From 5e4e535ce8d0bc1f37464a20d0b29dc8678f032f Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Wed, 27 Apr 2016 07:15:20 -0700
Subject: [PATCH] Stepper and Endstops as singleton objects

---
 Marlin/Marlin.h        |   2 +-
 Marlin/Marlin_main.cpp | 223 ++++++-------
 Marlin/cardreader.cpp  |   2 +-
 Marlin/endstops.cpp    | 317 ++++++++++++++++++
 Marlin/endstops.h      |  94 ++++++
 Marlin/planner.cpp     |   8 +-
 Marlin/stepper.cpp     | 707 +++++++++--------------------------------
 Marlin/stepper.h       | 347 ++++++++++++++++----
 Marlin/temperature.cpp |   2 +-
 Marlin/ultralcd.cpp    |   6 +-
 10 files changed, 948 insertions(+), 760 deletions(-)
 create mode 100644 Marlin/endstops.cpp
 create mode 100644 Marlin/endstops.h

diff --git a/Marlin/Marlin.h b/Marlin/Marlin.h
index 9cd13c90ee..1db06e9bc2 100644
--- a/Marlin/Marlin.h
+++ b/Marlin/Marlin.h
@@ -216,7 +216,7 @@ void manage_inactivity(bool ignore_stepper_queue = false);
  */
 enum AxisEnum {X_AXIS = 0, A_AXIS = 0, Y_AXIS = 1, B_AXIS = 1, Z_AXIS = 2, C_AXIS = 2, E_AXIS = 3, X_HEAD = 4, Y_HEAD = 5, Z_HEAD = 5};
 
-enum EndstopEnum {X_MIN = 0, Y_MIN = 1, Z_MIN = 2, Z_MIN_PROBE = 3, X_MAX = 4, Y_MAX = 5, Z_MAX = 6, Z2_MIN = 7, Z2_MAX = 8};
+#define _AXIS(AXIS) AXIS ##_AXIS
 
 void enable_all_steppers();
 void disable_all_steppers();
diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 37c472f3ca..7cc7c028c8 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -48,6 +48,7 @@
 #include "ultralcd.h"
 #include "planner.h"
 #include "stepper.h"
+#include "endstops.h"
 #include "temperature.h"
 #include "cardreader.h"
 #include "configuration_store.h"
@@ -547,10 +548,6 @@ static void report_current_position();
   float extrude_min_temp = EXTRUDE_MINTEMP;
 #endif
 
-#if ENABLED(HAS_Z_MIN_PROBE)
-  extern volatile bool z_probe_is_active;
-#endif
-
 #if ENABLED(SDSUPPORT)
   #include "SdFatUtil.h"
   int freeMemory() { return SdFatUtil::FreeRam(); }
@@ -711,7 +708,7 @@ void servo_init() {
 
    #if HAS_SERVO_ENDSTOPS
 
-    z_probe_is_active = false;
+    endstops.enable_z_probe(false);
 
     /**
      * Set position of all defined Servo Endstops
@@ -831,7 +828,7 @@ void setup() {
     watchdog_init();
   #endif
 
-  st_init();    // Initialize stepper, this enables interrupts!
+  stepper.init();    // Initialize stepper, this enables interrupts!
   setup_photpin();
   servo_init();
 
@@ -915,7 +912,7 @@ void loop() {
     commands_in_queue--;
     cmd_queue_index_r = (cmd_queue_index_r + 1) % BUFSIZE;
   }
-  checkHitEndstops();
+  endstops.report_state();
   idle();
 }
 
@@ -1445,9 +1442,9 @@ static void setup_for_endstop_move() {
   feedrate_multiplier = 100;
   refresh_cmd_timeout();
   #if ENABLED(DEBUG_LEVELING_FEATURE)
-    if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("setup_for_endstop_move > enable_endstops(true)");
+    if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("setup_for_endstop_move > endstops.enable()");
   #endif
-  enable_endstops(true);
+  endstops.enable();
 }
 
 #if ENABLED(AUTO_BED_LEVELING_FEATURE)
@@ -1553,7 +1550,7 @@ static void setup_for_endstop_move() {
     #if ENABLED(DELTA)
 
       float start_z = current_position[Z_AXIS];
-      long start_steps = st_get_position(Z_AXIS);
+      long start_steps = stepper.position(Z_AXIS);
 
       #if ENABLED(DEBUG_LEVELING_FEATURE)
         if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("run_z_probe (DELTA) 1");
@@ -1563,14 +1560,14 @@ static void setup_for_endstop_move() {
       feedrate = homing_feedrate[Z_AXIS] / 4;
       destination[Z_AXIS] = -10;
       prepare_move_raw(); // this will also set_current_to_destination
-      st_synchronize();
-      endstops_hit_on_purpose(); // clear endstop hit flags
+      stepper.synchronize();
+      endstops.hit_on_purpose(); // clear endstop hit flags
 
       /**
        * We have to let the planner know where we are right now as it
        * is not where we said to go.
        */
-      long stop_steps = st_get_position(Z_AXIS);
+      long stop_steps = stepper.position(Z_AXIS);
       float mm = start_z - float(start_steps - stop_steps) / axis_steps_per_unit[Z_AXIS];
       current_position[Z_AXIS] = mm;
 
@@ -1588,10 +1585,10 @@ static void setup_for_endstop_move() {
       // Move down until the Z probe (or endstop?) is triggered
       float zPosition = -(Z_MAX_LENGTH + 10);
       line_to_z(zPosition);
-      st_synchronize();
+      stepper.synchronize();
 
       // Tell the planner where we ended up - Get this from the stepper handler
-      zPosition = st_get_axis_position_mm(Z_AXIS);
+      zPosition = stepper.get_axis_position_mm(Z_AXIS);
       plan_set_position(
         current_position[X_AXIS], current_position[Y_AXIS], zPosition,
         current_position[E_AXIS]
@@ -1600,19 +1597,19 @@ static void setup_for_endstop_move() {
       // move up the retract distance
       zPosition += home_bump_mm(Z_AXIS);
       line_to_z(zPosition);
-      st_synchronize();
-      endstops_hit_on_purpose(); // clear endstop hit flags
+      stepper.synchronize();
+      endstops.hit_on_purpose(); // clear endstop hit flags
 
       // move back down slowly to find bed
       set_homing_bump_feedrate(Z_AXIS);
 
       zPosition -= home_bump_mm(Z_AXIS) * 2;
       line_to_z(zPosition);
-      st_synchronize();
-      endstops_hit_on_purpose(); // clear endstop hit flags
+      stepper.synchronize();
+      endstops.hit_on_purpose(); // clear endstop hit flags
 
       // Get the current stepper position after bumping an endstop
-      current_position[Z_AXIS] = st_get_axis_position_mm(Z_AXIS);
+      current_position[Z_AXIS] = stepper.get_axis_position_mm(Z_AXIS);
       sync_plan_position();
 
       #if ENABLED(DEBUG_LEVELING_FEATURE)
@@ -1641,7 +1638,7 @@ static void setup_for_endstop_move() {
       destination[Y_AXIS] = y;
       destination[Z_AXIS] = z;
       prepare_move_raw(); // this will also set_current_to_destination
-      st_synchronize();
+      stepper.synchronize();
 
     #else
 
@@ -1649,14 +1646,14 @@ static void setup_for_endstop_move() {
 
       current_position[Z_AXIS] = z;
       line_to_current_position();
-      st_synchronize();
+      stepper.synchronize();
 
       feedrate = xy_travel_speed;
 
       current_position[X_AXIS] = x;
       current_position[Y_AXIS] = y;
       line_to_current_position();
-      st_synchronize();
+      stepper.synchronize();
 
     #endif
 
@@ -1681,9 +1678,9 @@ static void setup_for_endstop_move() {
 
   static void clean_up_after_endstop_move() {
     #if ENABLED(DEBUG_LEVELING_FEATURE)
-      if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("clean_up_after_endstop_move > ENDSTOPS_ONLY_FOR_HOMING > endstops_not_homing()");
+      if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("clean_up_after_endstop_move > ENDSTOPS_ONLY_FOR_HOMING > endstops.not_homing()");
     #endif
-    endstops_not_homing();
+    endstops.not_homing();
     feedrate = saved_feedrate;
     feedrate_multiplier = saved_feedrate_multiplier;
     refresh_cmd_timeout();
@@ -1697,7 +1694,7 @@ static void setup_for_endstop_move() {
       if (DEBUGGING(LEVELING)) DEBUG_POS("deploy_z_probe", current_position);
     #endif
 
