Пример #1
0
bool st_get_next_segment_up3d(segment_up3d_t** ppseg)
{
  //auto prepare new segment(s) if segment buffer empty
  if (segment_buffer_head == segment_buffer_tail)
    st_prep_buffer();

  //exit if no segments found
  if (segment_buffer_head == segment_buffer_tail)
    return false;

  *ppseg = &segment_buffer[segment_buffer_tail];

  // Segment is complete. Advance segment indexing.
  if ( ++segment_buffer_tail == SEGMENT_BUFFER_SIZE) { segment_buffer_tail = 0; }

  return true;
}
Пример #2
0
// Plans and executes the single special motion case for parking. Independent of main planner buffer.
// NOTE: Uses the always free planner ring buffer head to store motion parameters for execution.
void mc_parking_motion(float *parking_target, plan_line_data_t *pl_data)
{
  if (sys.abort) { return; } // Block during abort.

  uint8_t plan_status = plan_buffer_line(parking_target, pl_data);

  if (plan_status) {
		bit_true(sys.step_control, STEP_CONTROL_EXECUTE_SYS_MOTION);
		bit_false(sys.step_control, STEP_CONTROL_END_MOTION); // Allow parking motion to execute, if feed hold is active.
    st_parking_setup_buffer(); // Setup step segment buffer for special parking motion case
		st_prep_buffer();
		st_wake_up();
		do {
			protocol_exec_rt_system();
			if (sys.abort) { return; }
		} while (sys.step_control & STEP_CONTROL_EXECUTE_SYS_MOTION);
		st_parking_restore_buffer(); // Restore step segment buffer to normal run state.
	} else {
    bit_false(sys.step_control, STEP_CONTROL_EXECUTE_SYS_MOTION);
		protocol_exec_rt_system();
  }

}
Пример #3
0
// 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
// the trigger point of the limit switches. The rapid stops are handled by a system level axis lock 
// mask, which prevents the stepper algorithm from executing step pulses. Homing motions typically 
// circumvent the processes for executing motions in normal operation.
// NOTE: Only the abort realtime command can interrupt this process.
// TODO: Move limit pin-specific calls to a general function for portability.
void limits_go_home(uint8_t cycle_mask) 
{
  if (sys.abort) { return; } // Block if system reset has been issued.

  // Initialize
  uint8_t n_cycle = (2*N_HOMING_LOCATE_CYCLE+1);
  uint8_t step_pin[N_AXIS];
  float target[N_AXIS];
  float max_travel = 0.0;
  uint8_t idx;
  for (idx=0; idx<N_AXIS; idx++) {  
    // Initialize step pin masks
    step_pin[idx] = get_step_pin_mask(idx);
    #ifdef COREXY    
      if ((idx==A_MOTOR)||(idx==B_MOTOR)) { step_pin[idx] = (get_step_pin_mask(X_AXIS)|get_step_pin_mask(Y_AXIS)); } 
    #endif

    if (bit_istrue(cycle_mask,bit(idx))) { 
      // Set target based on max_travel setting. Ensure homing switches engaged with search scalar.
      // NOTE: settings.max_travel[] is stored as a negative value.
      max_travel = max(max_travel,(-HOMING_AXIS_SEARCH_SCALAR)*settings.max_travel[idx]);
    }
  }

  // Set search mode with approach at seek rate to quickly engage the specified cycle_mask limit switches.
  bool approach = true;
  float homing_rate = settings.homing_seek_rate;

  uint8_t limit_state, axislock, n_active_axis;
  do {

    system_convert_array_steps_to_mpos(target,sys.position);

    // Initialize and declare variables needed for homing routine.
    axislock = 0;
    n_active_axis = 0;
    for (idx=0; idx<N_AXIS; idx++) {
      // Set target location for active axes and setup computation for homing rate.
      if (bit_istrue(cycle_mask,bit(idx))) {
        n_active_axis++;
        sys.position[idx] = 0;
        // Set target direction based on cycle mask and homing cycle approach state.
        // NOTE: This happens to compile smaller than any other implementation tried.
        if (bit_istrue(settings.homing_dir_mask,bit(idx))) {
          if (approach) { target[idx] = -max_travel; }
          else { target[idx] = max_travel; }
        } else { 
          if (approach) { target[idx] = max_travel; }
          else { target[idx] = -max_travel; }
        }        
        // Apply axislock to the step port pins active in this cycle.
        axislock |= step_pin[idx];
      }

    }
    homing_rate *= sqrt(n_active_axis); // [sqrt(N_AXIS)] Adjust so individual axes all move at homing rate.
    sys.homing_axis_lock = axislock;

    plan_sync_position(); // Sync planner position to current machine position.
    
