diff --git a/config.h b/config.h
index db42f7e43..419a03e72 100644
--- a/config.h
+++ b/config.h
@@ -1,23 +1,20 @@
 /*
   config.h - compile time configuration
-  Part of Grbl
+  Part of LasaurGrbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
   Copyright (c) 2011 Sungeun K. Jeon
   Copyright (c) 2011 Stefan Hechenberger
 
-  Grbl is free software: you can redistribute it and/or modify
+  LasaurGrbl 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,
+  LasaurGrbl 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/>.
 */
 
 #ifndef config_h
@@ -31,9 +28,9 @@
 #define BAUD_RATE 9600
 
 
-#define LIMIT_OVERWRITE_DDR     DDRD
-#define LIMIT_OVERWRITE_PORT    PORTD
-#define LIMIT_OVERWRITE_BIT     7
+#define LIMITS_OVERWRITE_DDR     DDRD
+#define LIMITS_OVERWRITE_PORT    PORTD
+#define LIMITS_OVERWRITE_BIT     7
 
 #define SENSE_DDR               DDRD
 #define SENSE_PORT              PORTD
@@ -64,11 +61,13 @@
 #define Z_DIRECTION_BIT         5
 
 
+#define SENSE_MASK ((1<<POWER_BIT)|(1<<CHILLER_BIT)|(1<<DOOR_BIT))
 #define LIMIT_MASK ((1<<X1_LIMIT_BIT)|(1<<X2_LIMIT_BIT)|(1<<Y1_LIMIT_BIT)|(1<<Y2_LIMIT_BIT))
 #define STEPPING_MASK ((1<<X_STEP_BIT)|(1<<Y_STEP_BIT)|(1<<Z_STEP_BIT))
 #define DIRECTION_MASK ((1<<X_DIRECTION_BIT)|(1<<Y_DIRECTION_BIT)|(1<<Z_DIRECTION_BIT))
 #define INVERT_MASK 24U  // 0x00011000 invert direction pin 3 and 4, (1<<X_DIRECTION_BIT) | (1<<Y_DIRECTION_BIT)
-
+// #define INVERT_MASK 24U  // typical forLin Engineering Steppers
+// #define INVERT_MASK 0U   // typical for Nanotec Steppers
 
 #define CONFIG_X_STEPS_PER_MM 32.80839895 //microsteps/mm
 #define CONFIG_Y_STEPS_PER_MM 32.80839895 //microsteps/mm
diff --git a/flash.py b/flash.py
index fa4881a0f..5e90e00dc 100644
--- a/flash.py
+++ b/flash.py
@@ -70,7 +70,7 @@ def build():
     BITRATE = "115200"
 
     BUILDNAME = "LasaurGrbl"
-    OBJECTS  = ["main", "serial", "gcode", "planner", "output_control", "input_control", "stepper"]
+    OBJECTS  = ["main", "serial", "gcode", "planner", "io_control", "stepper"]
              
     COMPILE = AVRGCCAPP + " -Wall -Os -DF_CPU=" + CLOCK + " -mmcu=" + DEVICE + " -I. -ffunction-sections"
 
diff --git a/gcode.c b/gcode.c
index de26461f2..b10f0b0b5 100644
--- a/gcode.c
+++ b/gcode.c
@@ -1,21 +1,23 @@
 /*
-gcode.c - rs274/ngc parser.
-Part of LasaurGrbl
+  gcode.c - rs274/ngc parser.
+  Part of LasaurGrbl
 
-Copyright (c) 2009-2011 Simen Svale Skogsrud
-Copyright (c) 2011 Stefan Hechenberger
-Copyright (c) 2011 Sungeun K. Jeon
-Inspired by the Arduino GCode Interpreter by Mike Ellery and the
-NIST RS274/NGC Interpreter by Kramer, Proctor and Messina.
-LasaurGrbl 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.
+  Copyright (c) 2009-2011 Simen Svale Skogsrud
+  Copyright (c) 2011 Stefan Hechenberger
+  Copyright (c) 2011 Sungeun K. Jeon
+  
+  Inspired by the Arduino GCode Interpreter by Mike Ellery and the
+  NIST RS274/NGC Interpreter by Kramer, Proctor and Messina.  
+
+  LasaurGrbl 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.
 