-    if (z_probe_is_active) return;
+    if (endstops.z_probe_enabled) return;
 
     #if HAS_SERVO_ENDSTOPS
 
@@ -1757,7 +1754,7 @@ static void setup_for_endstop_move() {
       destination[Y_AXIS] = destination[Y_AXIS] * 0.75;
       prepare_move_raw(); // this will also set_current_to_destination
 
-      st_synchronize();
+      stepper.synchronize();
 
       #if ENABLED(Z_MIN_PROBE_ENDSTOP)
         z_probe_endstop = (READ(Z_MIN_PROBE_PIN) != Z_MIN_PROBE_ENDSTOP_INVERTING);
@@ -1778,10 +1775,10 @@ static void setup_for_endstop_move() {
     #endif // Z_PROBE_ALLEN_KEY
 
     #if ENABLED(FIX_MOUNTED_PROBE)
-      // Noting to be done. Just set z_probe_is_active
+      // Noting to be done. Just set endstops.z_probe_enabled
     #endif
 
-    z_probe_is_active = true;
+    endstops.enable_z_probe();
 
   }
 
@@ -1793,7 +1790,7 @@ static void setup_for_endstop_move() {
       if (DEBUGGING(LEVELING)) DEBUG_POS("stow_z_probe", current_position);
     #endif
 
-    if (!z_probe_is_active) return;
+    if (!endstops.z_probe_enabled) return;
 
     #if HAS_SERVO_ENDSTOPS
 
@@ -1811,7 +1808,7 @@ static void setup_for_endstop_move() {
               }
             #endif
             raise_z_after_probing(); // this also updates current_position
-            st_synchronize();
+            stepper.synchronize();
           }
         #endif
 
@@ -1861,7 +1858,7 @@ static void setup_for_endstop_move() {
       destination[Y_AXIS] = 0;
       prepare_move_raw(); // this will also set_current_to_destination
 
-      st_synchronize();
+      stepper.synchronize();
 
       #if ENABLED(Z_MIN_PROBE_ENDSTOP)
         bool z_probe_endstop = (READ(Z_MIN_PROBE_PIN) != Z_MIN_PROBE_ENDSTOP_INVERTING);
@@ -1881,10 +1878,10 @@ static void setup_for_endstop_move() {
     #endif // Z_PROBE_ALLEN_KEY
 
     #if ENABLED(FIX_MOUNTED_PROBE)
-      // Nothing to do here. Just clear z_probe_is_active
+      // Nothing to do here. Just clear endstops.z_probe_enabled
     #endif
 
-    z_probe_is_active = false;
+    endstops.enable_z_probe(false);
   }
   #endif // HAS_Z_MIN_PROBE
 
@@ -2081,13 +2078,13 @@ static void setup_for_endstop_move() {
       }
     #endif
 
-    if (z_probe_is_active == dock) return;
-
     if (!axis_homed[X_AXIS] || !axis_homed[Y_AXIS]) {
       axis_unhomed_error();
       return;
     }
 
+    if (endstops.z_probe_enabled == !dock) return; // already docked/undocked?
+
     float oldXpos = current_position[X_AXIS]; // save x position
     if (dock) {
       #if Z_RAISE_AFTER_PROBING > 0
@@ -2105,7 +2102,7 @@ static void setup_for_endstop_move() {
     }
     do_blocking_move_to_x(oldXpos); // return to position before docking
 
-    z_probe_is_active = dock;
+    endstops.enable_z_probe(!dock); // logically disable docked probe
   }
 
 #endif // Z_PROBE_SLED
@@ -2167,39 +2164,39 @@ static void homeaxis(AxisEnum axis) {
       // Engage an X or Y Servo endstop if enabled
       if (_Z_SERVO_TEST && servo_endstop_id[axis] >= 0) {
         servo[servo_endstop_id[axis]].move(servo_endstop_angle[axis][0]);
-        if (_Z_PROBE_SUBTEST) z_probe_is_active = true;
+        if (_Z_PROBE_SUBTEST) endstops.z_probe_enabled = true;
       }
     #endif
 
     // Set a flag for Z motor locking
     #if ENABLED(Z_DUAL_ENDSTOPS)
-      if (axis == Z_AXIS) In_Homing_Process(true);
+      if (axis == Z_AXIS) stepper.set_homing_flag(true);
     #endif
 
     // Move towards the endstop until an endstop is triggered
     destination[axis] = 1.5 * max_length(axis) * axis_home_dir;
     feedrate = homing_feedrate[axis];
     line_to_destination();
-    st_synchronize();
+    stepper.synchronize();
 
     // Set the axis position as setup for the move
     current_position[axis] = 0;
     sync_plan_position();
 
     #if ENABLED(DEBUG_LEVELING_FEATURE)
-      if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> enable_endstops(false)");
+      if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> endstops.enable(false)");
     #endif
-    enable_endstops(false); // Disable endstops while moving away
+    endstops.enable(false); // Disable endstops while moving away
 
     // Move away from the endstop by the axis HOME_BUMP_MM
     destination[axis] = -home_bump_mm(axis) * axis_home_dir;
     line_to_destination();
-    st_synchronize();
+    stepper.synchronize();
 
     #if ENABLED(DEBUG_LEVELING_FEATURE)
-      if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> enable_endstops(true)");
+      if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> endstops.enable(true)");
     #endif
-    enable_endstops(true); // Enable endstops for next homing move
+    endstops.enable(true); // Enable endstops for next homing move
 
     // Slow down the feedrate for the next move
     set_homing_bump_feedrate(axis);
@@ -2207,7 +2204,7 @@ static void homeaxis(AxisEnum axis) {
     // Move slowly towards the endstop until triggered
     destination[axis] = 2 * home_bump_mm(axis) * axis_home_dir;
     line_to_destination();
-    st_synchronize();
+    stepper.synchronize();
 
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       if (DEBUGGING(LEVELING)) DEBUG_POS("> TRIGGER ENDSTOP", current_position);
@@ -2224,17 +2221,17 @@ static void homeaxis(AxisEnum axis) {
         else
           lockZ1 = (z_endstop_adj < 0);
 
-        if (lockZ1) Lock_z_motor(true); else Lock_z2_motor(true);
+        if (lockZ1) stepper.set_z_lock(true); else stepper.set_z2_lock(true);
         sync_plan_position();
 
         // Move to the adjusted endstop height
         feedrate = homing_feedrate[axis];
         destination[Z_AXIS] = adj;
         line_to_destination();
-        st_synchronize();
+        stepper.synchronize();
 
-        if (lockZ1) Lock_z_motor(false); else Lock_z2_motor(false);
-        In_Homing_Process(false);
+        if (lockZ1) stepper.set_z_lock(false); else stepper.set_z2_lock(false);
+        stepper.set_homing_flag(false);
       } // Z_AXIS
     #endif
 
@@ -2242,9 +2239,9 @@ static void homeaxis(AxisEnum axis) {
       // retrace by the amount specified in endstop_adj
       if (endstop_adj[axis] * axis_home_dir < 0) {
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> enable_endstops(false)");
+          if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> endstops.enable(false)");
         #endif
-        enable_endstops(false); // Disable endstops while moving away
+        endstops.enable(false); // Disable endstops while moving away
         sync_plan_position();
         destination[axis] = endstop_adj[axis];
         #if ENABLED(DEBUG_LEVELING_FEATURE)
@@ -2254,11 +2251,11 @@ static void homeaxis(AxisEnum axis) {
           }
         #endif
         line_to_destination();
-        st_synchronize();
+        stepper.synchronize();
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> enable_endstops(true)");
+          if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> endstops.enable(true)");
         #endif
-        enable_endstops(true); // Enable endstops for next homing move
+        endstops.enable(true); // Enable endstops for next homing move
       }
       #if ENABLED(DEBUG_LEVELING_FEATURE)
         else {
@@ -2280,7 +2277,7 @@ static void homeaxis(AxisEnum axis) {
 
     destination[axis] = current_position[axis];
     feedrate = 0.0;
-    endstops_hit_on_purpose(); // clear endstop hit flags
+    endstops.hit_on_purpose(); // clear endstop hit flags
     axis_known_position[axis] = true;
     axis_homed[axis] = true;
 
