diff --git a/doc/log/commit_log_v1.1.txt b/doc/log/commit_log_v1.1.txt
index dad0699f..48a1260b 100644
--- a/doc/log/commit_log_v1.1.txt
+++ b/doc/log/commit_log_v1.1.txt
@@ -1,3 +1,15 @@
+----------------
+Date: 2016-12-18
+Author: Sonny Jeon
+Subject: Addressed optional PWM min value issue. Updated docs.
+
+- [fix] Spindle PWM minimum value had some typos. Fixed the macros to
+compile correctly. Only effects users that enable SPINDLE_MINIMUM_PWM.
+The name changed to SPINDLE_PWM_MIN_VALUE for consistency sake.
+
+- Updated the laser documentation.
+
+
 ----------------
 Date: 2016-12-12
 Author: Sonny Jeon
diff --git a/grbl/config.h b/grbl/config.h
index c4c4c4d4..66977355 100644
--- a/grbl/config.h
+++ b/grbl/config.h
@@ -454,6 +454,15 @@
 // #define RX_BUFFER_SIZE 128 // (1-254) Uncomment to override defaults in serial.h
 // #define TX_BUFFER_SIZE 100 // (1-254)
 
+// A simple software debouncing feature for hard limit switches. When enabled, the interrupt 
+// monitoring the hard limit switch pins will enable the Arduino's watchdog timer to re-check 
+// the limit pin state after a delay of about 32msec. This can help with CNC machines with 
+// problematic false triggering of their hard limit switches, but it WILL NOT fix issues with 
+// electrical interference on the signal cables from external sources. It's recommended to first
+// use shielded signal cables with their shielding connected to ground (old USB/computer cables 
+// work well and are cheap to find) and wire in a low-pass circuit into each limit pin.
+// #define ENABLE_SOFTWARE_DEBOUNCE // Default disabled. Uncomment to enable.
+
 // Configures the position after a probing cycle during Grbl's check mode. Disabled sets
 // the position to the probe target, when enabled sets the position to the start position.
 // #define SET_CHECK_MODE_PROBE_TO_START // Default disabled. Uncomment to enable.
diff --git a/grbl/grbl.h b/grbl/grbl.h
index 23b8d58c..d23fd809 100644
--- a/grbl/grbl.h
+++ b/grbl/grbl.h
@@ -23,7 +23,7 @@
 
 // Grbl versioning system
 #define GRBL_VERSION "1.1e"
-#define GRBL_VERSION_BUILD "20161218"
+#define GRBL_VERSION_BUILD "20161219"
 
 // Define standard libraries used by Grbl.
 #include <avr/io.h>
diff --git a/grbl/limits.c b/grbl/limits.c
index 7e642942..3cc2556b 100644
--- a/grbl/limits.c
+++ b/grbl/limits.c
@@ -95,29 +95,46 @@ uint8_t limits_get_state()
 // homing cycles and will not respond correctly. Upon user request or need, there may be a
 // special pinout for an e-stop, but it is generally recommended to just directly connect
 // your e-stop switch to the Arduino reset pin, since it is the most correct way to do this.
-ISR(LIMIT_INT_vect) // DEFAULT: Limit pin change interrupt process.
-{
-  // Ignore limit switches if already in an alarm state or in-process of executing an alarm.
-  // When in the alarm state, Grbl should have been reset or will force a reset, so any pending
-  // moves in the planner and serial buffers are all cleared and newly sent blocks will be
-  // locked out until a homing cycle or a kill lock command. Allows the user to disable the hard
-  // limit setting if their limits are constantly triggering after a reset and move their axes.
-  if (sys.state != STATE_ALARM) {
-    if (!(sys_rt_exec_alarm)) {
-      #ifdef HARD_LIMIT_FORCE_STATE_CHECK
-        // Check limit pin state.
+#ifndef ENABLE_SOFTWARE_DEBOUNCE
+  ISR(LIMIT_INT_vect) // DEFAULT: Limit pin change interrupt process.
+  {
+    // Ignore limit switches if already in an alarm state or in-process of executing an alarm.
+    // When in the alarm state, Grbl should have been reset or will force a reset, so any pending
+    // moves in the planner and serial buffers are all cleared and newly sent blocks will be
+    // locked out until a homing cycle or a kill lock command. Allows the user to disable the hard
+    // limit setting if their limits are constantly triggering after a reset and move their axes.
+    if (sys.state != STATE_ALARM) {
+      if (!(sys_rt_exec_alarm)) {
+        #ifdef HARD_LIMIT_FORCE_STATE_CHECK
+          // Check limit pin state.
+          if (limits_get_state()) {
+            mc_reset(); // Initiate system kill.
+            system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
+          }
+        #else
+          mc_reset(); // Initiate system kill.
+          system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
+        #endif
+      }
+    }
+  }
+#else // OPTIONAL: Software debounce limit pin routine.
+  // Upon limit pin change, enable watchdog timer to create a short delay. 
+  ISR(LIMIT_INT_vect) { if (!(WDTCSR & (1<<WDIE))) { WDTCSR |= (1<<WDIE); } }
+  ISR(WDT_vect) // Watchdog timer ISR
+  {
+    WDTCSR &= ~(1<<WDIE); // Disable watchdog timer. 
+    if (sys.state != STATE_ALARM) {  // Ignore if already in alarm state. 
+      if (!(sys_rt_exec_alarm)) {
+        // Check limit pin state. 
         if (limits_get_state()) {
           mc_reset(); // Initiate system kill.
           system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
         }
-      #else
-        mc_reset(); // Initiate system kill.
-        system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
-      #endif
+      }  
     }
   }
-}
-
+#endif
 