-LasaurGrbl 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.
+  LasaurGrbl 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.
 */
 
 #include <string.h>
@@ -26,11 +28,10 @@ GNU General Public License for more details.
 #include "gcode.h"
 #include "config.h"
 #include "serial.h"
-#include "input_control.h"
-#include "output_control.h"
+#include "io_control.h"
+#include "planner.h"
 #include "stepper.h"
 
-
 #define MM_PER_INCH (25.4)
 
 #define NEXT_ACTION_NONE 0
@@ -303,7 +304,7 @@ uint8_t gcode_execute_line(char *line) {
                     gc.seek_rate, 0 );
       break;
     case NEXT_ACTION_HOMING_CYCLE:
-      limits_homing_cycle();
+      stepper_homing_cycle();
       // now that we are at the physical home
       // zero all the position vectors
       clear_vector(gc.position);
@@ -327,13 +328,13 @@ uint8_t gcode_execute_line(char *line) {
       }
       break;
     case NEXT_ACTION_AIRGAS_DISABLE:
-      planner_airgas_disable();
+      planner_control_airgas_disable();
       break;
     case NEXT_ACTION_AIR_ENABLE:
-      planner_air_enable();
+      planner_control_air_enable();
       break;
     case NEXT_ACTION_GAS_ENABLE:
-      planner_gas_enable();
+      planner_control_gas_enable();
       break;
   }
   
diff --git a/input_control.c b/input_control.c
deleted file mode 100644
index 58578fc83..000000000
--- a/input_control.c
+++ /dev/null
@@ -1,116 +0,0 @@
-/*
-  limits.h - code pertaining to limit-switches and performing the homing cycle
-  Part of Grbl
-
-  Copyright (c) 2009-2011 Simen Svale Skogsrud
-
-  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/>.
-*/
-  
-#include <util/delay.h>
-#include <avr/io.h>
-#include "config.h"
-#include "stepper.h"
-#include "planner.h"
-#include "input_control.h"
-
-
-void limits_overwrite_disable();
-
-
-void limits_init() {
-  LIMIT_DDR &= ~(LIMIT_MASK);
-  LIMIT_PORT |= LIMIT_MASK;     //activate pull-up resistors  
-
-  // define as output pin
-  LIMIT_OVERWRITE_DDR |= 1<<LIMIT_OVERWRITE_BIT;
-  limits_overwrite_disable();
-}
-
-
-void limits_overwrite_enable() {
-  // sinking the pin overwrites the limit stop hard logic
-  LIMIT_OVERWRITE_PORT &= ~(1<<LIMIT_OVERWRITE_BIT);  
-}
-
-void limits_overwrite_disable() {
-  LIMIT_OVERWRITE_PORT |= (1<<LIMIT_OVERWRITE_BIT);  
-}
-
-static void homing_cycle(bool x_axis, bool y_axis, bool z_axis, bool reverse_direction, uint32_t microseconds_per_pulse) {
-  
-  uint32_t step_delay = microseconds_per_pulse - CONFIG_PULSE_MICROSECONDS;
-  uint8_t out_bits = DIRECTION_MASK;
-  uint8_t limit_bits;
-  
-  if (x_axis) { out_bits |= (1<<X_STEP_BIT); }
-  if (y_axis) { out_bits |= (1<<Y_STEP_BIT); }
