Improved homing cycle. New settings: homing enable/rates, debounce and step idle lock time.

- Homing cycle will now cycle twice (spec more/less in config) to
improve repeatability and accuracy by decreasing overshoot.

- New Grbl settings added: Enable/disable homing cycles, homing seek
and feed rates, switch debounce delay, and stepper idle lock time.

- Please note that these settings may change upon the next push, since
there will be more added soon. Grbl *should* not re-write your old
settings, just re-write the new ones. So, make sure you keep these
written down somewhere in case they get lost from a code bug.

- Refactored settings migration to be a little smaller and managable
going forward.

config.h

@@ -84,15 +84,6 @@
 // This parameter must be one or greater, currently supporting up to a value of 6.
 #define N_COORDINATE_SYSTEM 1
 
-// This parameter sets the delay time before disabling the steppers after the final block of movement.
-// A short delay ensures the steppers come to a complete stop and the residual inertial force in the 
-// CNC axes don't cause the axes to drift off position. This is particularly important when manually 
-// entering g-code into grbl, i.e. locating part zero or simple manual machining. If the axes drift,
-// grbl has no way to know this has happened, since stepper motors are open-loop control. Depending
-// on the machine, this parameter may need to be larger or smaller than the default time.
-// NOTE: If the define commented, the stepper lock will be disabled upon compiling.
-#define STEPPER_IDLE_LOCK_TIME 25 // (milliseconds) - Integer > 0
-
 // The temporal resolution of the acceleration management subsystem. Higher number give smoother
 // acceleration but may impact performance.
 // NOTE: Increasing this parameter will help any resolution related issues, especially with machines 
@@ -102,7 +93,7 @@
 // round-off can be great enough to cause problems and/or it's too fast for the Arduino. The correct
 // value for this parameter is machine dependent, so it's advised to set this only as high as needed.
 // Approximate successful values can range from 30L to 100L or more.
-#define ACCELERATION_TICKS_PER_SECOND 50L
+#define ACCELERATION_TICKS_PER_SECOND 60L
 
 // Minimum planner junction speed. Sets the default minimum speed the planner plans for at the end
 // of the buffer and all stops. This should not be much greater than zero and should only be changed
@@ -129,6 +120,11 @@
 // time step. Also, keep in mind that the Arduino delay timer is not very accurate for long delays.
 #define DWELL_TIME_STEP 50 // Integer (1-255) (milliseconds)
 
+// Number of homing cycles performed after when the machine initially jogs to limit switches.
+// This help in preventing overshoot and should improve repeatability. This value should be one or 
+// greater.
+#define N_HOMING_CYCLE 2 // Integer (1-128)
+
 // ---------------------------------------------------------------------------------------
 // FOR ADVANCED USERS ONLY: 
 
@@ -174,7 +170,14 @@
   #define DECIMAL_MULTIPLIER 100
 #endif
 
-//  Limit step rate for homing
+// This parameter sets the delay time before disabling the steppers after the final block of movement.
-#define LIMIT_DEBOUNCE 50  // Limit switch debounce delay (in ms)
+// A short delay ensures the steppers come to a complete stop and the residual inertial force in the 
+// CNC axes don't cause the axes to drift off position. This is particularly important when manually 
+// entering g-code into grbl, i.e. locating part zero or simple manual machining. If the axes drift,
+// grbl has no way to know this has happened, since stepper motors are open-loop control. Depending
+// on the machine, this parameter may need to be larger or smaller than the default time.
+// NOTE: If the define commented, the stepper lock will be disabled upon compiling.
+// -> NOW INSTALLED IN SETTINGS #define STEPPER_IDLE_LOCK_TIME 25 // (milliseconds) - Integer > 0
+
 
 #endif

gcode.c

@@ -179,7 +179,13 @@ uint8_t gc_execute_line(char *line)
           case 19: select_plane(Y_AXIS, Z_AXIS, X_AXIS); break;
           case 20: gc.inches_mode = true; break;
           case 21: gc.inches_mode = false; break;
-          case 28: case 30: non_modal_action = NON_MODAL_GO_HOME; break;
+          case 28: case 30: 
+            if (bit_istrue(settings.flags,FLAG_BIT_HOMING_ENABLE)) {
+              non_modal_action = NON_MODAL_GO_HOME; 
+            } else {
+              FAIL(STATUS_SETTING_DISABLED);
+            }
+            break;
           case 53: absolute_override = true; break;
           case 54: case 55: case 56: case 57: case 58: case 59:
             int_value -= 54; // Compute coordinate system row index (0=G54,1=G55,...)

limits.c

@@ -156,26 +156,28 @@ static void homing_cycle(bool x_axis, bool y_axis, bool z_axis, int8_t pos_dir,
   }
 }
 
-static void approach_limit_switch(bool x, bool y, bool z) 
-{
-  homing_cycle(x, y, z, true, false, settings.default_seek_rate);
-}
-
-
-static void leave_limit_switch(bool x, bool y, bool z) {
-  homing_cycle(x, y, z, false, true, settings.default_feed_rate);
-}
 
 void limits_go_home() 
 {
   plan_synchronize();  // Empty all motions in buffer.
   