    // Perform homing cycle. Planner buffer should be empty, as required to initiate the homing cycle.
    #ifdef USE_LINE_NUMBERS
      plan_buffer_line(target, homing_rate, false, false, HOMING_CYCLE_LINE_NUMBER); // Bypass mc_line(). Directly plan homing motion.
    #else
      plan_buffer_line(target, homing_rate, false, false); // Bypass mc_line(). Directly plan homing motion.
    #endif
    
    st_prep_buffer(); // Prep and fill segment buffer from newly planned block.
    st_wake_up(); // Initiate motion
    do {
      if (approach) {
        // Check limit state. Lock out cycle axes when they change.
        limit_state = limits_get_state();
        for (idx=0; idx<N_AXIS; idx++) {
          if (axislock & step_pin[idx]) {
            if (limit_state & (1 << idx)) { axislock &= ~(step_pin[idx]); }
          }
        }
        sys.homing_axis_lock = axislock;
      }

      st_prep_buffer(); // Check and prep segment buffer. NOTE: Should take no longer than 200us.

      // Exit routines: No time to run protocol_execute_realtime() in this loop.
      if (sys_rt_exec_state & (EXEC_SAFETY_DOOR | EXEC_RESET | EXEC_CYCLE_STOP)) {
        // Homing failure: Limit switches are still engaged after pull-off motion
        if ( (sys_rt_exec_state & (EXEC_SAFETY_DOOR | EXEC_RESET)) ||  // Safety door or reset issued
           (!approach && (limits_get_state() & cycle_mask)) ||  // Limit switch still engaged after pull-off motion
           ( approach && (sys_rt_exec_state & EXEC_CYCLE_STOP)) ) { // Limit switch not found during approach.
          mc_reset(); // Stop motors, if they are running.
          protocol_execute_realtime();
          return;
        } else {
          // Pull-off motion complete. Disable CYCLE_STOP from executing.
          system_clear_exec_state_flag(EXEC_CYCLE_STOP);
          break;
        } 
      }

    } while (STEP_MASK & axislock);

    st_reset(); // Immediately force kill steppers and reset step segment buffer.
    plan_reset(); // Reset planner buffer to zero planner current position and to clear previous motions.

    delay_ms(settings.homing_debounce_delay); // Delay to allow transient dynamics to dissipate.

    // Reverse direction and reset homing rate for locate cycle(s).
    approach = !approach;

    // After first cycle, homing enters locating phase. Shorten search to pull-off distance.
    if (approach) { 
      max_travel = settings.homing_pulloff*HOMING_AXIS_LOCATE_SCALAR; 
      homing_rate = settings.homing_feed_rate;
    } else {
      max_travel = settings.homing_pulloff;    
      homing_rate = settings.homing_seek_rate;
    }
    
  } while (n_cycle-- > 0);
      
  // The active cycle axes should now be homed and machine limits have been located. By 
  // default, Grbl defines machine space as all negative, as do most CNCs. Since limit switches
  // can be on either side of an axes, check and set axes machine zero appropriately. Also,
  // set up pull-off maneuver from axes limit switches that have been homed. This provides
  // some initial clearance off the switches and should also help prevent them from falsely
  // triggering when hard limits are enabled or when more than one axes shares a limit pin.
  #ifdef COREXY
    int32_t off_axis_position = 0;
  #endif
  int32_t set_axis_position;
  // Set machine positions for homed limit switches. Don't update non-homed axes.
  for (idx=0; idx<N_AXIS; idx++) {
    // NOTE: settings.max_travel[] is stored as a negative value.
    if (cycle_mask & bit(idx)) {
      #ifdef HOMING_FORCE_SET_ORIGIN
        set_axis_position = 0;
      #else 
        if ( bit_istrue(settings.homing_dir_mask,bit(idx)) ) {
          set_axis_position = lround((settings.max_travel[idx]+settings.homing_pulloff)*settings.steps_per_mm[idx]);
        } else {
          set_axis_position = lround(-settings.homing_pulloff*settings.steps_per_mm[idx]);
        }
      #endif
      
