
+++ b/serial.c
@ -2,8 +2,8 @@
  serial.c - Low level functions for sending and recieving bytes via the serial port
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/serial.h
+++ b/serial.h
@ -2,8 +2,8 @@
  serial.c - Low level functions for sending and recieving bytes via the serial port
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/settings.c
+++ b/settings.c
@ -2,8 +2,8 @@
  settings.c - eeprom configuration handling 
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon  
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon  

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/settings.h
+++ b/settings.h
@ -2,8 +2,8 @@
  settings.h - eeprom configuration handling 
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon
  
  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/spindle_control.c
+++ b/spindle_control.c
@ -2,8 +2,8 @@
  spindle_control.c - spindle control methods
  Part of Grbl

+  Copyright (c) 2012-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/spindle_control.h
+++ b/spindle_control.h
@ -2,8 +2,8 @@
  spindle_control.h - spindle control methods
  Part of Grbl

+  Copyright (c) 2012-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
--- a/stepper.c
+++ b/stepper.c
@ -2,7 +2,7 @@
  stepper.c - stepper motor driver: executes motion plans using stepper motors
  Part of Grbl

-  Copyright (c) 2011-2013 Sungeun K. Jeon
+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
  
  Grbl is free software: you can redistribute it and/or modify
@ -63,7 +63,11 @@ typedef struct {
  uint16_t n_step;         // Number of step events to be executed for this segment
  uint8_t st_block_index; // Stepper block data index. Uses this information to execute this segment.
  uint16_t cycles_per_tick;  // Step distance traveled per ISR tick, aka step rate.
+  #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
    uint8_t amass_level;
+  #else
+    uint8_t prescaler;
+  #endif
 } segment_t;
 static segment_t segment_buffer[SEGMENT_BUFFER_SIZE];

@ -83,7 +87,9 @@ typedef struct {
  uint8_t step_pulse_time;  // Step pulse reset time after step rise
  uint8_t step_outbits;         // The next stepping-bits to be output
  uint8_t dir_outbits;
+  #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
    uint32_t steps[N_AXIS];
+  #endif

  uint16_t step_count;       // Steps remaining in line segment motion  
  uint8_t exec_block_index; // Tracks the current st_block index. Change indicates new block.
@ -278,7 +284,9 @@ ISR(TIMER1_COMPA_vect)
      // Initialize new step segment and load number of steps to execute
      st.exec_segment = &segment_buffer[segment_buffer_tail];
      // Initialize step segment timing per step and load number of steps to execute.
-      // TCCR1B = (TCCR1B & ~(0x07<<CS10)) | (st.exec_segment->prescaler<<CS10);
+      #ifndef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
+        TCCR1B = (TCCR1B & ~(0x07<<CS10)) | (st.exec_segment->prescaler<<CS10);
+      #endif
      OCR1A = st.exec_segment->cycles_per_tick;
      st.step_count = st.exec_segment->n_step; // NOTE: Can sometimes be zero when moving slow.
      // If the new segment starts a new planner block, initialize stepper variables and counters.
@ -292,9 +300,11 @@ ISR(TIMER1_COMPA_vect)
        st.counter_y = st.counter_x;
        st.counter_z = st.counter_x;        
      }
+      #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
        st.steps[X_AXIS] = st.exec_block->steps[X_AXIS] >> st.exec_segment->amass_level;
        st.steps[Y_AXIS] = st.exec_block->steps[Y_AXIS] >> st.exec_segment->amass_level;
        st.steps[Z_AXIS] = st.exec_block->steps[Z_AXIS] >> st.exec_segment->amass_level;
+      #endif
    } else {
      // Segment buffer empty. Shutdown.
      st_go_idle();
@ -307,21 +317,33 @@ ISR(TIMER1_COMPA_vect)
  st.step_outbits = 0; 