-  // Jog all axes toward home to engage their limit switches.
+  // Jog all axes toward home to engage their limit switches at faster homing seek rate.
-  approach_limit_switch(false, false, true); // First home the z axis
+  homing_cycle(false, false, true, true, false, settings.homing_seek_rate); // First jog the z axis
-  approach_limit_switch(true, true, false);  // Then home the x and y axis
+  homing_cycle(true, true, false, true, false, settings.homing_seek_rate);   // Then jog the x and y axis
-  delay_ms(LIMIT_DEBOUNCE); // Delay to debounce signal before leaving limit switches
+  delay_ms(settings.homing_debounce_delay); // Delay to debounce signal
     
-  // Now carefully leave the limit switches
+  // Now in proximity of all limits. Carefully leave and approach switches in multiple cycles
-  leave_limit_switch(true,true,true);
+  // to precisely hone in on the machine zero location. Moves at slower homing feed rate.
-  delay_ms(LIMIT_DEBOUNCE); // Delay to debounce signal before exiting routine
+  int8_t n_cycle = N_HOMING_CYCLE;
+  while (n_cycle--) {
+    // Leave all switches to release them. After cycles complete, this is machine zero.
+    homing_cycle(true, true, true, false, true, settings.homing_feed_rate);
+    delay_ms(settings.homing_debounce_delay);
+    
+    if (n_cycle > 0) {
+      // Re-approach all switches to re-engage them.
+      homing_cycle(true, true, true, true, false, settings.homing_feed_rate);
+      delay_ms(settings.homing_debounce_delay);
+    }
+  }
 }

protocol.c

@@ -57,6 +57,8 @@ static void status_message(int status_code)
       printPgmString(PSTR("Modal group violation\r\n")); break;
       case STATUS_INVALID_COMMAND:
       printPgmString(PSTR("Invalid command\r\n")); break;
+      case STATUS_SETTING_DISABLED:
+      printPgmString(PSTR("Grbl setting disabled\r\n")); break;
       default:
       printInteger(status_code);
       printPgmString(PSTR("\r\n"));

protocol.h

@@ -28,6 +28,7 @@
 #define STATUS_FLOATING_POINT_ERROR 4
 #define STATUS_MODAL_GROUP_VIOLATION 5
 #define STATUS_INVALID_COMMAND 6
+#define STATUS_SETTING_DISABLED 7
 
 // Initialize the serial protocol
 void protocol_init();

settings.c

@@ -3,7 +3,7 @@
   Part of Grbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011 Sungeun K. Jeon  
+  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
@@ -42,6 +42,19 @@ typedef struct {
   float mm_per_arc_segment;
 } settings_v1_t;
 
+// Version 2,3,4 outdated settings record
+typedef struct {
+  float steps_per_mm[3];
+  uint8_t microsteps;
+  uint8_t pulse_microseconds;
+  float default_feed_rate;
+  float default_seek_rate;
+  uint8_t invert_mask;
+  float mm_per_arc_segment;
+  float acceleration;
+  float junction_deviation;
+} settings_v2_v4_t;
+
 // Default settings (used when resetting eeprom-settings)
 #define MICROSTEPS 8
 #define DEFAULT_X_STEPS_PER_MM (94.488188976378*MICROSTEPS)
@@ -54,7 +67,15 @@ typedef struct {
 #define DEFAULT_ACCELERATION (DEFAULT_FEEDRATE*60*60/10.0) // mm/min^2
 #define DEFAULT_JUNCTION_DEVIATION 0.05 // mm
 #define DEFAULT_STEPPING_INVERT_MASK ((1<<X_STEP_BIT)|(1<<Y_STEP_BIT)|(1<<Z_STEP_BIT))
-// #define DEFAULT_AUTO_START 1 // Boolean
+
+// Developmental default settings
+#define DEFAULT_HOMING_ENABLE 0  // false
+#define DEFAULT_HOMING_RAPID_FEEDRATE 250.0 // mm/min
+#define DEFAULT_HOMING_FEEDRATE 50 // mm/min
+#define DEFAULT_HOMING_DEBOUNCE_DELAY 100 // msec (0-65k)
+#define DEFAULT_STEPPER_IDLE_LOCK_TIME 25 // msec (0-255)
+// #define DEFAULT_AUTO_START 1 // true
+// #define DEFAULT_BLOCK_DELETE 0  // false
 