      #ifdef COREXY
        if (idx==X_AXIS) { 
          off_axis_position = (sys.position[B_MOTOR] - sys.position[A_MOTOR])/2;
          sys.position[A_MOTOR] = set_axis_position - off_axis_position;
          sys.position[B_MOTOR] = set_axis_position + off_axis_position;          
        } else if (idx==Y_AXIS) {
          off_axis_position = (sys.position[A_MOTOR] + sys.position[B_MOTOR])/2;
          sys.position[A_MOTOR] = off_axis_position - set_axis_position;
          sys.position[B_MOTOR] = off_axis_position + set_axis_position;
        } else {
          sys.position[idx] = set_axis_position;
        }        
      #else 
        sys.position[idx] = set_axis_position;
      #endif

    }
  }
  plan_sync_position(); // Sync planner position to homed machine position.
    
  // sys.state = STATE_HOMING; // Ensure system state set as homing before returning. 
}
Пример #4
0
// 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
// the trigger point of the limit switches. The rapid stops are handled by a system level axis lock 
// mask, which prevents the stepper algorithm from executing step pulses. Homing motions typically 
// circumvent the processes for executing motions in normal operation.
// NOTE: Only the abort runtime command can interrupt this process.
void limits_go_home(uint8_t cycle_mask) 
{
  if (sys.abort) { return; } // Block if system reset has been issued.

  // Initialize homing in search mode to quickly engage the specified cycle_mask limit switches.
  bool approach = true;
  float homing_rate = settings.homing_seek_rate;
  uint8_t invert_pin, idx;
  uint8_t n_cycle = (2*N_HOMING_LOCATE_CYCLE+1);  ///***5
  float target[N_AXIS];
  
  uint8_t limit_pin[N_AXIS], step_pin[N_AXIS];
  float max_travel = 0.0;
  for (idx=0; idx<N_AXIS; idx++) {  
    // Initialize limit and step pin masks
    limit_pin[idx] = get_limit_pin_mask(idx);    ///////****get the Pin  of  limit min x, y ,z ,  Limit OK
    step_pin[idx] = get_step_pin_mask(idx);       ///////****get the Pin  of  limit min x, y ,z   now I let it 0, 1, 2

    // Determine travel distance to the furthest homing switch based on user max travel settings.
    // NOTE: settings.max_travel[] is stored as a negative value.
    if (max_travel > settings.max_travel[idx]) { max_travel = settings.max_travel[idx]; }
  }
  max_travel *= -HOMING_AXIS_SEARCH_SCALAR; // Ensure homing switches engaged by over-estimating max travel.
  
  plan_reset(); // Reset planner buffer to zero planner current position and to clear previous motions.
  
  do {
    // Initialize invert_pin boolean based on approach and invert pin user setting.
    if (bit_isfalse(settings.flags,BITFLAG_INVERT_LIMIT_PINS)) { invert_pin = approach; }
    else { invert_pin = !approach; }

    // Initialize and declare variables needed for homing routine.
    uint8_t n_active_axis = 0;
    uint8_t axislock = 0;
        
    for (idx=0; idx<N_AXIS; idx++) {
      // Set target location for active axes and setup computation for homing rate.
      if (bit_istrue(cycle_mask,bit(idx))) { 
        n_active_axis++;
        if (!approach) { target[idx] = -max_travel; }
        else { target[idx] = max_travel; }
      } else {
        target[idx] = 0.0;
      }


      // Set target direction based on cycle mask
      if (bit_istrue(settings.homing_dir_mask,bit(idx))) { target[idx] = -target[idx]; }
      
      // Apply axislock to the step port pins active in this cycle.
      if (bit_istrue(cycle_mask,bit(idx))) { axislock |= step_pin[idx]; }
    }      
    homing_rate *= sqrt(n_active_axis); // [sqrt(N_AXIS)] Adjust so individual axes all move at homing rate.
    sys.homing_axis_lock = axislock;
  
    // Perform homing cycle. Planner buffer should be empty, as required to initiate the homing cycle.
    uint8_t limit_state;
    