  // Execute step displacement profile by Bresenham line algorithm
+  #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
    st.counter_x += st.steps[X_AXIS];
+  #else
+    st.counter_x += st.exec_block->steps[X_AXIS];
+  #endif  
  if (st.counter_x > st.exec_block->step_event_count) {
    st.step_outbits |= (1<<X_STEP_BIT);
    st.counter_x -= st.exec_block->step_event_count;
    if (st.exec_block->direction_bits & (1<<X_DIRECTION_BIT)) { sys.position[X_AXIS]--; }
    else { sys.position[X_AXIS]++; }
  }
+  #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
    st.counter_y += st.steps[Y_AXIS];
+  #else
+    st.counter_y += st.exec_block->steps[Y_AXIS];
+  #endif    
  if (st.counter_y > st.exec_block->step_event_count) {
    st.step_outbits |= (1<<Y_STEP_BIT);
    st.counter_y -= st.exec_block->step_event_count;
    if (st.exec_block->direction_bits & (1<<Y_DIRECTION_BIT)) { sys.position[Y_AXIS]--; }
    else { sys.position[Y_AXIS]++; }
  }
+  #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
    st.counter_z += st.steps[Z_AXIS];
+  #else
+    st.counter_z += st.exec_block->steps[Z_AXIS];
+  #endif  
  if (st.counter_z > st.exec_block->step_event_count) {
    st.step_outbits |= (1<<Z_STEP_BIT);
    st.counter_z -= st.exec_block->step_event_count;
@ -433,6 +455,7 @@ void st_cycle_start()
    sys.state = STATE_CYCLE;
    st_prep_buffer(); // Initialize step segment buffer before beginning cycle.
    st_wake_up();
+    if (bit_isfalse(settings.flags,BITFLAG_AUTO_START)) { sys.auto_start = false; } // Reset auto start per settings.
  }
 }

@ -500,8 +523,8 @@ void st_update_plan_block_parameters()
 */
 void st_prep_buffer()
 {
-  if (sys.state == STATE_QUEUED) { return; } // Block until a motion state is issued
  while (segment_buffer_tail != segment_next_head) { // Check if we need to fill the buffer.
+    if (sys.state == STATE_QUEUED) { return; } // Block until a motion state is issued    

    // Determine if we need to load a new planner block or if the block remainder is replanned. 
    if (pl_block == NULL) {
@ -520,16 +543,16 @@ void st_prep_buffer()
        // when the segment buffer completes the planner block, it may be discarded immediately.
        st_prep_block = &st_block_buffer[prep.st_block_index];
        st_prep_block->direction_bits = pl_block->direction_bits;
-        #ifdef ACTIVE_MULTI_AXIS_STEP_SMOOTHING
-          st_prep_block->steps[X_AXIS] = pl_block->steps[X_AXIS] << MAX_AMASS_LEVEL;
-          st_prep_block->steps[Y_AXIS] = pl_block->steps[Y_AXIS] << MAX_AMASS_LEVEL;
-          st_prep_block->steps[Z_AXIS] = pl_block->steps[Z_AXIS] << MAX_AMASS_LEVEL;
-          st_prep_block->step_event_count = pl_block->step_event_count << MAX_AMASS_LEVEL;
-        #else
+        #ifndef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING
          st_prep_block->steps[X_AXIS] = pl_block->steps[X_AXIS];
          st_prep_block->steps[Y_AXIS] = pl_block->steps[Y_AXIS];
          st_prep_block->steps[Z_AXIS] = pl_block->steps[Z_AXIS];
          st_prep_block->step_event_count = pl_block->step_event_count;
+        #else
+          st_prep_block->steps[X_AXIS] = pl_block->steps[X_AXIS] << MAX_AMASS_LEVEL;
+          st_prep_block->steps[Y_AXIS] = pl_block->steps[Y_AXIS] << MAX_AMASS_LEVEL;
+          st_prep_block->steps[Z_AXIS] = pl_block->steps[Z_AXIS] << MAX_AMASS_LEVEL;
+          st_prep_block->step_event_count = pl_block->step_event_count << MAX_AMASS_LEVEL;
        #endif
        
        // Initialize segment buffer data for generating the segments.
@ -701,7 +724,7 @@ void st_prep_buffer()
    float inv_rate = dt/(prep.steps_remaining-steps_remaining);
    cycles = ceil( (TICKS_PER_MICROSECOND*1000000*60)*inv_rate ); // (cycles/step)
    