@@ -2301,7 +2298,7 @@ static void homeaxis(AxisEnum axis) {
           if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("> SERVO_ENDSTOPS > Stow with servo.move()");
         #endif
         servo[servo_endstop_id[axis]].move(servo_endstop_angle[axis][1]);
-        if (_Z_PROBE_SUBTEST) z_probe_is_active = false;
+        if (_Z_PROBE_SUBTEST) endstops.enable_z_probe(false);
       }
     #endif
 
@@ -2499,7 +2496,7 @@ inline void gcode_G4() {
   if (code_seen('P')) codenum = code_value_long(); // milliseconds to wait
   if (code_seen('S')) codenum = code_value() * 1000UL; // seconds to wait
 
-  st_synchronize();
+  stepper.synchronize();
   refresh_cmd_timeout();
   codenum += previous_cmd_ms;  // keep track of when we started waiting
 
@@ -2551,7 +2548,7 @@ inline void gcode_G28() {
   #endif
 
   // Wait for planner moves to finish!
-  st_synchronize();
+  stepper.synchronize();
 
   // For auto bed leveling, clear the level matrix
   #if ENABLED(AUTO_BED_LEVELING_FEATURE)
@@ -2594,8 +2591,8 @@ inline void gcode_G28() {
     for (int i = X_AXIS; i <= Z_AXIS; i++) destination[i] = 3 * (Z_MAX_LENGTH);
     feedrate = 1.732 * homing_feedrate[X_AXIS];
     line_to_destination();
-    st_synchronize();
-    endstops_hit_on_purpose(); // clear endstop hit flags
+    stepper.synchronize();
+    endstops.hit_on_purpose(); // clear endstop hit flags
 
     // Destination reached
     for (int i = X_AXIS; i <= Z_AXIS; i++) current_position[i] = destination[i];
@@ -2643,7 +2640,7 @@ inline void gcode_G28() {
           }
         #endif
         line_to_destination();
-        st_synchronize();
+        stepper.synchronize();
 
         /**
          * Update the current Z position even if it currently not real from
@@ -2676,7 +2673,7 @@ inline void gcode_G28() {
         destination[Y_AXIS] = 1.5 * mly * home_dir(Y_AXIS);
         feedrate = min(homing_feedrate[X_AXIS], homing_feedrate[Y_AXIS]) * sqrt(mlratio * mlratio + 1);
         line_to_destination();
-        st_synchronize();
+        stepper.synchronize();
 
         set_axis_is_at_home(X_AXIS);
         set_axis_is_at_home(Y_AXIS);
@@ -2690,8 +2687,8 @@ inline void gcode_G28() {
         destination[Y_AXIS] = current_position[Y_AXIS];
         line_to_destination();
         feedrate = 0.0;
-        st_synchronize();
-        endstops_hit_on_purpose(); // clear endstop hit flags
+        stepper.synchronize();
+        endstops.hit_on_purpose(); // clear endstop hit flags
 
         current_position[X_AXIS] = destination[X_AXIS];
         current_position[Y_AXIS] = destination[Y_AXIS];
@@ -2784,7 +2781,7 @@ inline void gcode_G28() {
 
             // Move in the XY plane
             line_to_destination();
-            st_synchronize();
+            stepper.synchronize();
 
             /**
              * Update the current positions for XY, Z is still at least at
@@ -2857,10 +2854,10 @@ inline void gcode_G28() {
   #endif
 
   #if ENABLED(ENDSTOPS_ONLY_FOR_HOMING)
-    enable_endstops(false);
+    endstops.enable(false);
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       if (DEBUGGING(LEVELING)) {
-        SERIAL_ECHOLNPGM("ENDSTOPS_ONLY_FOR_HOMING enable_endstops(false)");
+        SERIAL_ECHOLNPGM("ENDSTOPS_ONLY_FOR_HOMING endstops.enable(false)");
       }
     #endif
   #endif
@@ -2875,7 +2872,7 @@ inline void gcode_G28() {
       set_destination_to_current();
       feedrate = homing_feedrate[Z_AXIS];
       line_to_destination();
-      st_synchronize();
+      stepper.synchronize();
       #if ENABLED(DEBUG_LEVELING_FEATURE)
         if (DEBUGGING(LEVELING)) DEBUG_POS("mbl_was_active", current_position);
       #endif
@@ -2885,7 +2882,7 @@ inline void gcode_G28() {
   feedrate = saved_feedrate;
   feedrate_multiplier = saved_feedrate_multiplier;
   refresh_cmd_timeout();
-  endstops_hit_on_purpose(); // clear endstop hit flags
+  endstops.hit_on_purpose(); // clear endstop hit flags
 
   #if ENABLED(DEBUG_LEVELING_FEATURE)
     if (DEBUGGING(LEVELING)) {
@@ -2921,7 +2918,7 @@ inline void gcode_G28() {
     #endif
 
     feedrate = saved_feedrate;
-    st_synchronize();
+    stepper.synchronize();
   }
 
   /**
@@ -3015,7 +3012,7 @@ inline void gcode_G28() {
             #endif
           ;
           line_to_current_position();
-          st_synchronize();
+          stepper.synchronize();
 
           // After recording the last point, activate the mbl and home
           SERIAL_PROTOCOLLNPGM("Mesh probing done.");
@@ -3240,7 +3237,7 @@ inline void gcode_G28() {
       deploy_z_probe();
     #endif
 
-    st_synchronize();
+    stepper.synchronize();
 
     setup_for_endstop_move();
 
@@ -3511,7 +3508,7 @@ inline void gcode_G28() {
         float x_tmp = current_position[X_AXIS] + X_PROBE_OFFSET_FROM_EXTRUDER,
               y_tmp = current_position[Y_AXIS] + Y_PROBE_OFFSET_FROM_EXTRUDER,
               z_tmp = current_position[Z_AXIS],
-              real_z = st_get_axis_position_mm(Z_AXIS);  //get the real Z (since plan_get_position is now correcting the plane)
+              real_z = stepper.get_axis_position_mm(Z_AXIS);  //get the real Z (since plan_get_position is now correcting the plane)
 
         #if ENABLED(DEBUG_LEVELING_FEATURE)
           if (DEBUGGING(LEVELING)) {
@@ -3588,9 +3585,9 @@ inline void gcode_G28() {
       #endif
       enqueue_and_echo_commands_P(PSTR(Z_PROBE_END_SCRIPT));
       #if ENABLED(HAS_Z_MIN_PROBE)
-        z_probe_is_active = false;
+        endstops.enable_z_probe(false);
       #endif
-      st_synchronize();
+      stepper.synchronize();
     #endif
 
     KEEPALIVE_STATE(IN_HANDLER);
@@ -3615,7 +3612,7 @@ inline void gcode_G28() {
       #endif
       deploy_z_probe(); // Engage Z Servo endstop if available. Z_PROBE_SLED is missed here.
 
-      st_synchronize();
+      stepper.synchronize();
       // TODO: clear the leveling matrix or the planner will be set incorrectly
       setup_for_endstop_move(); // Too late. Must be done before deploying.
 
