Minor fix related to spindle_stop() crashing abort in certain cases.

- Updated spindle_stop() to fix abort bug and to be more in line with
v0.8.

config.h

@@ -115,8 +115,8 @@
 #define DWELL_TIME_STEP 50 // Integer (1-255) (milliseconds)
 
 // FOR ADVANCED USERS ONLY: Toggles XON/XOFF software flow control for serial communications. 
-// Officially not supported due to problems involving the Atmega8U2 USB-to-serial chips on current
+// Officially not supported due to problems involving the Atmega8U2 USB-to-serial chips on all 
-// future Arduinos boards. The firmware on these chips do not support XON/XOFF flow control 
+// new and future Arduinos. The firmware on these chips do not support XON/XOFF flow control 
 // characters and the intermediate buffer in the chips cause latency and overflow problems with
 // standard terminal programs. However, using specifically-programmed UI's to manage this latency 
 // problem has been confirmed to work, as well as, using older FTDI FT232RL-based Arduinos
@@ -141,4 +141,12 @@
   #define DECIMAL_MULTIPLIER 100
 #endif
 
+//  Limit step rate for homing
+#define LIMIT_STEP_RATE 1  	// (mm/min)
+
+// Debounce delay is the time delay the controller waits for a "good" signal from the limit switch.
+// A delay of 3ms to 5ms is a good starting value.
+#define LIMIT_DEBOUNCE_DELAY 5 // (milliseconds)
+
+
 #endif

gcode.c

@@ -569,7 +569,7 @@ static int next_statement(char *letter, double *double_ptr, char *line, uint8_t
   - Evaluation of expressions
   - Variables
   - Multiple home locations
-  - Multiple coordinate systems (Additional ones maybe added in config.h)
+  - Multiple coordinate systems (Up to 6 may be added via config.h)
   - Probing
   - Override control
   - Tool changes

spindle_control.c

@@ -3,6 +3,7 @@
   Part of Grbl
 
   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
@@ -27,22 +28,26 @@
 
 #include <stdint.h>
 
-// TODO: Deprecated. Need to update for new version.
+static uint8_t current_direction;
-
-static int current_direction;
 
 void spindle_init()
 {
+  current_direction = 0;
   SPINDLE_ENABLE_DDR |= (1<<SPINDLE_ENABLE_BIT);
   SPINDLE_DIRECTION_DDR |= (1<<SPINDLE_DIRECTION_BIT);  
-  spindle_run(0, 0);
+  spindle_stop();
+}
+
+void spindle_stop()
+{
+  SPINDLE_ENABLE_PORT &= ~(1<<SPINDLE_ENABLE_BIT);
 }
 
 void spindle_run(int direction, uint32_t rpm) 
 {
   if (direction != current_direction) {
     plan_synchronize();
-    if(direction) {
+    if (direction) {
       if(direction > 0) {
         SPINDLE_DIRECTION_PORT &= ~(1<<SPINDLE_DIRECTION_BIT);
       } else {
@@ -50,13 +55,8 @@ void spindle_run(int direction, uint32_t rpm)
       }
       SPINDLE_ENABLE_PORT |= 1<<SPINDLE_ENABLE_BIT;
     } else {
-      SPINDLE_ENABLE_PORT &= ~(1<<SPINDLE_ENABLE_BIT);      
+      spindle_stop();     
     }
     current_direction = direction;
   }
 }
-
-void spindle_stop()
-{
-  spindle_run(0, 0);
-}