 // Homes the specified cycle axes, sets the machine position, and performs a pull-off motion after
 // completing. Homing is a special motion case, which involves rapid uncontrolled stops to locate
diff --git a/grbl/motion_control.c b/grbl/motion_control.c
index 4e226e41..41271063 100644
--- a/grbl/motion_control.c
+++ b/grbl/motion_control.c
@@ -359,8 +359,9 @@ void mc_reset()
     // violated, by which, all bets are off.
     if ((sys.state & (STATE_CYCLE | STATE_HOMING | STATE_JOG)) ||
     		(sys.step_control & (STEP_CONTROL_EXECUTE_HOLD | STEP_CONTROL_EXECUTE_SYS_MOTION))) {
-      if (sys.state == STATE_HOMING) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_RESET); }
-      else { system_set_exec_alarm(EXEC_ALARM_ABORT_CYCLE); }
+      if (sys.state == STATE_HOMING) { 
+        if (!sys_rt_exec_alarm) {system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_RESET); }
+      } else { system_set_exec_alarm(EXEC_ALARM_ABORT_CYCLE); }
       st_go_idle(); // Force kill steppers. Position has likely been lost.
     }
   }
diff --git a/grbl/planner.c b/grbl/planner.c
index 56212637..4839bbf4 100644
--- a/grbl/planner.c
+++ b/grbl/planner.c
@@ -331,7 +331,7 @@ uint8_t plan_buffer_line(float *target, plan_line_data_t *pl_data)
   uint8_t idx;
 
   // Copy position data based on type of motion being planned.
-    if (block->condition & PL_COND_FLAG_SYSTEM_MOTION) { 
+  if (block->condition & PL_COND_FLAG_SYSTEM_MOTION) { 
     #ifdef COREXY
       position_steps[X_AXIS] = system_convert_corexy_to_x_axis_steps(sys_position);
       position_steps[Y_AXIS] = system_convert_corexy_to_y_axis_steps(sys_position);
diff --git a/grbl/protocol.c b/grbl/protocol.c
index dda09a87..2d5b8d1c 100644
--- a/grbl/protocol.c
+++ b/grbl/protocol.c
@@ -234,7 +234,7 @@ void protocol_exec_rt_system()
         // lost, continued streaming could cause a serious crash if by chance it gets executed.
       } while (bit_isfalse(sys_rt_exec_state,EXEC_RESET));
     }
-    system_clear_exec_alarm_flag(0xFF); // Clear all alarm flags
+    system_clear_exec_alarm(); // Clear alarm
   }
 
   rt_exec = sys_rt_exec_state; // Copy volatile sys_rt_exec_state.
diff --git a/grbl/report.c b/grbl/report.c
index 54a53fd6..7dd26afd 100644
--- a/grbl/report.c
+++ b/grbl/report.c
@@ -109,7 +109,6 @@ static void report_util_float_setting(uint8_t n, float val, uint8_t n_decimal) {
 // operation. Errors events can originate from the g-code parser, settings module, or asynchronously
 // from a critical error, such as a triggered hard limit. Interface should always monitor for these
 // responses.
-// NOTE: In REPORT_GUI_MODE, all error codes are greater than zero.
 void report_status_message(uint8_t status_code)
 {
   switch(status_code) {
@@ -123,7 +122,7 @@ void report_status_message(uint8_t status_code)
 }
 
 // Prints alarm messages.
-void report_alarm_message(int8_t alarm_code)
+void report_alarm_message(uint8_t alarm_code)
 {
   printPgmString(PSTR("ALARM:"));
   print_uint8_base10(alarm_code);
diff --git a/grbl/report.h b/grbl/report.h
index 6488ed1e..cdeacfa9 100644
--- a/grbl/report.h
+++ b/grbl/report.h
@@ -86,7 +86,7 @@
 void report_status_message(uint8_t status_code);
 
 // Prints system alarm messages.
-void report_alarm_message(int8_t alarm_code);
+void report_alarm_message(uint8_t alarm_code);
 
 // Prints miscellaneous feedback messages.
 void report_feedback_message(uint8_t message_code);
diff --git a/grbl/system.c b/grbl/system.c
index 14f56fd6..d1665fff 100644
--- a/grbl/system.c
+++ b/grbl/system.c
@@ -371,10 +371,10 @@ void system_set_exec_alarm(uint8_t code) {
   SREG = sreg;
 }
 
-void system_clear_exec_alarm_flag(uint8_t mask) {
+void system_clear_exec_alarm() {
   uint8_t sreg = SREG;
   cli();
-  sys_rt_exec_alarm &= ~(mask);
+  sys_rt_exec_alarm = 0;
   SREG = sreg;
 }
 
diff --git a/grbl/system.h b/grbl/system.h
index a4ca8185..0cbea6b6 100644
--- a/grbl/system.h
+++ b/grbl/system.h
@@ -195,7 +195,7 @@ uint8_t system_check_travel_limits(float *target);
 void system_set_exec_state_flag(uint8_t mask);
 void system_clear_exec_state_flag(uint8_t mask);
 void system_set_exec_alarm(uint8_t code);
-void system_clear_exec_alarm_flag(uint8_t mask);
+void system_clear_exec_alarm();
 void system_set_exec_motion_override_flag(uint8_t mask);
 void system_set_exec_accessory_override_flag(uint8_t mask);
 void system_clear_exec_motion_overrides();