-  if (z_axis) { out_bits |= (1<<Z_STEP_BIT); }
-  
-  // Invert direction bits if this is a reverse homing_cycle
-  if (reverse_direction) {
-    out_bits ^= DIRECTION_MASK;
-  }
-  
-  // Apply the global invert mask
-  out_bits ^= INVERT_MASK;
-  
-  // Set direction pins
-  STEPPING_PORT = (STEPPING_PORT & ~DIRECTION_MASK) | (out_bits & DIRECTION_MASK);
-  
-  for(;;) {
-    limit_bits = LIMIT_PIN;
-    if (reverse_direction) {         
-      // Invert limit_bits if this is a reverse homing_cycle
-      limit_bits ^= LIMIT_MASK;
-    }
-    if (x_axis && !(limit_bits & (1<<X1_LIMIT_BIT))) {
-      x_axis = false;
-      out_bits ^= (1<<X_STEP_BIT);      
-    }    
-    if (y_axis && !(limit_bits & (1<<Y1_LIMIT_BIT))) {
-      y_axis = false;
-      out_bits ^= (1<<Y_STEP_BIT);
-    }    
- //   if (z_axis && !(limit_bits & (1<<Z1_LIMIT_BIT))) {
- //     z_axis = false;
- //     out_bits ^= (1<<Z_STEP_BIT);
- //   }
-    if(x_axis || y_axis || z_axis) {
-        // step all axes still in out_bits
-        STEPPING_PORT |= out_bits & STEPPING_MASK;
-        _delay_us(CONFIG_PULSE_MICROSECONDS);
-        STEPPING_PORT ^= out_bits & STEPPING_MASK;
-        _delay_us(step_delay);
-    } else { 
-        return;
-    }
-  }
-  return;
-}
-
-static void approach_limit_switch(bool x, bool y, bool z) {
-  homing_cycle(x, y, z,false, 1000);
-}
-
-static void leave_limit_switch(bool x, bool y, bool z) {
-  homing_cycle(x, y, z, true, 100000);
-}
-
-void limits_homing_cycle() {
-  stepper_synchronize();
-  // home the x and y axis
-  approach_limit_switch(true, true, false);
-  leave_limit_switch(true, true, false);
-}
diff --git a/input_control.h b/input_control.h
deleted file mode 100644
index dcf82d4ce..000000000
--- a/input_control.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/*
-limits.h - code pertaining to limit-switches and performing the homing cycle
-Part of Grbl
-
-Copyright (c) 2009-2011 Simen Svale Skogsrud
-
-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/>.
-*/
-
-#ifndef input_control_h
-#define input_control_h
-
-// initialize the limits module
-void limits_init();
-
-// perform the homing cycle
-void limits_homing_cycle();
-
-// dis/enable if controller can still 
-// move while a limit switch is triggering
-void limits_overwrite_enable();
-void limits_overwrite_disable();
-
-#endif
\ No newline at end of file
diff --git a/main.c b/main.c
index 56348191c..3ed768bb8 100644
--- a/main.c
+++ b/main.c
@@ -1,21 +1,18 @@
 /*
   main.c - An embedded CNC Controller with rs274/ngc (g-code) support
-  Part of Grbl
+  Part of LasaurGrbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
 
