Tidying up parking override control implementation

[new] Added a default configuration for the parking override control
upon a reset or power-up. By default, parking is enabled, but this may
be disabled via a config.h option.

[fix] Parking override control should be checking if the command word
is passed, rather than the value.

grbl/config.h

@@ -575,8 +575,10 @@
 // These are controlled by `M56`, `M56 P1`, or `M56 Px` to enable and `M56 P0` to disable. 
 // The command is modal and will be set after a planner sync. Since it is g-code, it is 
 // executed in sync with g-code commands. It is not a real-time command.
-// NOTE: PARKING_ENABLE is required.
+// NOTE: PARKING_ENABLE is required. By default, M56 is active upon initialization. Use 
+// DEACTIVATE_PARKING_UPON_INIT to set M56 P0 as the power-up default.
 // #define ENABLE_PARKING_OVERRIDE_CONTROL   // Default disabled. Uncomment to enable
+// #define DEACTIVATE_PARKING_UPON_INIT // Default disabled. Uncomment to enable.
 
 // This option will automatically disable the laser during a feed hold by invoking a spindle stop
 // override immediately after coming to a stop. However, this also means that the laser still may

grbl/gcode.c

@@ -437,7 +437,7 @@ uint8_t gc_execute_line(char *line)
   // [8. Coolant control ]: N/A
   // [9. Override control ]: Not supported except for a Grbl-only parking motion override control.
   #ifdef ENABLE_PARKING_OVERRIDE_CONTROL
-    if (gc_block.modal.override == OVERRIDE_PARKING_MOTION) {
+    if (bit_istrue(command_words,bit(MODAL_GROUP_M9))) { // Already set as enabled in parser.
       if (bit_istrue(value_words,bit(WORD_P))) {
         if (gc_block.values.p == 0.0) { gc_block.modal.override = OVERRIDE_DISABLED; }
         bit_false(value_words,bit(WORD_P));
@@ -1102,7 +1102,13 @@ uint8_t gc_execute_line(char *line)
       gc_state.modal.coord_select = 0; // G54
       gc_state.modal.spindle = SPINDLE_DISABLE;
       gc_state.modal.coolant = COOLANT_DISABLE;
-      // gc_state.modal.override = OVERRIDE_DISABLE; // Not supported.
+      #ifdef ENABLE_PARKING_OVERRIDE_CONTROL
+        #ifdef DEACTIVATE_PARKING_UPON_INIT
+          gc_state.modal.override = OVERRIDE_DISABLED;
+        #else
+          gc_state.modal.override = OVERRIDE_PARKING_MOTION;
+        #endif
+      #endif
 
       #ifdef RESTORE_OVERRIDES_AFTER_PROGRAM_END
         sys.f_override = DEFAULT_FEED_OVERRIDE;
@@ -1148,7 +1154,7 @@ uint8_t gc_execute_line(char *line)
    group 7 = {G41, G42} cutter radius compensation (G40 is supported)
    group 8 = {G43} tool length offset (G43.1/G49 are supported)
    group 8 = {M7*} enable mist coolant (* Compile-option)
-   group 9 = {M48, M49} enable/disable feed and speed override switches
+   group 9 = {M48, M49, M56*} enable/disable override switches (* Compile-option)
    group 10 = {G98, G99} return mode canned cycles
    group 13 = {G61.1, G64} path control mode (G61 is supported)
 */

grbl/gcode.h

@@ -124,8 +124,13 @@
 #define TOOL_LENGTH_OFFSET_ENABLE_DYNAMIC 1 // G43.1
 
 // Modal Group M9: Override control
-#define OVERRIDE_DISABLED  0 // None (Default: Must be zero)
-#define OVERRIDE_PARKING_MOTION 1 // G56 (Default: Must be zero)
+#ifdef DEACTIVATE_PARKING_UPON_INIT
+  #define OVERRIDE_DISABLED  0 // (Default: Must be zero)
+  #define OVERRIDE_PARKING_MOTION 1 // M56
+#else
+  #define OVERRIDE_PARKING_MOTION 0 // M56 (Default: Must be zero)
+  #define OVERRIDE_DISABLED  1 // Parking disabled.
+#endif
 
 // Modal Group G12: Active work coordinate system
 // N/A: Stores coordinate system value (54-59) to change to.

grbl/grbl.h

@@ -23,7 +23,7 @@
 
 // Grbl versioning system
 #define GRBL_VERSION "1.1f"
-#define GRBL_VERSION_BUILD "20170128"
+#define GRBL_VERSION_BUILD "20170129"
 
 // Define standard libraries used by Grbl.
 #include <avr/io.h>

grbl/protocol.c

@@ -579,7 +579,7 @@ static void protocol_exec_rt_suspend()
             if ((bit_istrue(settings.flags,BITFLAG_HOMING_ENABLE)) &&
                             (parking_target[PARKING_AXIS] < PARKING_TARGET) &&
                             bit_isfalse(settings.flags,BITFLAG_LASER_MODE) &&
-                            !sys.override_ctrl) {
+                            (sys.override_ctrl == OVERRIDE_PARKING_MOTION)) {
             #else
             if ((bit_istrue(settings.flags,BITFLAG_HOMING_ENABLE)) &&
                             (parking_target[PARKING_AXIS] < PARKING_TARGET) &&
@@ -650,7 +650,7 @@ static void protocol_exec_rt_suspend()
               // NOTE: State is will remain DOOR, until the de-energizing and retract is complete.
               #ifdef ENABLE_PARKING_OVERRIDE_CONTROL
               if (((settings.flags & (BITFLAG_HOMING_ENABLE|BITFLAG_LASER_MODE)) == BITFLAG_HOMING_ENABLE) &&
-                  !sys.override_ctrl) {
+                   (sys.override_ctrl == OVERRIDE_PARKING_MOTION)) {
               #else
               if ((settings.flags & (BITFLAG_HOMING_ENABLE|BITFLAG_LASER_MODE)) == BITFLAG_HOMING_ENABLE) {
               #endif
@@ -689,7 +689,7 @@ static void protocol_exec_rt_suspend()
               // Execute slow plunge motion from pull-out position to resume position.
               #ifdef ENABLE_PARKING_OVERRIDE_CONTROL
               if (((settings.flags & (BITFLAG_HOMING_ENABLE|BITFLAG_LASER_MODE)) == BITFLAG_HOMING_ENABLE) &&
-                  !sys.override_ctrl) {
+                   (sys.override_ctrl == OVERRIDE_PARKING_MOTION)) {
               #else
               if ((settings.flags & (BITFLAG_HOMING_ENABLE|BITFLAG_LASER_MODE)) == BITFLAG_HOMING_ENABLE) {
               #endif

grbl/report.c

@@ -328,7 +328,7 @@ void report_gcode_modes()
   #endif
 
   #ifdef ENABLE_PARKING_OVERRIDE_CONTROL
-    if (sys.override_ctrl) { 
+    if (sys.override_ctrl == OVERRIDE_PARKING_MOTION) { 
       report_util_gcode_modes_M();
       print_uint8_base10(56);
     }