-    #ifdef ACTIVE_MULTI_AXIS_STEP_SMOOTHING        
+    #ifdef ADAPTIVE_MULTI_AXIS_STEP_SMOOTHING        
      // Compute step timing and multi-axis smoothing level.
      // NOTE: Only one prescalar is required with AMASS enabled.
      if (cycles > AMASS_LEVEL1) { 
@ -712,8 +735,24 @@ void st_prep_buffer()
        cycles >>= prep_segment->amass_level; 
        prep_segment->n_step <<= prep_segment->amass_level;
      } else { prep_segment->amass_level = 0; }
-      if (cycles < (1UL << 16)) { prep_segment->cycles_per_tick = cycles; }
-      else { prep_segment->cycles_per_tick = 0xffff; } // Just set the slowest speed possible. (4.1ms @ 16MHz)
+      if (cycles < (1UL << 16)) { prep_segment->cycles_per_tick = cycles; } // < 65536 (4.1ms @ 16MHz)
+      else { prep_segment->cycles_per_tick = 0xffff; } // Just set the slowest speed possible.
+    #else 
+      // Compute step timing and timer prescalar for normal step generation.
+      if (cycles < (1UL << 16)) { // < 65536  (4.1ms @ 16MHz)
+        prep_segment->prescaler = 1; // prescaler: 0
+        prep_segment->cycles_per_tick = cycles;
+      } else if (cycles < (1UL << 19)) { // < 524288 (32.8ms@16MHz)
+        prep_segment->prescaler = 2; // prescaler: 8
+        prep_segment->cycles_per_tick = cycles >> 3;
+      } else { 
+        prep_segment->prescaler = 3; // prescaler: 64
+        if (cycles < (1UL << 22)) { // < 4194304 (262ms@16MHz)
+          prep_segment->cycles_per_tick =  cycles >> 6;
+        } else { // Just set the slowest speed possible.
+          prep_segment->cycles_per_tick = 0xffff;
+        }
+      }
    #endif

    // Determine end of segment conditions. Setup initial conditions for next segment.
@ -754,8 +793,6 @@ void st_prep_buffer()
 // int32_t blength = segment_buffer_head - segment_buffer_tail;
 // if (blength < 0) { blength += SEGMENT_BUFFER_SIZE; } 
 // printInteger(blength);
-    
-    if (sys.state & (STATE_QUEUED | STATE_HOMING)) { return; } // Force exit or one prepped segment.
  } 
 }      

@ -785,31 +822,3 @@ void st_prep_buffer()
     we know when the plan is feasible in the context of what's already in the code and not
     require too much more code? 
 */
-
-// static void st_config_step_timer(uint32_t cycles) 
-// {
-//   if (cycles < (1UL << 16)) { // < 65536  (4.1ms @ 16MHz)
-//     prep_segment->prescaler = 1; // prescaler: 0
-//     prep_segment->cycles_per_tick = cycles;
-//   } else {
-//     prep_segment->prescaler = 2; // prescaler: 8
-//     if (cycles < (1UL << 19)) { // < 524288 (32.8ms@16MHz)
-//       prep_segment->cycles_per_tick = cycles >> 3;
-// 
-// //   } else if (cycles < (1UL << 22)) { // < 4194304 (262ms@16MHz)
-// //     prep_segment->prescaler = 3; // prescaler: 64
-// //     prep_segment->cycles_per_tick =  cycles >> 6;
-// //   } else if (cycles < (1UL << 24)) { // < 16777216 (1.05sec@16MHz)
-// //     prep_segment->prescaler = 4; // prescaler: 256
-// //     prep_segment->cycles_per_tick =  (cycles >> 8);
-// //   } else {
-// //     prep_segment->prescaler = 5; // prescaler: 1024
-// //     if (cycles < (1UL << 26)) { // < 67108864 (4.19sec@16MHz)
-// //       prep_segment->cycles_per_tick = (cycles >> 10);
-// 
-//     } else { // Just set the slowest speed possible.
-//       prep_segment->cycles_per_tick = 0xffff;
-//     }
-//     printString("X");
-//   }
-// }
--- a/stepper.h
+++ b/stepper.h
@ -2,8 +2,8 @@
  stepper.h - stepper motor driver: executes motion plans of planner.c using the stepper motors
  Part of Grbl

+  Copyright (c) 2011-2014 Sungeun K. Jeon
  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011-2013 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by