-  Grbl is free software: you can redistribute it and/or modify
+  LasaurGrbl 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,
+  LasaurGrbl 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/>.
 */
 
 #include <avr/io.h>
@@ -25,8 +22,7 @@
 #include "config.h"
 #include "planner.h"
 #include "stepper.h"
-#include "input_control.h"
-#include "output_control.h"
+#include "io_control.h"
 #include "gcode.h"
 #include "serial.h"
 
@@ -34,13 +30,12 @@
 int main() {
   sei();  //enable interrupts
   serial_init();
+  gcode_init();
   planner_init();      
   stepper_init();
-  laser_init();
-  airgas_init();
-  gcode_init();
-  limits_init();
-                    
+  sense_init();
+  control_init();
+  
   while(true) {
     gcode_process_line();
   }
diff --git a/output_control.c b/output_control.c
deleted file mode 100644
index e08bd1ca2..000000000
--- a/output_control.c
+++ /dev/null
@@ -1,87 +0,0 @@
-/*
-  output_control.c - high level interface for issuing motion commands
-  Part of Grbl
-
-  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011 Sungeun K. Jeon
-  Copyright (c) 2011 Stefan hechenberger  
-  
-  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/>.
-*/
-
-#include <avr/io.h>
-#include <util/delay.h>
-#include <math.h>
-#include <stdlib.h>
-#include "config.h"
-#include "input_control.h"
-#include "output_control.h"
-#include "stepper.h"
-#include "planner.h"
-
-
-
-void laser_init() {
-  // Setup Timer0 for a 31.25kH "phase correct PWM" wave (assuming a 16Mhz clock)
-  // Timer0 can pwm either PD5 (OC0B) or PD6 (OC0A), we use PD6
-  // TCCR0A and TCCR0B are the registers to setup Timer0
-  // see chapter "8-bit Timer/Counter0 with PWM" in Atmga328 specs
-  // OCR0A sets the duty cycle 0-255 corresponding to 0-100%
-  DDRD |= (1 << DDD6);      // set PD6 as an output
-  OCR0A = 0;              // set PWM to a 0% duty cycle
-  TCCR0A |= (1 << COM0A1);  // set non-inverting mode on OC0A, PD6, Arduino pin 6
-  TCCR0A |= (1 << WGM00);   // set phase correct PWM mode, has half the freq of fast PWM
-  TCCR0B |= (1 << CS00);    // prescaler to 1, PWMfreq = 16000/(2*256*1) = 31.25kH
-  
-  // Setup laser enable pin.
-  // LASER_ENABLE_DDR |= (1 << LASER_ENABLE_BIT);
-  // laser_enable();
-}
-
-void laser_enable() {
-  // sinking the pin enables the laser
-  // LASER_ENABLE_PORT &= ~(1<<LASER_ENABLE_BIT);
-}
-
-void laser_disable() {
-  // LASER_ENABLE_PORT |= 1<<LASER_ENABLE_BIT;
-}
-
-void set_laser_intensity(uint8_t intensity) {
-  OCR0A = intensity;
-}
-
-
-
-void airgas_init() {
-  AIRGAS_DDR |= (1 << AIR_BIT);  // set as output pin
-  AIRGAS_DDR |= (1 << GAS_BIT);  // set as output pin
-  airgas_disable();    
-}
-
-
-void airgas_disable() {
-  AIRGAS_PORT |= (1 << AIR_BIT);
-  AIRGAS_PORT |= (1 << GAS_BIT);
-}
-
-void air_enable() {
-  AIRGAS_PORT &= ~(1 << AIR_BIT);
-}
-
-void gas_enable() {
-  AIRGAS_PORT &= ~(1 << GAS_BIT);
-}
-
-
diff --git a/output_control.h b/output_control.h
deleted file mode 100644
index 307ce490b..000000000
--- a/output_control.h
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
-  output_control.h - high level interface for issuing motion commands
-  Part of Grbl
-
-  Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011 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/>.
-*/
-
-#ifndef output_control_h
-#define output_control_h
-
-#include <avr/io.h>
-#include "config.h"
-#include "planner.h"
-#include "stepper.h"
-
-
-void laser_init();
-void set_laser_intensity(uint8_t intensity);  //0-255 is 0-100%
-
-void airgas_init();
-void airgas_disable();
-void air_enable();
-void gas_enable();
-
-
-#endif
diff --git a/planner.c b/planner.c
index 5bec02462..640be67f7 100644
--- a/planner.c
+++ b/planner.c
@@ -1,26 +1,22 @@
 /*
   planner.c - buffers movement commands and manages the acceleration profile plan
-  Part of Grbl
+  Part of LasaurGrbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
   Copyright (c) 2011 Sungeun K. Jeon
-  
-  Grbl is free software: you can redistribute it and/or modify
+  Copyright (c) 2011 Stefan Hechenberger
+
+  LasaurGrbl 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,
+  LasaurGrbl 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/>.
 */
 
-/* The ring buffer implementation gleaned from the wiring_serial library by David A. Mellis. */
-
 #include <inttypes.h>
 #include <math.h>
 #include <stdlib.h>
diff --git a/planner.h b/planner.h
index 4078dab50..d97d0d2aa 100644
--- a/planner.h
+++ b/planner.h
@@ -1,24 +1,23 @@
 /*
-  planner.h - buffers movement commands and manages the acceleration profile plan
-  Part of Grbl
+  planner.c - buffers movement commands and manages the acceleration profile plan
+  Part of LasaurGrbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
-  Copyright (c) 2011 Sungeun K. Jeon  
+  Copyright (c) 2011 Sungeun K. Jeon
+  Copyright (c) 2011 Stefan Hechenberger
 
-  Grbl is free software: you can redistribute it and/or modify
+  LasaurGrbl 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,
+  LasaurGrbl 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/>.
 */
 
