New compile options and inverse time bug fix.

- Apparently inverse time motion were not working for quite some time.
Goes to show how many people actually use it. The calculation was bad
and is now fixed in this update. It should now work correctly.

- `;` comment type is now supported. This is standard on LinuxCNC and
common on 3d printers. It was previously not supported due to not
existing in the NIST standard, which is out-dated.

- New compile-option to ECHO the line received. This should help users
experiencing very weird problems and help diagnose if there is
something amiss in the communication to Grbl.

- New compile-option to use the spindle direction pin D13 as a spindle
enable pin with PWM spindle speed on D11. This feature has been
requested often from the laser cutter community. Since spindle
direction isn’t really of much use, it seemed like good good trade.
Note that M4 spindle enable counter-clock-wise support is removed for
obvious reasons, while M3 and M5 still work.

grbl/config.h

@@ -251,6 +251,22 @@
 // spindle RPM output lower than this value will be set to this value.
 // #define MINIMUM_SPINDLE_PWM 5 // Default disabled. Uncomment to enable. Integer (0-255)
 
+// By default on a 328p(Uno), Grbl combines the variable spindle PWM and the enable into one pin to help 
+// preserve I/O pins. For certain setups, these may need to be separate pins. This configure option uses
+// the spindle direction pin(D13) as a separate spindle enable pin along with spindle speed PWM on pin D11. 
+// NOTE: This configure option only works with VARIABLE_SPINDLE enabled and a 328p processor (Uno). 
+// NOTE: With no direction pin, the spindle clockwise M4 g-code command will be removed. M3 and M5 still work.
+// #define USE_SPINDLE_DIR_AS_ENABLE_PIN // Default disabled. Uncomment to enable.
+
+// With this enabled, Grbl sends back an echo of the line it has received, which has been pre-parsed (spaces
+// removed, capitalized letters, no comments) and is to be immediately executed by Grbl. Echoes will not be 
+// sent upon a line buffer overflow, but should for all normal lines sent to Grbl. For example, if a user 
+// sendss the line 'g1 x1.032 y2.45 (test comment)', Grbl will echo back in the form '[echo: G1X1.032Y2.45]'.
+// NOTE: Only use this for debugging purposes!! When echoing, this takes up valuable resources and can effect
+// performance. If absolutely needed for normal operation, the serial write buffer should be greatly increased
+// to help minimize transmission waiting within the serial write protocol.
+// #define REPORT_ECHO_LINE_RECEIVED // Default disabled. Uncomment to enable.
+
 // Minimum planner junction speed. Sets the default minimum junction speed the planner plans to at
 // every buffer block junction, except for starting from rest and end of the buffer, which are always
 // zero. This value controls how fast the machine moves through junctions with no regard for acceleration
@@ -261,7 +277,8 @@
 
 // Sets the minimum feed rate the planner will allow. Any value below it will be set to this minimum
 // value. This also ensures that a planned motion always completes and accounts for any floating-point
-// round-off errors. A lower value than 1.0 mm/min may work in some cases, but we don't recommend it.
+// round-off errors. Although not recommended, a lower value than 1.0 mm/min will likely work in smaller
+// machines, perhaps to 0.1mm/min, but your success may vary based on multiple factors.
 #define MINIMUM_FEED_RATE 1.0 // (mm/min)
 
 // Number of arc generation iterations by small angle approximation before exact arc trajectory 
@@ -353,14 +370,20 @@
 // #define HARD_LIMIT_FORCE_STATE_CHECK // Default disabled. Uncomment to enable.
 
 
-// ---------------------------------------------------------------------------------------
-
-// TODO: Install compile-time option to send numeric status codes rather than strings.
-
 // ---------------------------------------------------------------------------------------
 // COMPILE-TIME ERROR CHECKING OF DEFINE VALUES:
 
+#ifndef HOMING_CYCLE_0
+  #error "Required HOMING_CYCLE_0 not defined."
+#endif
 
+#if defined(USE_SPINDLE_DIR_AS_ENABLE_PIN) && !defined(VARIABLE_SPINDLE)
+  #error "USE_SPINDLE_DIR_AS_ENABLE_PIN may only be used with VARIABLE_SPINDLE enabled"
+#endif
+
+#if defined(USE_SPINDLE_DIR_AS_ENABLE_PIN) && !defined(CPU_MAP_ATMEGA328P)
+  #error "USE_SPINDLE_DIR_AS_ENABLE_PIN may only be used with a 328p processor"
+#endif
 
