main.c

/*
  main.c - An embedded CNC Controller with rs274/ngc (g-code) support
  Part of Grbl

  Copyright (c) 2009-2011 Simen Svale Skogsrud
  Copyright (c) 2011-2012 Sungeun K. Jeon

  Grbl is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Grbl is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
*/

/* A big thanks to Alden Hart of Synthetos, supplier of grblshield and TinyG, who has
   been integral throughout the development of the higher level details of Grbl, as well
   as being a consistent sounding board for the future of accessible and free CNC. */

#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include "config.h"
#include "planner.h"
#include "nuts_bolts.h"
#include "stepper.h"
#include "spindle_control.h"
#include "coolant_control.h"
#include "motion_control.h"
#include "gcode.h"
#include "protocol.h"
#include "limits.h"
#include "report.h"
#include "settings.h"
#include "serial.h"
#ifdef MCP23017_PRESENT
#include "MCP23017.h"
#endif
// Declare system global variable structure
system_t sys; 

int main(void)
{
  // Initialize system
  serial_init(); // Setup serial baud rate and interrupts
  settings_init(); // Load grbl settings from EEPROM
  st_init(); // Setup stepper pins and interrupt timers
  sei(); // Enable interrupts
  
  memset(&sys, 0, sizeof(sys));  // Clear all system variables
  sys.abort = true;   // Set abort to complete initialization
  sys.state = STATE_INIT;  // Set alarm state to indicate unknown initial position
  
  for(;;) {
  
    // Execute system reset upon a system abort, where the main program will return to this loop.
    // Once here, it is safe to re-initialize the system. At startup, the system will automatically
    // reset to finish the initialization process.
    if (sys.abort) {
      // Reset system.
      #ifdef MCP23017_PRESENT
      MCP23017_begin(MCP23017_UNIT0);
      #endif
      serial_reset_read_buffer(); // Clear serial read buffer
      plan_init(); // Clear block buffer and planner variables
      gc_init(); // Set g-code parser to default state
      protocol_init(); // Clear incoming line data and execute startup lines
      spindle_init();
      #ifdef COOLANT_PRESENT
      coolant_init();
      #endif
      limits_init();
      home_init();
      st_reset(); // Clear stepper subsystem variables.

      // Sync cleared gcode and planner positions to current system position, which is only
      // cleared upon startup, not a reset/abort. 
      sys_sync_current_position();

      // Reset system variables.
      sys.abort = false;
      sys.execute = 0;
      if (bit_istrue(settings.flags,BITFLAG_AUTO_START)) { sys.auto_start = true; }
      
      // Check for power-up and set system alarm if homing is enabled to force homing cycle
      // by setting Grbl's alarm state. Alarm locks out all g-code commands, including the
      // startup scripts, but allows access to settings and internal commands. Only a homing
      // cycle '$H' or kill alarm locks '$X' will disable the alarm.
      // NOTE: The startup script will run after successful completion of the homing cycle, but
      // not after disabling the alarm locks. Prevents motion startup blocks from crashing into
      // things uncontrollably. Very bad.
      #ifdef HOMING_INIT_LOCK
        if (sys.state == STATE_INIT && bit_istrue(settings.flags,BITFLAG_HOMING_ENABLE)) { sys.state = STATE_ALARM; }
      #endif
      
      // Check for and report alarm state after a reset, error, or an initial power up.
      if (sys.state == STATE_ALARM) {
        report_feedback_message(MESSAGE_ALARM_LOCK); 
      } else {
        // All systems go. Set system to ready and execute startup script.
        sys.state = STATE_IDLE;
        protocol_execute_startup(); 
      }
    }
    
    protocol_execute_runtime();
    protocol_process(); // ... process the serial protocol
    
  }
  return 0;   /* never reached */
}