 void settings_reset() {
   settings.steps_per_mm[X_AXIS] = DEFAULT_X_STEPS_PER_MM;
@@ -81,8 +102,12 @@ void settings_dump() {
   printPgmString(PSTR(" (step port invert mask. binary = ")); print_uint8_base2(settings.invert_mask);  
   printPgmString(PSTR(")\r\n$8 = ")); printFloat(settings.acceleration/(60*60)); // Convert from mm/min^2 for human readability
   printPgmString(PSTR(" (acceleration in mm/sec^2)\r\n$9 = ")); printFloat(settings.junction_deviation);
-  printPgmString(PSTR(" (cornering junction deviation in mm)"));//\r\n$10 = ")); // printInteger(settings.auto_start);
+  printPgmString(PSTR(" (cornering junction deviation in mm)\r\n$10 = ")); printInteger(bit_istrue(settings.flags,FLAG_BIT_HOMING_ENABLE));
-//   printPgmString(PSTR(" (auto-start boolean)"));
+  printPgmString(PSTR(" (boolean homing enable)\r\n$11 = ")); printFloat(settings.homing_feed_rate);
+  printPgmString(PSTR(" (mm/min homing feed rate)\r\n$12 = ")); printFloat(settings.homing_seek_rate);
+  printPgmString(PSTR(" (mm/min homing seek rate)\r\n$13 = ")); printInteger(settings.homing_debounce_delay);
+  printPgmString(PSTR(" (milliseconds homing debounce delay)\r\n$14 = ")); printInteger(settings.stepper_idle_lock_time);
+  printPgmString(PSTR(" (milliseconds stepper idle lock time)\r\n")); 
   printPgmString(PSTR("\r\n'$x=value' to set parameter or just '$' to dump current settings\r\n"));
 }
 
