#define X_STEP_BIT      2  // Uno Digital Pin 2
  #define Y_STEP_BIT      3  // Uno Digital Pin 3
  #define Z_STEP_BIT      4  // Uno Digital Pin 4
  #define X_DIRECTION_BIT   5  // Uno Digital Pin 5
  #define Y_DIRECTION_BIT   6  // Uno Digital Pin 6
  #define Z_DIRECTION_BIT   7  // Uno Digital Pin 7
  #define STEPPERS_DISABLE_BIT    0  // Uno Digital Pin 8
  #define X_LIMIT_BIT      1  // Uno Digital Pin 9
  #define Y_LIMIT_BIT      2  // Uno Digital Pin 10
    #define Z_LIMIT_BIT	   4 // Uno Digital Pin 12
    #define Z_LIMIT_BIT    3  // Uno Digital Pin 11
        #define SPINDLE_ENABLE_BIT    5  // Uno Digital Pin 13 (NOTE: D13 can't be pulled-high input due to LED.)
        #define SPINDLE_ENABLE_BIT    3  // Uno Digital Pin 11
      #define SPINDLE_ENABLE_BIT    4  // Uno Digital Pin 12
      #define SPINDLE_DIRECTION_BIT   5  // Uno Digital Pin 13 (NOTE: D13 can't be pulled-high input due to LED.)
    #define SPINDLE_PWM_BIT   3    // Uno Digital Pin 11
      #define COOLANT_FLOOD_BIT   5  // Uno Digital Pin 13
        #define SPINDLE_ENABLE_BIT    3  // Uno Digital Pin 11
        #define SPINDLE_ENABLE_BIT    4  // Uno Digital Pin 12
      #define SPINDLE_PWM_BIT   3    // Uno Digital Pin 11
      #define DUAL_STEP_BIT       4  // Uno Digital Pin 12
      #define DUAL_DIRECTION_BIT  5  // Uno Digital Pin 13


/* from 
  cpu_map.h - CPU and pin mapping configuration file
  Part of Grbl
*/

  #define X_STEP_BIT      2  // Uno Digital Pin 2
  #define Y_STEP_BIT      3  // Uno Digital Pin 3
  #define Z_STEP_BIT      4  // Uno Digital Pin 4
  #define X_DIRECTION_BIT   5  // Uno Digital Pin 5
  #define Y_DIRECTION_BIT   6  // Uno Digital Pin 6
  #define Z_DIRECTION_BIT   7  // Uno Digital Pin 7
  #define X_LIMIT_BIT      1  // Uno Digital Pin 9
  #define Y_LIMIT_BIT      2  // Uno Digital Pin 10
  #ifdef VARIABLE_SPINDLE // Z Limit pin and spindle enabled swapped to access hardware PWM on Pin 11.
    #define Z_LIMIT_BIT	   4 // Uno Digital Pin 12
  #else
    #define Z_LIMIT_BIT    3  // Uno Digital Pin 11 (langmuir plasma is this case, NOT VARIABLE_SPINDLE (ab)
  #endif

  #define CONTROL_RESET_BIT         0  // Uno Analog Pin 0
  #define CONTROL_FEED_HOLD_BIT     1  // Uno Analog Pin 1
  #define CONTROL_CYCLE_START_BIT   2  // Uno Analog Pin 2
  #define CONTROL_SAFETY_DOOR_BIT   1  // Uno Analog Pin 1 NOTE: Safety door is shared with feed hold. Enabled by config define.
  #define PROBE_BIT       5  // Uno Analog Pin 5

  #if !defined(ENABLE_DUAL_AXIS)
// this might NOT be the lamgmuir case... at quelab (ab)
    #define COOLANT_FLOOD_BIT   3  // Uno Analog Pin 3
    #define COOLANT_MIST_BIT   4  // Uno Analog Pin 4
    #ifdef VARIABLE_SPINDLE
      #ifdef USE_SPINDLE_DIR_AS_ENABLE_PIN
        // If enabled, spindle direction pin now used as spindle enable, while PWM remains on D11.
        #define SPINDLE_ENABLE_BIT    5  // Uno Digital Pin 13 (NOTE: D13 can't be pulled-high input due to LED.)
      #else
        #define SPINDLE_ENABLE_BIT    3  // Uno Digital Pin 11
      #endif
    #else
      #define SPINDLE_ENABLE_BIT    4  // Uno Digital Pin 12 (i think this is langmuir case, where VARIABLE_SPINDLE is disabled)
    #endif
    #ifndef USE_SPINDLE_DIR_AS_ENABLE_PIN
      #define SPINDLE_DIRECTION_BIT   5  // Uno Digital Pin 13 (NOTE: D13 can't be pulled-high input due to LED.)
    #endif

    #define SPINDLE_PWM_BIT   3    // Uno Digital Pin 11
  
  #else

    // Dual axis feature requires an independent step pulse pin to operate. The independent direction pin is not 
    // absolutely necessary but facilitates easy direction inverting with a Grbl $$ setting. These pins replace 
    // the spindle direction and optional coolant mist pins.

    #ifdef DUAL_AXIS_CONFIG_PROTONEER_V3_51
      // NOTE: Step pulse and direction pins may be on any port and output pin.
      #define DUAL_STEP_BIT       4  // Uno Analog Pin 4
      #define DUAL_DIRECTION_BIT  3  // Uno Analog Pin 3
      #define COOLANT_FLOOD_BIT   5  // Uno Digital Pin 13

      #ifdef VARIABLE_SPINDLE
        // NOTE: USE_SPINDLE_DIR_AS_ENABLE_PIN not supported with dual axis feature.
        #define SPINDLE_ENABLE_BIT    3  // Uno Digital Pin 11
      #else
        #define SPINDLE_ENABLE_BIT    4  // Uno Digital Pin 12 (likely langmuir pin at quelab (ab))
      #endif

      #define SPINDLE_PWM_BIT   3    // Uno Digital Pin 11
    #endif

    // NOTE: Variable spindle not supported with this shield.
    #ifdef DUAL_AXIS_CONFIG_CNC_SHIELD_CLONE
      // NOTE: Step pulse and direction pins may be on any port and output pin.
      #define DUAL_STEP_BIT       4  // Uno Digital Pin 12
      #define DUAL_DIRECTION_BIT  5  // Uno Digital Pin 13
      #define COOLANT_FLOOD_BIT   4  // Uno Analog Pin 4
      #define SPINDLE_ENABLE_BIT    3  // Uno Analog Pin 3
    #endif

  #endif

#endif