    #ifdef USE_LINE_NUMBERS
      plan_buffer_line(target, homing_rate, false, HOMING_CYCLE_LINE_NUMBER); // Bypass mc_line(). Directly plan homing motion.
    #else
      plan_buffer_line(target, homing_rate, false); // Bypass mc_line(). Directly plan homing motion.
    #endif
    
    st_prep_buffer(); // Prep and fill segment buffer from newly planned block.
    st_wake_up(); // Initiate motion
    do {
      // Check limit state. Lock out cycle axes when they change.
	  /////////////////########################################***********
#if MotherBoard==3 /////**MB==3  
#ifdef limit_int_style
		  limit_state = LIMIT_PIN;
	      if (invert_pin) { limit_state ^= LIMIT_MASK; }
#else
	  //************Get Limit Pin State.	 PiBot get limit/endstop mask same with the step mask.
#if LIMIT_MAX_OPEN
		  if(isXMinEndstopHit()) { limit_state^= MASK(X_LIMIT_BIT);}   ////***read X_endstop then write into limite_state
		  if(isYMinEndstopHit()) { limit_state^= MASK(Y_LIMIT_BIT);} 
		  if(isZMinEndstopHit()) { limit_state^= MASK(Z_LIMIT_BIT);}   ////*****add MAX limit
		  if(isXMaxEndstopHit()) { limit_state^= MASK(X_LIMIT_MAX_BIT);}   ////***read X_endstop then write into limite_state
		  if(isYMaxEndstopHit()) { limit_state^= MASK(Y_LIMIT_MAX_BIT);} 
		  if(isZMaxEndstopHit()) { limit_state^= MASK(Z_LIMIT_MAX_BIT);}   ////*****add MAX limit
#else
		  if(isXMinEndstopHit()) { limit_state^= MASK(X_MASK);} ////***read X_endstop then write into limite_state
		  if(isYMinEndstopHit()) { limit_state^= MASK(Y_MASK);} 
		  if(isZMinEndstopHit()) { limit_state^= MASK(Z_MASK);} ////*****add MAX limit
#endif
#endif
#else  /////**MB!=3   ////////#################################################
      limit_state = LIMIT_PIN;
      if (invert_pin) { limit_state ^= LIMIT_MASK; }
#endif   /////**MB==3
	  /////////////////////////////#####################################

      for (idx=0; idx<N_AXIS; idx++) {
        if (axislock & step_pin[idx]) {
          if (limit_state & limit_pin[idx]) { axislock &= ~(step_pin[idx]); }
        }
      }
      sys.homing_axis_lock = axislock;
      st_prep_buffer(); // Check and prep segment buffer. NOTE: Should take no longer than 200us.
      // Check only for user reset. No time to run protocol_execute_runtime() in this loop.
      if (sys.execute & EXEC_RESET) { protocol_execute_runtime(); return; }
    } while (STEP_MASK & axislock);
    
    st_reset(); // Immediately force kill steppers and reset step segment buffer.
    plan_reset(); // Reset planner buffer. Zero planner positions. Ensure homing motion is cleared.

    delay_ms(settings.homing_debounce_delay); // Delay to allow transient dynamics to dissipate.

    // Reverse direction and reset homing rate for locate cycle(s).
    homing_rate = settings.homing_feed_rate;
    approach = !approach;
    
  } while (n_cycle-- > 0);
    
  // The active cycle axes should now be homed and machine limits have been located. By 
  // default, grbl defines machine space as all negative, as do most CNCs. Since limit switches
  // can be on either side of an axes, check and set axes machine zero appropriately. Also,
  // set up pull-off maneuver from axes limit switches that have been homed. This provides
  // some initial clearance off the switches and should also help prevent them from falsely
  // triggering when hard limits are enabled or when more than one axes shares a limit pin.
  for (idx=0; idx<N_AXIS; idx++) {
    // Set up pull off targets and machine positions for limit switches homed in the negative
    // direction, rather than the traditional positive. Leave non-homed positions as zero and
    // do not move them.
    // NOTE: settings.max_travel[] is stored as a negative value.
    if (cycle_mask & bit(idx)) {
    