@@ -126,33 +151,60 @@ int read_settings() {
     if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_t)))) {
       return(false);
     }
-  } else if (version == 1) {
+  } else {
-    // Migrate from settings version 1
+    // Incrementally update the old versions until up-to-date.
-    if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_v1_t)))) {
+    if (version == 1) {
+      // Migrate from settings version 1 to version 4.
+      if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_v1_t)))) {
+        return(false);
+      }
+      settings.acceleration = DEFAULT_ACCELERATION;
+      settings.junction_deviation = DEFAULT_JUNCTION_DEVIATION;
+    } else if ((version == 2) || (version == 3)) {
+      // Migrate from settings version 2 and 3 to version 4.
+      if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_v2_v4_t)))) {
+        return(false);
+      }
+      if (version == 2) { settings.junction_deviation = DEFAULT_JUNCTION_DEVIATION; }    
+      settings.acceleration *= 3600; // Convert to mm/min^2 from mm/sec^2
+    } 
+    if (version <= 4) {
+      // Migrate from settings version 4 to current version.
+      if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_v2_v4_t)))) {
+        return(false);
+      }
+      
+      settings.flags = 0;
+      // if (DEFAULT_AUTO_START) { settings.flags |= FLAG_BIT_AUTO_START; }
+      if (DEFAULT_HOMING_ENABLE) { settings.flags |= FLAG_BIT_HOMING_ENABLE; }  
+      settings.homing_feed_rate = DEFAULT_HOMING_FEEDRATE;
+      settings.homing_seek_rate = DEFAULT_HOMING_RAPID_FEEDRATE;
+      settings.homing_debounce_delay = DEFAULT_HOMING_DEBOUNCE_DELAY;
+      settings.stepper_idle_lock_time = DEFAULT_STEPPER_IDLE_LOCK_TIME;
+        
+      write_settings();
+      
+    } else if (version >= 50) {
+      // Developmental settings. Version numbers greater than or equal to 50 are temporary.
+      // Currently, this will update the user settings to v4 and the remainder of the settings
+      // should be re-written to the default value, if the developmental version number changed.
+      
+      // Grab settings regardless of error.
+      memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_t));
+
+      settings.flags = 0;
+      // if (DEFAULT_AUTO_START) { settings.flags |= FLAG_BIT_AUTO_START; }
+      if (DEFAULT_HOMING_ENABLE) { settings.flags |= FLAG_BIT_HOMING_ENABLE; }  
+      settings.homing_feed_rate = DEFAULT_HOMING_FEEDRATE;
+      settings.homing_seek_rate = DEFAULT_HOMING_RAPID_FEEDRATE;
+      settings.homing_debounce_delay = DEFAULT_HOMING_DEBOUNCE_DELAY;
+      settings.stepper_idle_lock_time = DEFAULT_STEPPER_IDLE_LOCK_TIME;
+      
+      write_settings();
+      
+    } else {      
       return(false);
     }
-    settings.acceleration = DEFAULT_ACCELERATION;
-    settings.junction_deviation = DEFAULT_JUNCTION_DEVIATION;
-//     settings.auto_start = DEFAULT_AUTO_START;
-    write_settings();
-  } else if ((version == 2) || (version == 3)) {
-    // Migrate from settings version 2 and 3
-    if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_t)))) {
-      return(false);
-    }
-    if (version == 2) { settings.junction_deviation = DEFAULT_JUNCTION_DEVIATION; }    
-    settings.acceleration *= 3600; // Convert to mm/min^2 from mm/sec^2
-//     settings.auto_start = DEFAULT_AUTO_START;
-    write_settings();
-//   } else if (version == 4) {
-//     // Migrate from settings version 4
-//     if (!(memcpy_from_eeprom_with_checksum((char*)&settings, 1, sizeof(settings_t)))) {
-//       return(false);
-//     }
-//     settings.auto_start = DEFAULT_AUTO_START;
-//     write_settings();
-  } else {      
-    return(false);
   }
   return(true);
 }
@@ -178,7 +230,16 @@ void settings_store_setting(int parameter, float value) {
     case 7: settings.invert_mask = trunc(value); break;
     case 8: settings.acceleration = value*60*60; break; // Convert to mm/min^2 for grbl internal use.
     case 9: settings.junction_deviation = fabs(value); break;
-//     case 10: settings.auto_start = value; break;
+    case 10:
+      if (value) { 
+        settings.flags |= FLAG_BIT_HOMING_ENABLE; 
+        printPgmString(PSTR("Install all axes limit switches before use\r\n")); 
+      } else { settings.flags &= ~FLAG_BIT_HOMING_ENABLE; }
+      break;
+    case 11: settings.homing_feed_rate = value; break;
+    case 12: settings.homing_seek_rate = value; break;
+    case 13: settings.homing_debounce_delay = round(value); break;
+    case 14: settings.stepper_idle_lock_time = round(value); break;
     default: 
       printPgmString(PSTR("Unknown parameter\r\n"));
       return;

settings.h

@@ -3,7 +3,7 @@
   Part of Grbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011 Sungeun K. Jeon
+  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
@@ -29,7 +29,11 @@
 
 // Version of the EEPROM data. Will be used to migrate existing data from older versions of Grbl
 // when firmware is upgraded. Always stored in byte 0 of eeprom
-#define SETTINGS_VERSION 4
+#define SETTINGS_VERSION 50
+
+// Define bit flag masks in settings.flag.
+#define FLAG_BIT_HOMING_ENABLE      bit(0)
+//#define FLAG_BIT_AUTO_START         bit(1)
 
 // Current global settings (persisted in EEPROM from byte 1 onwards)
 typedef struct {
@@ -42,6 +46,11 @@ typedef struct {
   float mm_per_arc_segment;
   float acceleration;
   float junction_deviation;
+  uint8_t flags;  // Contains default toggles
+  float homing_feed_rate;
+  float homing_seek_rate;
+  uint16_t homing_debounce_delay;
+  uint8_t stepper_idle_lock_time;
 } settings_t;
 extern settings_t settings;
 

stepper.c

@@ -112,9 +112,7 @@ void st_go_idle()
   TIMSK1 &= ~(1<<OCIE1A); 
   // Force stepper dwell to lock axes for a defined amount of time to ensure the axes come to a complete
   // stop and not drift from residual inertial forces at the end of the last movement.
-  #ifdef STEPPER_IDLE_LOCK_TIME
+  delay_ms(settings.stepper_idle_lock_time);   
-    _delay_ms(STEPPER_IDLE_LOCK_TIME);   
-  #endif
   // Disable steppers by setting stepper disable
   STEPPERS_DISABLE_PORT |= (1<<STEPPERS_DISABLE_BIT);
 }