 // ---------------------------------------------------------------------------------------
 

grbl/cpu_map.h

@@ -79,14 +79,22 @@
   // Define spindle enable and spindle direction output pins.
   #define SPINDLE_ENABLE_DDR    DDRB
   #define SPINDLE_ENABLE_PORT   PORTB
-  #ifdef VARIABLE_SPINDLE // Z Limit pin and spindle enabled swapped to access hardware PWM on Pin 11.  
+  // Z Limit pin and spindle PWM/enable pin swapped to access hardware PWM on Pin 11.
+  #ifdef VARIABLE_SPINDLE 
+    #ifdef USE_SPINDLE_DIR_AS_ENABLE_PIN
+      // If enabled, spindle direction pin now used as spindle enable, while PWM remains on D11.
+      #define SPINDLE_ENABLE_BIT    5  // Uno Digital Pin 13 (NOTE: D13 can't be pulled-high input due to LED.)
+    #else
       #define SPINDLE_ENABLE_BIT    3  // Uno Digital Pin 11
+    #endif
   #else
     #define SPINDLE_ENABLE_BIT    4  // Uno Digital Pin 12
   #endif
+  #ifndef USE_SPINDLE_DIR_AS_ENABLE_PIN
     #define SPINDLE_DIRECTION_DDR   DDRB
     #define SPINDLE_DIRECTION_PORT  PORTB
     #define SPINDLE_DIRECTION_BIT   5  // Uno Digital Pin 13 (NOTE: D13 can't be pulled-high input due to LED.)
+  #endif
   
   // Define flood and mist coolant enable output pins.
   // NOTE: Uno analog pins 4 and 5 are reserved for an i2c interface, and may be installed at
@@ -136,9 +144,9 @@
     #define WAVE3_REGISTER	 WGM23
     
     // NOTE: On the 328p, these must be the same as the SPINDLE_ENABLE settings.
-    #define SPINDLE_PWM_DDR	  SPINDLE_ENABLE_DDR
+    #define SPINDLE_PWM_DDR	  DDRB
-    #define SPINDLE_PWM_PORT  SPINDLE_ENABLE_PORT
+    #define SPINDLE_PWM_PORT  PORTB
-    #define SPINDLE_PWM_BIT	  SPINDLE_ENABLE_BIT // Shared with SPINDLE_ENABLE.
+    #define SPINDLE_PWM_BIT	  3    // Uno Digital Pin 11
   #endif // End of VARIABLE_SPINDLE
 
 #endif

grbl/gcode.c

@@ -281,11 +281,16 @@ uint8_t gc_execute_line(char *line)
               case 2: case 30: gc_block.modal.program_flow = PROGRAM_FLOW_COMPLETED; break; // Program end and reset 
             }
             break;
-          case 3: case 4: case 5: 
+          #ifndef USE_SPINDLE_DIR_AS_ENABLE_PIN
+            case 4: 
+          #endif
+          case 3: case 5:
             word_bit = MODAL_GROUP_M7; 
             switch(int_value) {
               case 3: gc_block.modal.spindle = SPINDLE_ENABLE_CW; break;
+              #ifndef USE_SPINDLE_DIR_AS_ENABLE_PIN
                 case 4: gc_block.modal.spindle = SPINDLE_ENABLE_CCW; break;
+              #endif
               case 5: gc_block.modal.spindle = SPINDLE_DISABLE; break;
             }
             break;            

grbl/grbl.h

@@ -23,7 +23,7 @@
 
 // Grbl versioning system
 #define GRBL_VERSION "0.9i"
-#define GRBL_VERSION_BUILD "20150315"
+#define GRBL_VERSION_BUILD "20150327"
 
 // Define standard libraries used by Grbl.
 #include <avr/io.h>

grbl/planner.c

@@ -320,7 +320,7 @@ uint8_t plan_check_full_buffer()
   // Adjust feed_rate value to mm/min depending on type of rate input (normal, inverse time, or rapids)
   // TODO: Need to distinguish a rapids vs feed move for overrides. Some flag of some sort.
   if (feed_rate < 0) { feed_rate = SOME_LARGE_VALUE; } // Scaled down to absolute max/rapids rate later
-  else if (invert_feed_rate) { feed_rate = block->millimeters/feed_rate; }
+  else if (invert_feed_rate) { feed_rate *= block->millimeters; }
   if (feed_rate < MINIMUM_FEED_RATE) { feed_rate = MINIMUM_FEED_RATE; } // Prevents step generation round-off condition.
 