@@ -3650,7 +3647,7 @@ inline void gcode_G28() {
 inline void gcode_G92() {
   bool didE = code_seen(axis_codes[E_AXIS]);
 
-  if (!didE) st_synchronize();
+  if (!didE) stepper.synchronize();
 
   bool didXYZ = false;
   for (int i = 0; i < NUM_AXIS; i++) {
@@ -3712,7 +3709,7 @@ inline void gcode_G92() {
     }
 
     lcd_ignore_click();
-    st_synchronize();
+    stepper.synchronize();
     refresh_cmd_timeout();
     if (codenum > 0) {
       codenum += previous_cmd_ms;  // wait until this time for a click
@@ -3853,7 +3850,7 @@ inline void gcode_M31() {
    */
   inline void gcode_M32() {
     if (card.sdprinting)
-      st_synchronize();
+      stepper.synchronize();
 
     char* namestartpos = strchr(current_command_args, '!');  // Find ! to indicate filename string start.
     if (!namestartpos)
@@ -4819,7 +4816,7 @@ inline void gcode_M140() {
  */
 inline void gcode_M81() {
   disable_all_heaters();
-  finishAndDisableSteppers();
+  stepper.finish_and_disable();
   #if FAN_COUNT > 0
     #if FAN_COUNT > 1
       for (uint8_t i = 0; i < FAN_COUNT; i++) fanSpeeds[i] = 0;
@@ -4829,7 +4826,7 @@ inline void gcode_M81() {
   #endif
   delay(1000); // Wait 1 second before switching off
   #if HAS_SUICIDE
-    st_synchronize();
+    stepper.synchronize();
     suicide();
   #elif HAS_POWER_SWITCH
     OUT_WRITE(PS_ON_PIN, PS_ON_ASLEEP);
@@ -4864,10 +4861,10 @@ inline void gcode_M18_M84() {
   else {
     bool all_axis = !((code_seen(axis_codes[X_AXIS])) || (code_seen(axis_codes[Y_AXIS])) || (code_seen(axis_codes[Z_AXIS])) || (code_seen(axis_codes[E_AXIS])));
     if (all_axis) {
-      finishAndDisableSteppers();
+      stepper.finish_and_disable();
     }
     else {
-      st_synchronize();
+      stepper.synchronize();
       if (code_seen('X')) disable_x();
       if (code_seen('Y')) disable_y();
       if (code_seen('Z')) disable_z();
@@ -4927,35 +4924,7 @@ static void report_current_position() {
   SERIAL_PROTOCOLPGM(" E:");
   SERIAL_PROTOCOL(current_position[E_AXIS]);
 
-  CRITICAL_SECTION_START;
-  extern volatile long count_position[NUM_AXIS];
-  long xpos = count_position[X_AXIS],
-       ypos = count_position[Y_AXIS],
-       zpos = count_position[Z_AXIS];
-  CRITICAL_SECTION_END;
-
-  #if ENABLED(COREXY) || ENABLED(COREXZ)
-    SERIAL_PROTOCOLPGM(MSG_COUNT_A);
-  #else
-    SERIAL_PROTOCOLPGM(MSG_COUNT_X);
-  #endif
-  SERIAL_PROTOCOL(xpos);
-
-  #if ENABLED(COREXY)
-    SERIAL_PROTOCOLPGM(" B:");
-  #else
-    SERIAL_PROTOCOLPGM(" Y:");
-  #endif
-  SERIAL_PROTOCOL(ypos);
-
-  #if ENABLED(COREXZ)
-    SERIAL_PROTOCOLPGM(" C:");
-  #else
-    SERIAL_PROTOCOLPGM(" Z:");
-  #endif
-  SERIAL_PROTOCOL(zpos);
-
-  SERIAL_EOL;
+  stepper.report_positions();
 
   #if ENABLED(SCARA)
     SERIAL_PROTOCOLPGM("SCARA Theta:");
@@ -5039,12 +5008,12 @@ inline void gcode_M119() {
 /**
  * M120: Enable endstops and set non-homing endstop state to "enabled"
  */
-inline void gcode_M120() { enable_endstops_globally(true); }
+inline void gcode_M120() { endstops.enable_globally(true); }
 
 /**
  * M121: Disable endstops and set non-homing endstop state to "disabled"
  */
-inline void gcode_M121() { enable_endstops_globally(false); }
+inline void gcode_M121() { endstops.enable_globally(false); }
 
 #if ENABLED(BLINKM)
 
@@ -5439,7 +5408,7 @@ inline void gcode_M226() {
       if (pin_number > -1) {
         int target = LOW;
 
-        st_synchronize();
+        stepper.synchronize();
 
         pinMode(pin_number, INPUT);
 
@@ -5801,7 +5770,7 @@ inline void gcode_M303() {
 /**
  * M400: Finish all moves
  */
-inline void gcode_M400() { st_synchronize(); }
+inline void gcode_M400() { stepper.synchronize(); }
 
 #if ENABLED(AUTO_BED_LEVELING_FEATURE) && DISABLED(Z_PROBE_SLED) && (HAS_SERVO_ENDSTOPS || ENABLED(Z_PROBE_ALLEN_KEY))
 
@@ -5887,7 +5856,7 @@ inline void gcode_M400() { st_synchronize(); }
  * This will stop the carriages mid-move, so most likely they
  * will be out of sync with the stepper position after this.
  */
-inline void gcode_M410() { quickStop(); }
+inline void gcode_M410() { stepper.quick_stop(); }
 
 
 #if ENABLED(MESH_BED_LEVELING)
@@ -6111,7 +6080,7 @@ inline void gcode_M503() {
     RUNPLAN;
 
     //finish moves
-    st_synchronize();
+    stepper.synchronize();
     //disable extruder steppers so filament can be removed
     disable_e0();
     disable_e1();
@@ -6135,7 +6104,7 @@ inline void gcode_M503() {
         current_position[E_AXIS] += AUTO_FILAMENT_CHANGE_LENGTH;
         destination[E_AXIS] = current_position[E_AXIS];
         line_to_destination(AUTO_FILAMENT_CHANGE_FEEDRATE);
-        st_synchronize();
+        stepper.synchronize();
       #endif
     } // while(!lcd_clicked)
     KEEPALIVE_STATE(IN_HANDLER);
@@ -6143,7 +6112,7 @@ inline void gcode_M503() {
 
     #if ENABLED(AUTO_FILAMENT_CHANGE)
       current_position[E_AXIS] = 0;
-      st_synchronize();
+      stepper.synchronize();
     #endif
 
     //return to normal
@@ -6198,7 +6167,7 @@ inline void gcode_M503() {
    *    Note: the X axis should be homed after changing dual x-carriage mode.
    */
   inline void gcode_M605() {
-    st_synchronize();
+    stepper.synchronize();
     if (code_seen('S')) dual_x_carriage_mode = code_value();
     switch (dual_x_carriage_mode) {
       case DXC_DUPLICATION_MODE:
@@ -6375,7 +6344,7 @@ inline void gcode_T(uint8_t tmp_extruder) {
                            current_position[E_AXIS], max_feedrate[X_AXIS], active_extruder);
           plan_buffer_line(x_home_pos(active_extruder), current_position[Y_AXIS], current_position[Z_AXIS],
                            current_position[E_AXIS], max_feedrate[Z_AXIS], active_extruder);
-          st_synchronize();
+          stepper.synchronize();
         }
 
         // apply Y & Z extruder offset (x offset is already used in determining home pos)
@@ -6460,7 +6429,7 @@ inline void gcode_T(uint8_t tmp_extruder) {
     } // (tmp_extruder != active_extruder)
 
     #if ENABLED(EXT_SOLENOID)
-      st_synchronize();
+      stepper.synchronize();
       disable_all_solenoids();
       enable_solenoid_on_active_extruder();
     #endif // EXT_SOLENOID
@@ -7400,7 +7369,7 @@ void mesh_plan_buffer_line(float x, float y, float z, const float e, float feed_
         plan_buffer_line(current_position[X_AXIS] + duplicate_extruder_x_offset,
                          current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], max_feedrate[X_AXIS], 1);
         sync_plan_position();
-        st_synchronize();
+        stepper.synchronize();
         extruder_duplication_enabled = true;
         active_extruder_parked = false;
       }
@@ -7927,7 +7896,7 @@ void manage_inactivity(bool ignore_stepper_queue/*=false*/) {
       destination[E_AXIS] = oldedes;
       plan_set_e_position(oldepos);
       previous_cmd_ms = ms; // refresh_cmd_timeout()
-      st_synchronize();
+      stepper.synchronize();
       switch (active_extruder) {
         case 0:
           E0_ENABLE_WRITE(oldstatus);
@@ -8004,7 +7973,7 @@ void kill(const char* lcd_msg) {
     if (!filament_ran_out) {
       filament_ran_out = true;
       enqueue_and_echo_commands_P(PSTR(FILAMENT_RUNOUT_SCRIPT));
-      st_synchronize();
+      stepper.synchronize();
     }
   }
 
diff --git a/Marlin/cardreader.cpp b/Marlin/cardreader.cpp
index fbe4ae7e70..1e9aab3b66 100644
--- a/Marlin/cardreader.cpp
+++ b/Marlin/cardreader.cpp
@@ -596,7 +596,7 @@ void CardReader::updir() {
 }
 