+
 #ifndef planner_h
 #define planner_h
                  
@@ -33,9 +32,9 @@
 #define TYPE_GAS_ENABLE 4
 
 #define planner_stop() planner_command(TYPE_STOP)
-#define planner_airgas_disable() planner_command(TYPE_AIRGAS_DISABLE)
-#define planner_air_enable() planner_command(TYPE_AIR_ENABLE)
-#define planner_gas_enable() planner_command(TYPE_GAS_ENABLE)
+#define planner_control_airgas_disable() planner_command(TYPE_AIRGAS_DISABLE)
+#define planner_control_air_enable() planner_command(TYPE_AIR_ENABLE)
+#define planner_control_gas_enable() planner_command(TYPE_GAS_ENABLE)
 
 
 // This struct is used when buffering the setup for each linear movement "nominal" values are as specified in 
diff --git a/serial.c b/serial.c
index 69fb803d5..d87e25015 100644
--- a/serial.c
+++ b/serial.c
@@ -1,26 +1,25 @@
 /*
-  serial.c - Low level functions for sending and recieving bytes via the serial port
-  Part of Grbl
+  serial.c - Low level functions for sending and recieving bytes via the serial port.
+  Part of LasaurGrbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
+  Copyright (c) 2011 Sungeun K. Jeon
+  Copyright (c) 2011 Stefan Hechenberger
 
-  Grbl is free software: you can redistribute it and/or modify
+  Inspired by the wiring_serial module by David A. Mellis which
+  used to be a part of the Arduino project.
+   
+  LasaurGrbl 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,
+  LasaurGrbl 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/>.
 */
 
-/* This code was initially inspired by the wiring_serial module by David A. Mellis which
-   used to be a part of the Arduino project. */ 
-
 #include <avr/interrupt.h>
 #include <avr/sleep.h>
 #include <math.h>
diff --git a/serial.h b/serial.h
index 7a056cdb6..be6caa95c 100644
--- a/serial.h
+++ b/serial.h
@@ -1,26 +1,25 @@
 /*
-  serial.c - Low level functions for sending and recieving bytes via the serial port
-  Part of Grbl
+  serial.c - Low level functions for sending and recieving bytes via the serial port.
+  Part of LasaurGrbl
 
   Copyright (c) 2009-2011 Simen Svale Skogsrud
+  Copyright (c) 2011 Sungeun K. Jeon
+  Copyright (c) 2011 Stefan Hechenberger
 
-  Grbl is free software: you can redistribute it and/or modify
+  Inspired by the wiring_serial module by David A. Mellis which
+  used to be a part of the Arduino project.
+   
+  LasaurGrbl 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,
+  LasaurGrbl 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/>.
 */
 
-/* This code was initially inspired by the wiring_serial module by David A. Mellis which
-   used to be a part of the Arduino project. */ 
-
 #ifndef serial_h
 #define serial_h
 
diff --git a/stepper.c b/stepper.c
index b07bcd347..681c194bc 100644
--- a/stepper.c
+++ b/stepper.c
@@ -7,7 +7,6 @@
   Copyright (c) 2011 Stefan Hechenberger
   Copyright (c) 2009-2011 Simen Svale Skogsrud
   Copyright (c) 2011 Sungeun K. Jeon
-  Copyright (c) 2011 Arthur Wolf
   
   Inspired by the 'RepRap cartesian firmware' by Zack Smith and 
   Philipp Tiefenbacher.
@@ -49,8 +48,7 @@
 #include "stepper.h"
 #include "config.h"
 #include "planner.h"
-#include "input_control.h"
-#include "output_control.h"
+#include "io_control.h"
 
 
 #define CYCLES_PER_MICROSECOND (F_CPU/1000000)  //16000000/1000000 = 16
@@ -144,7 +142,7 @@ void stepper_go_idle() {
   current_block = NULL;
   // Disable stepper driver interrupt
   TIMSK1 &= ~(1<<OCIE1A);
-  set_laser_intensity(0);
+  control_laser_intensity(0);
 }
 