   // Calculate the unit vector of the line move and the block maximum feed rate and acceleration scaled 

grbl/protocol.c

@@ -21,6 +21,11 @@
 
 #include "grbl.h"
 
+// Define different comment types for pre-parsing.
+#define COMMENT_NONE 0
+#define COMMENT_TYPE_PARENTHESES 1
+#define COMMENT_TYPE_SEMICOLON 2
+
 
 static char line[LINE_BUFFER_SIZE]; // Line to be executed. Zero-terminated.
 
@@ -33,6 +38,10 @@ static void protocol_execute_line(char *line)
   protocol_execute_realtime(); // Runtime command check point.
   if (sys.abort) { return; } // Bail to calling function upon system abort  
 
+  #ifdef REPORT_ECHO_LINE_RECEIVED
+    report_echo_line_received(line);
+  #endif
+
   if (line[0] == 0) {
     // Empty or comment line. Send status message for syncing purposes.
     report_status_message(STATUS_OK);
@@ -82,7 +91,7 @@ void protocol_main_loop()
   // Primary loop! Upon a system abort, this exits back to main() to reset the system. 
   // ---------------------------------------------------------------------------------  
   
-  uint8_t iscomment = false;
+  uint8_t comment = COMMENT_NONE;
   uint8_t char_counter = 0;
   uint8_t c;
   for (;;) {
@@ -101,14 +110,14 @@ void protocol_main_loop()
       if ((c == '\n') || (c == '\r')) { // End of line reached
         line[char_counter] = 0; // Set string termination character.
         protocol_execute_line(line); // Line is complete. Execute it!
-        iscomment = false;
+        comment = COMMENT_NONE;
         char_counter = 0;
       } else {
-        if (iscomment) {
+        if (comment != COMMENT_NONE) {
           // Throw away all comment characters
           if (c == ')') {
-            // End of comment. Resume line.
+            // End of comment. Resume line. But, not if semicolon type comment.
-            iscomment = false;
+            if (comment == COMMENT_TYPE_PARENTHESES) { comment = COMMENT_NONE; }
           }
         } else {
           if (c <= ' ') { 
@@ -121,9 +130,10 @@ void protocol_main_loop()
             // NOTE: This doesn't follow the NIST definition exactly, but is good enough for now.
             // In the future, we could simply remove the items within the comments, but retain the
             // comment control characters, so that the g-code parser can error-check it.
-            iscomment = true;
+            comment = COMMENT_TYPE_PARENTHESES;
-          // } else if (c == ';') {
+          } else if (c == ';') {
-            // Comment character to EOL NOT SUPPORTED. LinuxCNC definition. Not NIST.
+            // NOTE: ';' comment to EOL is a LinuxCNC definition. Not NIST.
+            comment = COMMENT_TYPE_SEMICOLON;
             
           // TODO: Install '%' feature 
           // } else if (c == '%') {
@@ -136,7 +146,7 @@ void protocol_main_loop()
           } else if (char_counter >= (LINE_BUFFER_SIZE-1)) {
             // Detect line buffer overflow. Report error and reset line buffer.
             report_status_message(STATUS_OVERFLOW);
-            iscomment = false;
+            comment = COMMENT_NONE;
             char_counter = 0;
           } else if (c >= 'a' && c <= 'z') { // Upcase lowercase
             line[char_counter++] = c-'a'+'A';
@@ -206,6 +216,8 @@ void protocol_execute_realtime()
         // to do what is needed before resetting, like killing the incoming stream. The 
         // same could be said about soft limits. While the position is not lost, the incoming
         // stream could be still engaged and cause a serious crash if it continues afterwards.
+        
+        // TODO: Allow status reports during a critical alarm. Still need to think about implications of this.
 //         if (sys.rt_exec_state & EXEC_STATUS_REPORT) { 
 //           report_realtime_status();
 //           bit_false_atomic(sys.rt_exec_state,EXEC_STATUS_REPORT); 