      #ifdef HOMING_FORCE_SET_ORIGIN
        sys.position[idx] = 0;  // Set axis homed location as axis origin
        target[idx] = settings.homing_pulloff;  
        if ( bit_isfalse(settings.homing_dir_mask,bit(idx)) ) { target[idx] = -target[idx]; }     
      #else
        if ( bit_istrue(settings.homing_dir_mask,bit(idx)) ) {
          target[idx] = settings.homing_pulloff+settings.max_travel[idx];
          sys.position[idx] = lround(settings.max_travel[idx]*settings.steps_per_mm[idx]);
        } else {
          target[idx] = -settings.homing_pulloff;
          sys.position[idx] = 0;
        }
      #endif
      
    } else { // Non-active cycle axis. Set target to not move during pull-off. 
      target[idx] = (float)sys.position[idx]/settings.steps_per_mm[idx];
    }
  }
  plan_sync_position(); // Sync planner position to current machine position for pull-off move.
  
  #ifdef USE_LINE_NUMBERS
    plan_buffer_line(target, settings.homing_seek_rate, false, HOMING_CYCLE_LINE_NUMBER); // Bypass mc_line(). Directly plan motion.
  #else
    plan_buffer_line(target, settings.homing_seek_rate, false); // Bypass mc_line(). Directly plan motion.
  #endif
  
  // Initiate pull-off using main motion control routines. 
  // TODO : Clean up state routines so that this motion still shows homing state.
  sys.state = STATE_QUEUED;
  bit_true_atomic(sys.execute, EXEC_CYCLE_START);
  protocol_execute_runtime();
  protocol_buffer_synchronize(); // Complete pull-off motion.
  
  // Set system state to homing before returning. 
  sys.state = STATE_HOMING; 
}
Пример #5
0
// Executes run-time commands, when required. This is called from various check points in the main
// program, primarily where there may be a while loop waiting for a buffer to clear space or any
// point where the execution time from the last check point may be more than a fraction of a second.
// This is a way to execute realtime commands asynchronously (aka multitasking) with grbl's g-code
// parsing and planning functions. This function also serves as an interface for the interrupts to 
// set the system realtime flags, where only the main program handles them, removing the need to
// define more computationally-expensive volatile variables. This also provides a controlled way to 
// execute certain tasks without having two or more instances of the same task, such as the planner
// recalculating the buffer upon a feedhold or override.
// NOTE: The sys_rt_exec_state variable flags are set by any process, step or serial interrupts, pinouts,
// limit switches, or the main program.
void protocol_execute_realtime()
{
  uint8_t rt_exec; // Temp variable to avoid calling volatile multiple times.

  do { // If system is suspended, suspend loop restarts here.
    
  // Check and execute alarms. 
  rt_exec = sys_rt_exec_alarm; // Copy volatile sys_rt_exec_alarm.
  if (rt_exec) { // Enter only if any bit flag is true
    // System alarm. Everything has shutdown by something that has gone severely wrong. Report
    // the source of the error to the user. If critical, Grbl disables by entering an infinite
    // loop until system reset/abort.
    sys.state = STATE_ALARM; // Set system alarm state
    if (rt_exec & EXEC_ALARM_HARD_LIMIT) {
      report_alarm_message(ALARM_HARD_LIMIT_ERROR); 
    } else if (rt_exec & EXEC_ALARM_SOFT_LIMIT) {
      report_alarm_message(ALARM_SOFT_LIMIT_ERROR);
    } else if (rt_exec & EXEC_ALARM_ABORT_CYCLE) {      
      report_alarm_message(ALARM_ABORT_CYCLE);
    } else if (rt_exec & EXEC_ALARM_PROBE_FAIL) {
      report_alarm_message(ALARM_PROBE_FAIL);
    } else if (rt_exec & EXEC_ALARM_HOMING_FAIL) {
      report_alarm_message(ALARM_HOMING_FAIL);
    }
    // Halt everything upon a critical event flag. Currently hard and soft limits flag this.
    if (rt_exec & EXEC_CRITICAL_EVENT) {
      report_feedback_message(MESSAGE_CRITICAL_EVENT);
      bit_false_atomic(sys_rt_exec_state,EXEC_RESET); // Disable any existing reset
      do { 
        // Nothing. Block EVERYTHING until user issues reset or power cycles. Hard limits
        // typically occur while unattended or not paying attention. Gives the user time
        // 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); 
//         }
      } while (bit_isfalse(sys_rt_exec_state,EXEC_RESET));
    }
    bit_false_atomic(sys_rt_exec_alarm,0xFF); // Clear all alarm flags
  }
  
