v1.0 Beta Release.

- Tons of new stuff in this release, which is fairly stable and well
tested. However, much more is coming soon!

- Real-time parking motion with safety door. When this compile option
is enabled, an opened safety door will cause Grbl to automatically feed
hold, retract, de-energize the spindle/coolant, and parks near Z max.
After the door is closed and resume is commanded, this reverses and the
program continues as if nothing happened. This is also highly
configurable. See config.h for details.

- New spindle max and min rpm ‘$’ settings! This has been requested
often. Grbl will output 5V when commanded to turn on the spindle at its
max rpm, and 0.02V with min rpm. The voltage and the rpm range are
linear to each other. This should help users tweak their settings to
get close to true rpm’s.

- If the new max rpm ‘$’ setting is set = 0 or less than min rpm, the
spindle speed PWM pin will act like a regular on/off spindle enable
pin. On pin D11.

- BEWARE: Your old EEPROM settings will be wiped! The new spindle rpm
settings require a new settings version, so Grbl will automatically
wipe and restore the EEPROM with the new defaults.

- Control pin can now be inverted individually with a
CONTROL_INVERT_MASK in the cpu_map header file. Not typical for users
to need this, but handy to have.

- Fixed bug when Grbl receive too many characters in a line and
overflows. Previously it would respond with an error per overflow
character and another acknowledge upon an EOL character. This broke the
streaming protocol. Now fixed to only respond with an error after an
EOL character.

- Fixed a bug with the safety door during an ALARM mode. You now can’t
home or unlock the axes until the safety door has been closed. This is
for safety reasons (obviously.)

- Tweaked some the Mega2560 cpu_map settings . Increased segment buffer
size and fixed the spindle PWM settings to output at a higher PWM
frequency.

- Generalized the delay function used by G4 delay for use by parking
motion. Allows non-blocking status reports and real-time control during
re-energizing of the spindle and coolant.

- Added spindle rpm max and min defaults to default.h files.

- Added a new print float for rpm values.

grbl/planner.h

@@ -32,6 +32,9 @@
   #endif
 #endif
 
+#define PLAN_OK true
+#define PLAN_EMPTY_BLOCK false
+
 // This struct stores a linear movement of a g-code block motion with its critical "nominal" values
 // are as specified in the source g-code. 
 typedef struct {
@@ -39,9 +42,10 @@ typedef struct {
   // NOTE: Used by stepper algorithm to execute the block correctly. Do not alter these values.
   uint8_t direction_bits;    // The direction bit set for this block (refers to *_DIRECTION_BIT in config.h)
   uint32_t steps[N_AXIS];    // Step count along each axis
-  uint32_t step_event_count; // The maximum step axis count and number of steps required to complete this block. 
+  uint32_t step_event_count; // The maximum step axis count and number of steps required to complete this block.
 
-  // Fields used by the motion planner to manage acceleration
+  // Fields used by the motion planner to manage acceleration. Some of these values may be updated
+  // by the stepper module during execution of special motion cases for replanning purposes.
   float entry_speed_sqr;         // The current planned entry speed at block junction in (mm/min)^2
   float max_entry_speed_sqr;     // Maximum allowable entry speed based on the minimum of junction limit and 
                                  //   neighboring nominal speeds with overrides in (mm/min)^2
@@ -64,15 +68,18 @@ void plan_reset();
 // in millimeters. Feed rate specifies the speed of the motion. If feed rate is inverted, the feed
 // rate is taken to mean "frequency" and would complete the operation in 1/feed_rate minutes.
 #ifdef USE_LINE_NUMBERS
-  void plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate, int32_t line_number);
+  uint8_t plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate, uint8_t is_parking_motion, int32_t line_number);
 #else
-  void plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate);
+  uint8_t plan_buffer_line(float *target, float feed_rate, uint8_t invert_feed_rate, uint8_t is_parking_motion);
 #endif
 
 // Called when the current block is no longer needed. Discards the block and makes the memory
 // availible for new blocks.
 void plan_discard_current_block();
 
+// Gets the planner block for the parking special motion case. Parking uses the always available buffer head.
+plan_block_t *plan_get_parking_block();
+
 // Gets the current block. Returns NULL if buffer empty
 plan_block_t *plan_get_current_block();