grbl/report.c

@@ -400,6 +400,15 @@ void report_build_info(char *line)
 }
 
 
+// Prints the character string line Grbl has received from the user, which has been pre-parsed,
+// and has been sent into protocol_execute_line() routine to be executed by Grbl.
+void report_echo_line_received(char *line)
+{
+  printPgmString(PSTR("[echo: ")); printString(line);
+  printPgmString(PSTR("]\r\n"));
+}
+
+
  // Prints real-time data. This function grabs a real-time snapshot of the stepper subprogram 
  // and the actual location of the CNC machine. Users may change the following function to their
  // specific needs, but the desired real-time data report must be as short as possible. This is

grbl/report.h

@@ -87,6 +87,9 @@ void report_grbl_help();
 // Prints Grbl global settings
 void report_grbl_settings();
 
+// Prints an echo of the pre-parsed line received right before execution.
+void report_echo_line_received(char *line);
+
 // Prints realtime status report
 void report_realtime_status();
 

grbl/spindle_control.c

@@ -24,16 +24,21 @@
 
 void spindle_init()
 {    
-  // On the Uno, spindle enable and PWM are shared. Other CPUs have seperate enable pin.
+  // Configure variable spindle PWM and enable pin, if requried. On the Uno, PWM and enable are
+  // combined unless configured otherwise.
   #ifdef VARIABLE_SPINDLE
     SPINDLE_PWM_DDR |= (1<<SPINDLE_PWM_BIT); // Configure as PWM output pin.
-    #ifndef CPU_MAP_ATMEGA328P 
+    #if defined(CPU_MAP_ATMEGA2560) || defined(USE_SPINDLE_DIR_AS_ENABLE_PIN)
       SPINDLE_ENABLE_DDR |= (1<<SPINDLE_ENABLE_BIT); // Configure as output pin.
     #endif     
+  // Configure no variable spindle and only enable pin.
   #else  
     SPINDLE_ENABLE_DDR |= (1<<SPINDLE_ENABLE_BIT); // Configure as output pin.
   #endif
+  
+  #ifndef USE_SPINDLE_DIR_AS_ENABLE_PIN
     SPINDLE_DIRECTION_DDR |= (1<<SPINDLE_DIRECTION_BIT); // Configure as output pin.
+  #endif
   spindle_stop();
 }
 
@@ -43,7 +48,7 @@ void spindle_stop()
   // On the Uno, spindle enable and PWM are shared. Other CPUs have seperate enable pin.
   #ifdef VARIABLE_SPINDLE
     TCCRA_REGISTER &= ~(1<<COMB_BIT); // Disable PWM. Output voltage is zero.
-    #ifndef CPU_MAP_ATMEGA328P 
+    #if defined(CPU_MAP_ATMEGA2560) || defined(USE_SPINDLE_DIR_AS_ENABLE_PIN)
       SPINDLE_ENABLE_PORT &= ~(1<<SPINDLE_ENABLE_BIT); // Set pin to low.
     #endif
   #else
@@ -61,11 +66,13 @@ void spindle_set_state(uint8_t state, float rpm)
 
   } else {
 
+    #ifndef USE_SPINDLE_DIR_AS_ENABLE_PIN
       if (state == SPINDLE_ENABLE_CW) {
         SPINDLE_DIRECTION_PORT &= ~(1<<SPINDLE_DIRECTION_BIT);
       } else {
         SPINDLE_DIRECTION_PORT |= (1<<SPINDLE_DIRECTION_BIT);
       }
+    #endif
 
     #ifdef VARIABLE_SPINDLE
       // TODO: Install the optional capability for frequency-based output for servos.
@@ -92,9 +99,11 @@ void spindle_set_state(uint8_t state, float rpm)
       #endif
       OCR_REGISTER = current_pwm; // Set PWM pin output
     
-      #ifdef CPU_MAP_ATMEGA2560 // On the Uno, spindle enable and PWM are shared.
+      // On the Uno, spindle enable and PWM are shared, unless otherwise specified.
+      #if defined(CPU_MAP_ATMEGA2560) || defined(USE_SPINDLE_DIR_AS_ENABLE_PIN) 
         SPINDLE_ENABLE_PORT |= (1<<SPINDLE_ENABLE_BIT);
       #endif
+      
     #else   
       SPINDLE_ENABLE_PORT |= (1<<SPINDLE_ENABLE_BIT);
     #endif