  // Check amd execute realtime commands
  rt_exec = sys_rt_exec_state; // Copy volatile sys_rt_exec_state.
  if (rt_exec) { // Enter only if any bit flag is true
  
    // Execute system abort. 
    if (rt_exec & EXEC_RESET) {
      sys.abort = true;  // Only place this is set true.
      return; // Nothing else to do but exit.
    }
    
    // Execute and serial print status
    if (rt_exec & EXEC_STATUS_REPORT) { 
      report_realtime_status();
      bit_false_atomic(sys_rt_exec_state,EXEC_STATUS_REPORT);
    }
  
    // Execute hold states.
    // NOTE: The math involved to calculate the hold should be low enough for most, if not all, 
    // operational scenarios. Once hold is initiated, the system enters a suspend state to block
    // all main program processes until either reset or resumed.
    if (rt_exec & (EXEC_MOTION_CANCEL | EXEC_FEED_HOLD | EXEC_SAFETY_DOOR)) {
      
      // TODO: CHECK MODE? How to handle this? Likely nothing, since it only works when IDLE and then resets Grbl.
                
      // State check for allowable states for hold methods.
      if ((sys.state == STATE_IDLE) || (sys.state & (STATE_CYCLE | STATE_HOMING | STATE_MOTION_CANCEL | STATE_HOLD | STATE_SAFETY_DOOR))) {

        // If in CYCLE state, all hold states immediately initiate a motion HOLD.
        if (sys.state == STATE_CYCLE) {
          st_update_plan_block_parameters(); // Notify stepper module to recompute for hold deceleration.
          sys.suspend = SUSPEND_ENABLE_HOLD; // Initiate holding cycle with flag.
        }
        // If IDLE, Grbl is not in motion. Simply indicate suspend ready state.
        if (sys.state == STATE_IDLE) { sys.suspend = SUSPEND_ENABLE_READY; }
        
        // Execute and flag a motion cancel with deceleration and return to idle. Used primarily by probing cycle
        // to halt and cancel the remainder of the motion.
        if (rt_exec & EXEC_MOTION_CANCEL) {
          // MOTION_CANCEL only occurs during a CYCLE, but a HOLD and SAFETY_DOOR may been initiated beforehand
          // to hold the CYCLE. If so, only flag that motion cancel is complete.
          if (sys.state == STATE_CYCLE) { sys.state = STATE_MOTION_CANCEL; }
          sys.suspend |= SUSPEND_MOTION_CANCEL; // Indicate motion cancel when resuming. Special motion complete.
        }
    
        // Execute a feed hold with deceleration, only during cycle.
        if (rt_exec & EXEC_FEED_HOLD) {
          // Block SAFETY_DOOR state from prematurely changing back to HOLD.
          if (bit_isfalse(sys.state,STATE_SAFETY_DOOR)) { sys.state = STATE_HOLD; }
        }
  
        // Execute a safety door stop with a feed hold, only during a cycle, and disable spindle/coolant.
        // NOTE: Safety door differs from feed holds by stopping everything no matter state, disables powered
        // devices (spindle/coolant), and blocks resuming until switch is re-engaged. The power-down is 
        // executed here, if IDLE, or when the CYCLE completes via the EXEC_CYCLE_STOP flag.
        if (rt_exec & EXEC_SAFETY_DOOR) {
          report_feedback_message(MESSAGE_SAFETY_DOOR_AJAR); 
          // If already in active, ready-to-resume HOLD, set CYCLE_STOP flag to force de-energize.
          // NOTE: Only temporarily sets the 'rt_exec' variable, not the volatile 'rt_exec_state' variable.
          if (sys.suspend & SUSPEND_ENABLE_READY) { bit_true(rt_exec,EXEC_CYCLE_STOP); }
          sys.suspend |= SUSPEND_ENERGIZE;
          sys.state = STATE_SAFETY_DOOR;
        }
         
      }
      bit_false_atomic(sys_rt_exec_state,(EXEC_MOTION_CANCEL | EXEC_FEED_HOLD | EXEC_SAFETY_DOOR));      
    }
          
