Soft limit error bug fix.

- Soft limit errors were stuck in a feed hold without notifying the
user why it was in a hold. When resumed, the soft limit error would
kick in. Issue should be fixed to behave as intended. To automatically
hold and issue a soft limit alarm once the machine has come to a stop.

doc/log/commit_log_v1.0c.txt

@@ -1,3 +1,23 @@
+----------------
+Date: 2016-03-04
+Author: Sonny Jeon
+Subject: Applied master branch bug fixes.
+
+- Planner was under-estimating maximum speeds through straight
+junctions in certain cases. The calculations have been updated to be
+more accurate.
+
+- Strange sizeof() bug in the most recent releases. Manifested as an
+alarm upon a power up even when homing was disabled. Fixed by declaring
+sizeof() with struct types, rather than variable names, even though
+they were validated to give the same value.
+
+- Spindle speed zero should disable the spindle. Now fixed.
+
+- New configuration option for inverting certain limit pins. Handy for
+mixed NO and NC switch machines. See config.h for details.
+
+
 ----------------
 Date: 2015-11-09
 Author: Sonny Jeon

grbl/grbl.h

@@ -23,7 +23,7 @@
 
 // Grbl versioning system
 #define GRBL_VERSION "1.0c"
-#define GRBL_VERSION_BUILD "20160304"
+#define GRBL_VERSION_BUILD "20160311"
 
 // Define standard libraries used by Grbl.
 #include <avr/io.h>

grbl/limits.c

@@ -317,23 +317,22 @@ void limits_go_home(uint8_t cycle_mask)
 void limits_soft_check(float *target)
 {
   uint8_t idx;
-  uint8_t soft_limit_error = false;
   for (idx=0; idx<N_AXIS; idx++) {
    
     #ifdef HOMING_FORCE_SET_ORIGIN
       // When homing forced set origin is enabled, soft limits checks need to account for directionality.
       // NOTE: max_travel is stored as negative
       if (bit_istrue(settings.homing_dir_mask,bit(idx))) {
-        if (target[idx] < 0 || target[idx] > -settings.max_travel[idx]) { soft_limit_error = true; }
+        if (target[idx] < 0 || target[idx] > -settings.max_travel[idx]) { sys.soft_limit = true; }
       } else {
-        if (target[idx] > 0 || target[idx] < settings.max_travel[idx]) { soft_limit_error = true; }
+        if (target[idx] > 0 || target[idx] < settings.max_travel[idx]) { sys.soft_limit = true; }
       }
     #else  
       // NOTE: max_travel is stored as negative
-      if (target[idx] > 0 || target[idx] < settings.max_travel[idx]) { soft_limit_error = true; }
+      if (target[idx] > 0 || target[idx] < settings.max_travel[idx]) { sys.soft_limit = true; }
     #endif
     
-    if (soft_limit_error) {
+    if (sys.soft_limit) {
       // Force feed hold if cycle is active. All buffered blocks are guaranteed to be within 
       // workspace volume so just come to a controlled stop so position is not lost. When complete
       // enter alarm mode.

grbl/main.c

@@ -80,6 +80,7 @@ int main(void)
     sys_rt_exec_state = 0;
     sys_rt_exec_alarm = 0;
     sys.suspend = false;
+    sys.soft_limit = false;
           
     // Start Grbl main loop. Processes program inputs and executes them.
     protocol_main_loop();

grbl/protocol.c

@@ -389,7 +389,7 @@ void protocol_exec_rt_system()
       // NOTE: Bresenham algorithm variables are still maintained through both the planner and stepper
       // cycle reinitializations. The stepper path should continue exactly as if nothing has happened.   
       // NOTE: EXEC_CYCLE_STOP is set by the stepper subsystem when a cycle or feed hold completes.
-      if (sys.state & (STATE_HOLD | STATE_SAFETY_DOOR)) {
+      if ((sys.state & (STATE_HOLD | STATE_SAFETY_DOOR)) && !(sys.soft_limit)) {
         // Hold complete. Set to indicate ready to resume.  Remain in HOLD or DOOR states until user
         // has issued a resume command or reset.
         plan_cycle_reinitialize();

grbl/system.h

@@ -96,6 +96,7 @@ typedef struct {
   uint8_t abort;                 // System abort flag. Forces exit back to main loop for reset.
   uint8_t state;                 // Tracks the current state of Grbl.
   uint8_t suspend;               // System suspend bitflag variable that manages holds, cancels, and safety door.
+  uint8_t soft_limit;            // Tracks soft limit errors for the state machine (Boolean)
   uint8_t step_control;
 
   int32_t position[N_AXIS];      // Real-time machine (aka home) position vector in steps.