 void CardReader::printingHasFinished() {
-  st_synchronize();
+  stepper.synchronize();
   if (file_subcall_ctr > 0) { // Heading up to a parent file that called current as a procedure.
     file.close();
     file_subcall_ctr--;
diff --git a/Marlin/endstops.cpp b/Marlin/endstops.cpp
new file mode 100644
index 0000000000..e3d5f4b827
--- /dev/null
+++ b/Marlin/endstops.cpp
@@ -0,0 +1,317 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/**
+ * endstops.cpp - A singleton object to manage endstops
+ */
+
+#include "Marlin.h"
+#include "endstops.h"
+#include "stepper.h"
+#include "ultralcd.h"
+
+// TEST_ENDSTOP: test the old and the current status of an endstop
+#define TEST_ENDSTOP(ENDSTOP) (TEST(current_endstop_bits & old_endstop_bits, ENDSTOP))
+
+Endstops endstops;
+
+Endstops::Endstops() {
+  enable_globally(ENABLED(ENDSTOPS_ONLY_FOR_HOMING));
+  enable(true);
+  #if ENABLED(HAS_Z_MIN_PROBE)
+    enable_z_probe(false);
+  #endif
+} // Endstops::Endstops
+
+void Endstops::init() {
+
+  #if HAS_X_MIN
+    SET_INPUT(X_MIN_PIN);
+    #if ENABLED(ENDSTOPPULLUP_XMIN)
+      WRITE(X_MIN_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Y_MIN
+    SET_INPUT(Y_MIN_PIN);
+    #if ENABLED(ENDSTOPPULLUP_YMIN)
+      WRITE(Y_MIN_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Z_MIN
+    SET_INPUT(Z_MIN_PIN);
+    #if ENABLED(ENDSTOPPULLUP_ZMIN)
+      WRITE(Z_MIN_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Z2_MIN
+    SET_INPUT(Z2_MIN_PIN);
+    #if ENABLED(ENDSTOPPULLUP_ZMIN)
+      WRITE(Z2_MIN_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_X_MAX
+    SET_INPUT(X_MAX_PIN);
+    #if ENABLED(ENDSTOPPULLUP_XMAX)
+      WRITE(X_MAX_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Y_MAX
+    SET_INPUT(Y_MAX_PIN);
+    #if ENABLED(ENDSTOPPULLUP_YMAX)
+      WRITE(Y_MAX_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Z_MAX
+    SET_INPUT(Z_MAX_PIN);
+    #if ENABLED(ENDSTOPPULLUP_ZMAX)
+      WRITE(Z_MAX_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Z2_MAX
+    SET_INPUT(Z2_MAX_PIN);
+    #if ENABLED(ENDSTOPPULLUP_ZMAX)
+      WRITE(Z2_MAX_PIN,HIGH);
+    #endif
+  #endif
+
+  #if HAS_Z_PROBE && ENABLED(Z_MIN_PROBE_ENDSTOP) // Check for Z_MIN_PROBE_ENDSTOP so we don't pull a pin high unless it's to be used.
+    SET_INPUT(Z_MIN_PROBE_PIN);
+    #if ENABLED(ENDSTOPPULLUP_ZMIN_PROBE)
+      WRITE(Z_MIN_PROBE_PIN,HIGH);
+    #endif
+  #endif
+
+} // Endstops::init
+
+void Endstops::report_state() {
+  if (endstop_hit_bits) {
+    #if ENABLED(ULTRA_LCD)
+      char chrX = ' ', chrY = ' ', chrZ = ' ', chrP = ' ';
+      #define _SET_STOP_CHAR(A,C) (chr## A = C)
+    #else
+      #define _SET_STOP_CHAR(A,C) ;
+    #endif
+
+    #define _ENDSTOP_HIT_ECHO(A,C) do{ \
+      SERIAL_ECHOPAIR(" " STRINGIFY(A) ":", stepper.triggered_position_mm(A ##_AXIS)); \
+      _SET_STOP_CHAR(A,C); }while(0)
+
+    #define _ENDSTOP_HIT_TEST(A,C) \
+      if (TEST(endstop_hit_bits, A ##_MIN) || TEST(endstop_hit_bits, A ##_MAX)) \
+        _ENDSTOP_HIT_ECHO(A,C)
+
+    SERIAL_ECHO_START;
+    SERIAL_ECHOPGM(MSG_ENDSTOPS_HIT);
+    _ENDSTOP_HIT_TEST(X, 'X');
+    _ENDSTOP_HIT_TEST(Y, 'Y');
+    _ENDSTOP_HIT_TEST(Z, 'Z');
+
+    #if ENABLED(Z_MIN_PROBE_ENDSTOP)
+      #define P_AXIS Z_AXIS
+      if (TEST(endstop_hit_bits, Z_MIN_PROBE)) _ENDSTOP_HIT_ECHO(P, 'P');
+    #endif
+    SERIAL_EOL;
+
+    #if ENABLED(ULTRA_LCD)
+      char msg[3 * strlen(MSG_LCD_ENDSTOPS) + 8 + 1]; // Room for a UTF 8 string
+      sprintf_P(msg, PSTR(MSG_LCD_ENDSTOPS " %c %c %c %c"), chrX, chrY, chrZ, chrP);
+      lcd_setstatus(msg);
+    #endif
+
+    hit_on_purpose();
+
+    #if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED) && ENABLED(SDSUPPORT)
+      if (abort_on_endstop_hit) {
+        card.sdprinting = false;
+        card.closefile();
+        stepper.quick_stop();
+        disable_all_heaters(); // switch off all heaters.
+      }
+    #endif
+  }
+} // Endstops::report_state
+
+// Check endstops - Called from ISR!
+void Endstops::update() {
+
+  #define _ENDSTOP_PIN(AXIS, MINMAX) AXIS ##_## MINMAX ##_PIN
+  #define _ENDSTOP_INVERTING(AXIS, MINMAX) AXIS ##_## MINMAX ##_ENDSTOP_INVERTING
+  #define _ENDSTOP_HIT(AXIS) SBI(endstop_hit_bits, _ENDSTOP(AXIS, MIN))
+  #define _ENDSTOP(AXIS, MINMAX) AXIS ##_## MINMAX
+
+  // UPDATE_ENDSTOP_BIT: set the current endstop bits for an endstop to its status
+  #define UPDATE_ENDSTOP_BIT(AXIS, MINMAX) SET_BIT(current_endstop_bits, _ENDSTOP(AXIS, MINMAX), (READ(_ENDSTOP_PIN(AXIS, MINMAX)) != _ENDSTOP_INVERTING(AXIS, MINMAX)))
+  // COPY_BIT: copy the value of COPY_BIT to BIT in bits
+  #define COPY_BIT(bits, COPY_BIT, BIT) SET_BIT(bits, BIT, TEST(bits, COPY_BIT))
+
+  #define UPDATE_ENDSTOP(AXIS,MINMAX) do { \
+      UPDATE_ENDSTOP_BIT(AXIS, MINMAX); \
+      if (TEST_ENDSTOP(_ENDSTOP(AXIS, MINMAX)) && stepper.current_block->steps[_AXIS(AXIS)] > 0) { \
+        _ENDSTOP_HIT(AXIS); \
+        stepper.endstop_triggered(_AXIS(AXIS)); \
+      } \
+    } while(0)
+
+  #if ENABLED(COREXY) || ENABLED(COREXZ)
+    // Head direction in -X axis for CoreXY and CoreXZ bots.
+    // If Delta1 == -Delta2, the movement is only in Y or Z axis
+    if ((stepper.current_block->steps[A_AXIS] != stepper.current_block->steps[CORE_AXIS_2]) || (stepper.motor_direction(A_AXIS) == stepper.motor_direction(CORE_AXIS_2))) {
+      if (stepper.motor_direction(X_HEAD))
+  #else
+    if (stepper.motor_direction(X_AXIS))   // stepping along -X axis (regular Cartesian bot)
+  #endif
+      { // -direction
+        #if ENABLED(DUAL_X_CARRIAGE)
+          // with 2 x-carriages, endstops are only checked in the homing direction for the active extruder
+          if ((stepper.current_block->active_extruder == 0 && X_HOME_DIR == -1) || (stepper.current_block->active_extruder != 0 && X2_HOME_DIR == -1))
+        #endif
+          {
+            #if HAS_X_MIN
+              UPDATE_ENDSTOP(X, MIN);
+            #endif
+          }
+      }
+      else { // +direction
+        #if ENABLED(DUAL_X_CARRIAGE)
+          // with 2 x-carriages, endstops are only checked in the homing direction for the active extruder
+          if ((stepper.current_block->active_extruder == 0 && X_HOME_DIR == 1) || (stepper.current_block->active_extruder != 0 && X2_HOME_DIR == 1))