    // Execute a cycle start by starting the stepper interrupt to begin executing the blocks in queue.
    if (rt_exec & EXEC_CYCLE_START) {
      // Block if called at same time as the hold commands: feed hold, motion cancel, and safety door.
      // Ensures auto-cycle-start doesn't resume a hold without an explicit user-input.
      if (!(rt_exec & (EXEC_FEED_HOLD | EXEC_MOTION_CANCEL | EXEC_SAFETY_DOOR))) { 
        // Cycle start only when IDLE or when a hold is complete and ready to resume.
        // NOTE: SAFETY_DOOR is implicitly blocked. It reverts to HOLD when the door is closed.
        if ((sys.state == STATE_IDLE) || ((sys.state & (STATE_HOLD | STATE_MOTION_CANCEL)) && (sys.suspend & SUSPEND_ENABLE_READY))) {
          // Re-energize powered components, if disabled by SAFETY_DOOR.
          if (sys.suspend & SUSPEND_ENERGIZE) { 
            // Delayed Tasks: Restart spindle and coolant, delay to power-up, then resume cycle.
            if (gc_state.modal.spindle != SPINDLE_DISABLE) { 
              spindle_set_state(gc_state.modal.spindle, gc_state.spindle_speed); 
              delay_ms(SAFETY_DOOR_SPINDLE_DELAY); // TODO: Blocking function call. Need a non-blocking one eventually.
            }
            if (gc_state.modal.coolant != COOLANT_DISABLE) { 
              coolant_set_state(gc_state.modal.coolant); 
              delay_ms(SAFETY_DOOR_COOLANT_DELAY); // TODO: Blocking function call. Need a non-blocking one eventually.
            }
            // TODO: Install return to pre-park position.
          }
          // Start cycle only if queued motions exist in planner buffer and the motion is not canceled.
          if (plan_get_current_block() && bit_isfalse(sys.suspend,SUSPEND_MOTION_CANCEL)) {
            sys.state = STATE_CYCLE;
            st_prep_buffer(); // Initialize step segment buffer before beginning cycle.
            st_wake_up();
          } else { // Otherwise, do nothing. Set and resume IDLE state.
            sys.state = STATE_IDLE;
          }
          sys.suspend = SUSPEND_DISABLE; // Break suspend state.
        }
      }    
      bit_false_atomic(sys_rt_exec_state,EXEC_CYCLE_START);
    }
    
    // Reinitializes the cycle plan and stepper system after a feed hold for a resume. Called by 
    // realtime command execution in the main program, ensuring that the planner re-plans safely.
    // 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 (rt_exec & EXEC_CYCLE_STOP) {
      if (sys.state & (STATE_HOLD | STATE_SAFETY_DOOR)) {
        // Hold complete. Set to indicate ready to resume.  Remain in HOLD or DOOR states until user
        // has issued a resume command or reset.
        if (sys.suspend & SUSPEND_ENERGIZE) { // De-energize system if safety door has been opened.
          spindle_stop();
          coolant_stop();
          // TODO: Install parking motion here.
        }
        bit_true(sys.suspend,SUSPEND_ENABLE_READY);
      } else { // Motion is complete. Includes CYCLE, HOMING, and MOTION_CANCEL states.
        sys.suspend = SUSPEND_DISABLE;
        sys.state = STATE_IDLE;
      }
      bit_false_atomic(sys_rt_exec_state,EXEC_CYCLE_STOP);
    }
    
  }

  // Overrides flag byte (sys.override) and execution should be installed here, since they 
  // are realtime and require a direct and controlled interface to the main stepper program.

  // Reload step segment buffer
  if (sys.state & (STATE_CYCLE | STATE_HOLD | STATE_MOTION_CANCEL | STATE_SAFETY_DOOR | STATE_HOMING)) { st_prep_buffer(); }  
  
  // If safety door was opened, actively check when safety door is closed and ready to resume.
  // NOTE: This unlocks the SAFETY_DOOR state to a HOLD state, such that CYCLE_START can activate a resume.
  if (sys.state == STATE_SAFETY_DOOR) { 
    if (bit_istrue(sys.suspend,SUSPEND_ENABLE_READY)) { 
      #ifndef DEFAULTS_TRINAMIC
      if (!(system_check_safety_door_ajar())) {
        sys.state = STATE_HOLD; // Update to HOLD state to indicate door is closed and ready to resume.
      }
      #endif
    }
  }

  } while(sys.suspend); // Check for system suspend state before exiting.
  
}