 // stop processing command blocks on next ISR call
@@ -321,19 +319,20 @@ ISR(TIMER1_COMPA_vect) {
       break; 
 
     case TYPE_AIRGAS_DISABLE:
-      airgas_disable();
+      control_air(false);
+      control_gas(false);
       current_block = NULL;
       planner_discard_current_block();  
       break;
 
     case TYPE_AIR_ENABLE:
-      air_enable();
+      control_air(true);
       current_block = NULL;
       planner_discard_current_block();  
       break;
 
     case TYPE_GAS_ENABLE:
-      gas_enable();
+      control_gas(true);
       current_block = NULL;
       planner_discard_current_block();  
       break;      
@@ -404,9 +403,78 @@ static void adjust_speed( uint32_t steps_per_minute ) {
   cycles_per_step_event = config_step_timer((CYCLES_PER_MICROSECOND*1000000*60)/steps_per_minute);
 
   // run at constant intensity for now
-  set_laser_intensity(current_block->nominal_laser_intensity);
+  control_laser_intensity(current_block->nominal_laser_intensity);
 }
 
 
 
 
+
+static void homing_cycle(bool x_axis, bool y_axis, bool z_axis, bool reverse_direction, uint32_t microseconds_per_pulse) {
+  
+  uint32_t step_delay = microseconds_per_pulse - CONFIG_PULSE_MICROSECONDS;
+  uint8_t out_bits = DIRECTION_MASK;
+  uint8_t limit_bits;
+  
+  if (x_axis) { out_bits |= (1<<X_STEP_BIT); }
+  if (y_axis) { out_bits |= (1<<Y_STEP_BIT); }
+  if (z_axis) { out_bits |= (1<<Z_STEP_BIT); }
+  
+  // Invert direction bits if this is a reverse homing_cycle
+  if (reverse_direction) {
+    out_bits ^= DIRECTION_MASK;
+  }
+  
+  // Apply the global invert mask
+  out_bits ^= INVERT_MASK;
+  
+  // Set direction pins
+  STEPPING_PORT = (STEPPING_PORT & ~DIRECTION_MASK) | (out_bits & DIRECTION_MASK);
+  
+  for(;;) {
+    limit_bits = LIMIT_PIN;
+    if (reverse_direction) {         
+      // Invert limit_bits if this is a reverse homing_cycle
+      limit_bits ^= LIMIT_MASK;
+    }
+    if (x_axis && !(limit_bits & (1<<X1_LIMIT_BIT))) {
+      x_axis = false;
+      out_bits ^= (1<<X_STEP_BIT);      
+    }    
+    if (y_axis && !(limit_bits & (1<<Y1_LIMIT_BIT))) {
+      y_axis = false;
+      out_bits ^= (1<<Y_STEP_BIT);
+    }    
+ //   if (z_axis && !(limit_bits & (1<<Z1_LIMIT_BIT))) {
+ //     z_axis = false;
+ //     out_bits ^= (1<<Z_STEP_BIT);
+ //   }
+    if(x_axis || y_axis || z_axis) {
+        // step all axes still in out_bits
+        STEPPING_PORT |= out_bits & STEPPING_MASK;
+        _delay_us(CONFIG_PULSE_MICROSECONDS);
+        STEPPING_PORT ^= out_bits & STEPPING_MASK;
+        _delay_us(step_delay);
+    } else { 
+        return;
+    }
+  }
+  return;
+}
+
+static void approach_limit_switch(bool x, bool y, bool z) {
+  homing_cycle(x, y, z,false, 1000);
+}
+
+static void leave_limit_switch(bool x, bool y, bool z) {
+  homing_cycle(x, y, z, true, 100000);
+}
+
+void stepper_homing_cycle() {
+  stepper_synchronize();
+  // home the x and y axis
+  approach_limit_switch(true, true, false);
+  leave_limit_switch(true, true, false);
+}
+
+
diff --git a/stepper.h b/stepper.h
index fbf074187..07b3cdd9c 100644
--- a/stepper.h
+++ b/stepper.h
@@ -7,7 +7,6 @@
   Copyright (c) 2011 Stefan Hechenberger
   Copyright (c) 2009-2011 Simen Svale Skogsrud
   Copyright (c) 2011 Sungeun K. Jeon
-  Copyright (c) 2011 Arthur Wolf
   
   Inspired by the 'RepRap cartesian firmware' by Zack Smith and 
   Philipp Tiefenbacher.
@@ -53,4 +52,7 @@ double stepper_get_position_y();
 double stepper_get_position_z();
 void stepper_set_position(double x, double y, double z);
 
+// perform the homing cycle
+void stepper_homing_cycle();
+
 #endif