+        #endif
+          {
+            #if HAS_X_MAX
+              UPDATE_ENDSTOP(X, MAX);
+            #endif
+          }
+      }
+  #if ENABLED(COREXY) || ENABLED(COREXZ)
+    }
+  #endif
+
+  #if ENABLED(COREXY)
+    // Head direction in -Y axis for CoreXY bots.
+    // If DeltaX == DeltaY, the movement is only in X axis
+    if ((stepper.current_block->steps[A_AXIS] != stepper.current_block->steps[B_AXIS]) || (stepper.motor_direction(A_AXIS) != stepper.motor_direction(B_AXIS))) {
+      if (stepper.motor_direction(Y_HEAD))
+  #else
+      if (stepper.motor_direction(Y_AXIS))   // -direction
+  #endif
+      { // -direction
+        #if HAS_Y_MIN
+          UPDATE_ENDSTOP(Y, MIN);
+        #endif
+      }
+      else { // +direction
+        #if HAS_Y_MAX
+          UPDATE_ENDSTOP(Y, MAX);
+        #endif
+      }
+  #if ENABLED(COREXY)
+    }
+  #endif
+
+  #if ENABLED(COREXZ)
+    // Head direction in -Z axis for CoreXZ bots.
+    // If DeltaX == DeltaZ, the movement is only in X axis
+    if ((stepper.current_block->steps[A_AXIS] != stepper.current_block->steps[C_AXIS]) || (stepper.motor_direction(A_AXIS) != stepper.motor_direction(C_AXIS))) {
+      if (stepper.motor_direction(Z_HEAD))
+  #else
+      if (stepper.motor_direction(Z_AXIS))
+  #endif
+      { // z -direction
+        #if HAS_Z_MIN
+
+          #if ENABLED(Z_DUAL_ENDSTOPS)
+
+            UPDATE_ENDSTOP_BIT(Z, MIN);
+            #if HAS_Z2_MIN
+              UPDATE_ENDSTOP_BIT(Z2, MIN);
+            #else
+              COPY_BIT(current_endstop_bits, Z_MIN, Z2_MIN);
+            #endif
+
+            byte z_test = TEST_ENDSTOP(Z_MIN) | (TEST_ENDSTOP(Z2_MIN) << 1); // bit 0 for Z, bit 1 for Z2
+
+            if (z_test && stepper.current_block->steps[Z_AXIS] > 0) { // z_test = Z_MIN || Z2_MIN
+              stepper.endstop_triggered(Z_AXIS);
+              SBI(endstop_hit_bits, Z_MIN);
+              if (!performing_homing || (z_test == 0x3))  //if not performing home or if both endstops were trigged during homing...
+                stepper.kill_current_block();
+            }
+
+          #else // !Z_DUAL_ENDSTOPS
+
+            #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
+              if (z_probe_enabled) UPDATE_ENDSTOP(Z, MIN);
+            #else
+              UPDATE_ENDSTOP(Z, MIN);
+            #endif
+
+          #endif // !Z_DUAL_ENDSTOPS
+
+        #endif // HAS_Z_MIN
+
+        #if ENABLED(Z_MIN_PROBE_ENDSTOP) && DISABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
+          if (z_probe_enabled) {
+            UPDATE_ENDSTOP(Z, MIN_PROBE);
+            if (TEST_ENDSTOP(Z_MIN_PROBE)) SBI(endstop_hit_bits, Z_MIN_PROBE);
+          }
+        #endif
+      }
+      else { // z +direction
+        #if HAS_Z_MAX
+
+          #if ENABLED(Z_DUAL_ENDSTOPS)
+
+            UPDATE_ENDSTOP_BIT(Z, MAX);
+            #if HAS_Z2_MAX
+              UPDATE_ENDSTOP_BIT(Z2, MAX);
+            #else
+              COPY_BIT(current_endstop_bits, Z_MAX, Z2_MAX);
+            #endif
+
+            byte z_test = TEST_ENDSTOP(Z_MAX) | (TEST_ENDSTOP(Z2_MAX) << 1); // bit 0 for Z, bit 1 for Z2
+
+            if (z_test && stepper.current_block->steps[Z_AXIS] > 0) {  // t_test = Z_MAX || Z2_MAX
+              stepper.endstop_triggered(Z_AXIS);
+              SBI(endstop_hit_bits, Z_MIN);
+              if (!performing_homing || (z_test == 0x3))  //if not performing home or if both endstops were trigged during homing...
+                stepper.kill_current_block();
+            }
+
+          #else // !Z_DUAL_ENDSTOPS
+
+            UPDATE_ENDSTOP(Z, MAX);
+
+          #endif // !Z_DUAL_ENDSTOPS
+        #endif // Z_MAX_PIN
+      }
+  #if ENABLED(COREXZ)
+    }
+  #endif
+  old_endstop_bits = current_endstop_bits;
+} // Endstops::update()
diff --git a/Marlin/endstops.h b/Marlin/endstops.h
new file mode 100644
index 0000000000..4cf6f5b088
--- /dev/null
+++ b/Marlin/endstops.h
@@ -0,0 +1,94 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/**
+ *  endstops.h - manages endstops
+ */
+
+#ifndef ENDSTOPS_H
+#define ENDSTOPS_H
+
+enum EndstopEnum {X_MIN = 0, Y_MIN = 1, Z_MIN = 2, Z_MIN_PROBE = 3, X_MAX = 4, Y_MAX = 5, Z_MAX = 6, Z2_MIN = 7, Z2_MAX = 8};
+
+class Endstops {
+
+  public:
+
+    volatile char endstop_hit_bits; // use X_MIN, Y_MIN, Z_MIN and Z_MIN_PROBE as BIT value
+
+    #if ENABLED(Z_DUAL_ENDSTOPS)
+      uint16_t current_endstop_bits = 0,
+                   old_endstop_bits = 0;
+    #else
+      byte current_endstop_bits = 0,
+               old_endstop_bits = 0;
+    #endif
+        
+
+    bool enabled = true;
+    bool enabled_globally =
+      #if ENABLED(ENDSTOPS_ONLY_FOR_HOMING)
+        false
+      #else
+        true
+      #endif
+    ;
+
+    Endstops();
+
+    /**
+     * Initialize the endstop pins
+     */
+    void init();
+
+    /**
+     * Update the endstops bits from the pins
+     */
+    void update();
+
+    /**
+     * Print an error message reporting the position when the endstops were last hit.
+     */
+    void report_state(); //call from somewhere to create an serial error message with the locations the endstops where hit, in case they were triggered
+
+    // Enable / disable endstop checking globally
+    FORCE_INLINE void enable_globally(bool onoff=true) { enabled_globally = enabled = onoff; }
+
+    // Enable / disable endstop checking
+    FORCE_INLINE void enable(bool onoff=true) { enabled = onoff; }
+
+    // Disable / Enable endstops based on ENSTOPS_ONLY_FOR_HOMING and global enable
+    FORCE_INLINE void not_homing() { enabled = enabled_globally; }
+
+    // Clear endstops (i.e., they were hit intentionally) to suppress the report
+    FORCE_INLINE void hit_on_purpose() { endstop_hit_bits = 0; }
+
+    // Enable / disable endstop z-probe checking
+    #if ENABLED(HAS_Z_MIN_PROBE)
+      volatile bool z_probe_enabled = false;
+      FORCE_INLINE void enable_z_probe(bool onoff=true) { z_probe_enabled = onoff; }
+    #endif
+};
+
+extern Endstops endstops;
+
+#endif // ENDSTOPS_H
diff --git a/Marlin/planner.cpp b/Marlin/planner.cpp
index f5062d2a7d..9347744a58 100644
--- a/Marlin/planner.cpp
+++ b/Marlin/planner.cpp
@@ -1085,7 +1085,7 @@ float junction_deviation = 0.1;
 
   planner_recalculate();
 
-  st_wake_up();
+  stepper.wake_up();
 
 } // plan_buffer_line()
 
@@ -1097,7 +1097,7 @@ float junction_deviation = 0.1;
    * On CORE machines XYZ is derived from ABC.
    */
   vector_3 plan_get_position() {
-    vector_3 position = vector_3(st_get_axis_position_mm(X_AXIS), st_get_axis_position_mm(Y_AXIS), st_get_axis_position_mm(Z_AXIS));
+    vector_3 position = vector_3(stepper.get_axis_position_mm(X_AXIS), stepper.get_axis_position_mm(Y_AXIS), stepper.get_axis_position_mm(Z_AXIS));
 
     //position.debug("in plan_get position");
     //plan_bed_level_matrix.debug("in plan_get_position");
@@ -1132,7 +1132,7 @@ float junction_deviation = 0.1;
          ny = position[Y_AXIS] = lround(y * axis_steps_per_unit[Y_AXIS]),
          nz = position[Z_AXIS] = lround(z * axis_steps_per_unit[Z_AXIS]),
          ne = position[E_AXIS] = lround(e * axis_steps_per_unit[E_AXIS]);
-    st_set_position(nx, ny, nz, ne);
+    stepper.set_position(nx, ny, nz, ne);
     previous_nominal_speed = 0.0; // Resets planner junction speeds. Assumes start from rest.
 
     for (int i = 0; i < NUM_AXIS; i++) previous_speed[i] = 0.0;
@@ -1140,7 +1140,7 @@ float junction_deviation = 0.1;
 
 void plan_set_e_position(const float& e) {
   position[E_AXIS] = lround(e * axis_steps_per_unit[E_AXIS]);
-  st_set_e_position(position[E_AXIS]);
+  stepper.set_e_position(position[E_AXIS]);
 }
 
 // Calculate the steps/s^2 acceleration rates, based on the mm/s^s
diff --git a/Marlin/stepper.cpp b/Marlin/stepper.cpp
index 4b52edac9b..d3fa2b6375 100644
--- a/Marlin/stepper.cpp
+++ b/Marlin/stepper.cpp
@@ -21,7 +21,7 @@
  */
 
 /**
- * stepper.cpp - stepper motor driver: executes motion plans using stepper motors
+ * stepper.cpp - A singleton object to execute motion plans using stepper motors
  * Marlin Firmware
  *
  * Derived from Grbl
@@ -46,6 +46,7 @@
 
 #include "Marlin.h"
 #include "stepper.h"
+#include "endstops.h"
 #include "planner.h"
 #include "temperature.h"
 #include "ultralcd.h"
@@ -57,85 +58,7 @@
   #include <SPI.h>
 #endif
 
-//===========================================================================
-//============================= public variables ============================
-//===========================================================================
-block_t* current_block;  // A pointer to the block currently being traced
-
-#if ENABLED(HAS_Z_MIN_PROBE)
-  volatile bool z_probe_is_active = false;
-#endif
-
-//===========================================================================
-//============================= private variables ===========================
-//===========================================================================
-//static makes it impossible to be called from outside of this file by extern.!
-
-// Variables used by The Stepper Driver Interrupt
-static unsigned char out_bits = 0;        // The next stepping-bits to be output
-static unsigned int cleaning_buffer_counter;
-
-#if ENABLED(Z_DUAL_ENDSTOPS)
-  static bool performing_homing = false,
-              locked_z_motor = false,
-              locked_z2_motor = false;
-#endif
-
-// Counter variables for the Bresenham line tracer
-static long counter_x, counter_y, counter_z, counter_e;
-volatile static unsigned long step_events_completed; // The number of step events executed in the current block
-
-#if ENABLED(ADVANCE)
-  static long advance_rate, advance, final_advance = 0;
-  static long old_advance = 0;
-  static long e_steps[4];
-#endif
-
-static long acceleration_time, deceleration_time;
-//static unsigned long accelerate_until, decelerate_after, acceleration_rate, initial_rate, final_rate, nominal_rate;
-static unsigned short acc_step_rate; // needed for deceleration start point
-static uint8_t step_loops;
-static uint8_t step_loops_nominal;
-static unsigned short OCR1A_nominal;
-
-volatile long endstops_trigsteps[3] = { 0 };
-volatile long endstops_stepsTotal, endstops_stepsDone;
-static volatile char endstop_hit_bits = 0; // use X_MIN, Y_MIN, Z_MIN and Z_MIN_PROBE as BIT value
-
-#if DISABLED(Z_DUAL_ENDSTOPS)
-  static byte
-#else
-  static uint16_t
-#endif
-    old_endstop_bits = 0; // use X_MIN, X_MAX... Z_MAX, Z_MIN_PROBE, Z2_MIN, Z2_MAX
-
-#if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
-  bool abort_on_endstop_hit = false;
-#endif
-
-#if HAS_MOTOR_CURRENT_PWM
-  #ifndef PWM_MOTOR_CURRENT
-    #define PWM_MOTOR_CURRENT DEFAULT_PWM_MOTOR_CURRENT
-  #endif
-  const int motor_current_setting[3] = PWM_MOTOR_CURRENT;
-#endif
-
-static bool check_endstops = true;
-static bool check_endstops_global =
-  #if ENABLED(ENDSTOPS_ONLY_FOR_HOMING)
-    false
-  #else
-    true
-  #endif
-;
-
-volatile long count_position[NUM_AXIS] = { 0 }; // Positions of stepper motors, in step units
-volatile signed char count_direction[NUM_AXIS] = { 1 };
-
-
-//===========================================================================
-//================================ functions ================================
-//===========================================================================
+Stepper stepper; // Singleton
 
 #if ENABLED(DUAL_X_CARRIAGE)
   #define X_APPLY_DIR(v,ALWAYS) \
@@ -173,12 +96,12 @@ volatile signed char count_direction[NUM_AXIS] = { 1 };
     #define Z_APPLY_STEP(v,Q) \
     if (performing_homing) { \
       if (Z_HOME_DIR > 0) {\
-        if (!(TEST(old_endstop_bits, Z_MAX) && (count_direction[Z_AXIS] > 0)) && !locked_z_motor) Z_STEP_WRITE(v); \
-        if (!(TEST(old_endstop_bits, Z2_MAX) && (count_direction[Z_AXIS] > 0)) && !locked_z2_motor) Z2_STEP_WRITE(v); \
+        if (!(TEST(endstops.old_endstop_bits, Z_MAX) && (count_direction[Z_AXIS] > 0)) && !locked_z_motor) Z_STEP_WRITE(v); \
+        if (!(TEST(endstops.old_endstop_bits, Z2_MAX) && (count_direction[Z_AXIS] > 0)) && !locked_z2_motor) Z2_STEP_WRITE(v); \
       } \
       else { \
-        if (!(TEST(old_endstop_bits, Z_MIN) && (count_direction[Z_AXIS] < 0)) && !locked_z_motor) Z_STEP_WRITE(v); \
-        if (!(TEST(old_endstop_bits, Z2_MIN) && (count_direction[Z_AXIS] < 0)) && !locked_z2_motor) Z2_STEP_WRITE(v); \
+        if (!(TEST(endstops.old_endstop_bits, Z_MIN) && (count_direction[Z_AXIS] < 0)) && !locked_z_motor) Z_STEP_WRITE(v); \
+        if (!(TEST(endstops.old_endstop_bits, Z2_MIN) && (count_direction[Z_AXIS] < 0)) && !locked_z2_motor) Z2_STEP_WRITE(v); \
       } \
     } \
     else { \
@@ -195,31 +118,6 @@ volatile signed char count_direction[NUM_AXIS] = { 1 };
 
 #define E_APPLY_STEP(v,Q) E_STEP_WRITE(v)
 
-// intRes = intIn1 * intIn2 >> 16
-// uses:
-// r26 to store 0
-// r27 to store the byte 1 of the 24 bit result
-#define MultiU16X8toH16(intRes, charIn1, intIn2) \
-  asm volatile ( \
-                 "clr r26 \n\t" \
-                 "mul %A1, %B2 \n\t" \
-                 "movw %A0, r0 \n\t" \
-                 "mul %A1, %A2 \n\t" \
-                 "add %A0, r1 \n\t" \
-                 "adc %B0, r26 \n\t" \
-                 "lsr r0 \n\t" \
-                 "adc %A0, r26 \n\t" \
-                 "adc %B0, r26 \n\t" \
-                 "clr r1 \n\t" \
-                 : \
-                 "=&r" (intRes) \
-                 : \
-                 "d" (charIn1), \
-                 "d" (intIn2) \
-                 : \
-                 "r26" \
-               )
-
 // intRes = longIn1 * longIn2 >> 24
 // uses:
 // r26 to store 0
@@ -281,312 +179,38 @@ volatile signed char count_direction[NUM_AXIS] = { 1 };
 #define ENABLE_STEPPER_DRIVER_INTERRUPT()  SBI(TIMSK1, OCIE1A)
 #define DISABLE_STEPPER_DRIVER_INTERRUPT() CBI(TIMSK1, OCIE1A)
 
-void enable_endstops(bool check) { check_endstops = check; }
-
-void enable_endstops_globally(bool check) { check_endstops_global = check_endstops = check; }
-
-void endstops_not_homing() { check_endstops = check_endstops_global; }
-
-void endstops_hit_on_purpose() { endstop_hit_bits = 0; }
-
-void checkHitEndstops() {
-  if (endstop_hit_bits) {
-    #if ENABLED(ULTRA_LCD)
-      char chrX = ' ', chrY = ' ', chrZ = ' ', chrP = ' ';
-      #define _SET_STOP_CHAR(A,C) (chr## A = C)
-    #else
-      #define _SET_STOP_CHAR(A,C) ;
-    #endif
-
-    #define _ENDSTOP_HIT_ECHO(A,C) do{ \
-      SERIAL_ECHOPAIR(" " STRINGIFY(A) ":", endstops_trigsteps[A ##_AXIS] / axis_steps_per_unit[A ##_AXIS]); \
-      _SET_STOP_CHAR(A,C); }while(0)
-
-    #define _ENDSTOP_HIT_TEST(A,C) \
-      if (TEST(endstop_hit_bits, A ##_MIN) || TEST(endstop_hit_bits, A ##_MAX)) \
-        _ENDSTOP_HIT_ECHO(A,C)
-
-    SERIAL_ECHO_START;
-    SERIAL_ECHOPGM(MSG_ENDSTOPS_HIT);
-    _ENDSTOP_HIT_TEST(X, 'X');
-    _ENDSTOP_HIT_TEST(Y, 'Y');
-    _ENDSTOP_HIT_TEST(Z, 'Z');
-
-    #if ENABLED(Z_MIN_PROBE_ENDSTOP)
-      #define P_AXIS Z_AXIS
-      if (TEST(endstop_hit_bits, Z_MIN_PROBE)) _ENDSTOP_HIT_ECHO(P, 'P');
-    #endif
-    SERIAL_EOL;
-
-    #if ENABLED(ULTRA_LCD)
-      char msg[3 * strlen(MSG_LCD_ENDSTOPS) + 8 + 1]; // Room for a UTF 8 string
-      sprintf_P(msg, PSTR(MSG_LCD_ENDSTOPS " %c %c %c %c"), chrX, chrY, chrZ, chrP);
-      lcd_setstatus(msg);
-    #endif
-
-    endstops_hit_on_purpose();
-
-    #if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED) && ENABLED(SDSUPPORT)
-      if (abort_on_endstop_hit) {
-        card.sdprinting = false;
-        card.closefile();
-        quickStop();
-        disable_all_heaters(); // switch off all heaters.
-      }
-    #endif
-  }
-}
-
-// Check endstops - Called from ISR!
-inline void update_endstops() {
-
-  #if ENABLED(Z_DUAL_ENDSTOPS)
-    uint16_t
-  #else
-    byte
-  #endif
-      current_endstop_bits = 0;
-
-  #define _ENDSTOP_PIN(AXIS, MINMAX) AXIS ##_## MINMAX ##_PIN
-  #define _ENDSTOP_INVERTING(AXIS, MINMAX) AXIS ##_## MINMAX ##_ENDSTOP_INVERTING
-  #define _AXIS(AXIS) AXIS ##_AXIS
-  #define _ENDSTOP_HIT(AXIS) SBI(endstop_hit_bits, _ENDSTOP(AXIS, MIN))
-  #define _ENDSTOP(AXIS, MINMAX) AXIS ##_## MINMAX
-
-  // SET_ENDSTOP_BIT: set the current endstop bits for an endstop to its status
-  #define SET_ENDSTOP_BIT(AXIS, MINMAX) SET_BIT(current_endstop_bits, _ENDSTOP(AXIS, MINMAX), (READ(_ENDSTOP_PIN(AXIS, MINMAX)) != _ENDSTOP_INVERTING(AXIS, MINMAX)))
-  // COPY_BIT: copy the value of COPY_BIT to BIT in bits
-  #define COPY_BIT(bits, COPY_BIT, BIT) SET_BIT(bits, BIT, TEST(bits, COPY_BIT))
-  // TEST_ENDSTOP: test the old and the current status of an endstop
-  #define TEST_ENDSTOP(ENDSTOP) (TEST(current_endstop_bits, ENDSTOP) && TEST(old_endstop_bits, ENDSTOP))
-
-  #if ENABLED(COREXY) || ENABLED(COREXZ)
-
-    #define _SET_TRIGSTEPS(AXIS) do { \
-        float axis_pos = count_position[_AXIS(AXIS)]; \
-        if (_AXIS(AXIS) == A_AXIS) \
-          axis_pos = (axis_pos + count_position[CORE_AXIS_2]) / 2; \
-        else if (_AXIS(AXIS) == CORE_AXIS_2) \
-          axis_pos = (count_position[A_AXIS] - axis_pos) / 2; \
-        endstops_trigsteps[_AXIS(AXIS)] = axis_pos; \
-      } while(0)
-
-  #else
-
-    #define _SET_TRIGSTEPS(AXIS) endstops_trigsteps[_AXIS(AXIS)] = count_position[_AXIS(AXIS)]
-
-  #endif // COREXY || COREXZ
-
-  #define UPDATE_ENDSTOP(AXIS,MINMAX) do { \
-      SET_ENDSTOP_BIT(AXIS, MINMAX); \
-      if (TEST_ENDSTOP(_ENDSTOP(AXIS, MINMAX)) && current_block->steps[_AXIS(AXIS)] > 0) { \
-        _SET_TRIGSTEPS(AXIS); \
-        _ENDSTOP_HIT(AXIS); \
-        step_events_completed = current_block->step_event_count; \
-      } \
-    } while(0)
-
-  #if ENABLED(COREXY) || ENABLED(COREXZ)
-    // Head direction in -X axis for CoreXY and CoreXZ bots.
-    // If Delta1 == -Delta2, the movement is only in Y or Z axis
-    if ((current_block->steps[A_AXIS] != current_block->steps[CORE_AXIS_2]) || (TEST(out_bits, A_AXIS) == TEST(out_bits, CORE_AXIS_2))) {
-      if (TEST(out_bits, X_HEAD))
-  #else
-    if (TEST(out_bits, X_AXIS))   // stepping along -X axis (regular Cartesian bot)
-  #endif
-      { // -direction
-        #if ENABLED(DUAL_X_CARRIAGE)
-          // with 2 x-carriages, endstops are only checked in the homing direction for the active extruder
-          if ((current_block->active_extruder == 0 && X_HOME_DIR == -1) || (current_block->active_extruder != 0 && X2_HOME_DIR == -1))
-        #endif
-          {
-            #if HAS_X_MIN
-              UPDATE_ENDSTOP(X, MIN);
-            #endif
-          }
-      }
-      else { // +direction
-        #if ENABLED(DUAL_X_CARRIAGE)
-          // with 2 x-carriages, endstops are only checked in the homing direction for the active extruder
-          if ((current_block->active_extruder == 0 && X_HOME_DIR == 1) || (current_block->active_extruder != 0 && X2_HOME_DIR == 1))
-        #endif
-          {
-            #if HAS_X_MAX
-              UPDATE_ENDSTOP(X, MAX);
-            #endif
-          }
-      }
-  #if ENABLED(COREXY) || ENABLED(COREXZ)
-    }
-  #endif
-
-  #if ENABLED(COREXY)
-    // Head direction in -Y axis for CoreXY bots.
-    // If DeltaX == DeltaY, the movement is only in X axis
-    if ((current_block->steps[A_AXIS] != current_block->steps[B_AXIS]) || (TEST(out_bits, A_AXIS) != TEST(out_bits, B_AXIS))) {
-      if (TEST(out_bits, Y_HEAD))
-  #else
-      if (TEST(out_bits, Y_AXIS))   // -direction
-  #endif
-      { // -direction
-        #if HAS_Y_MIN
-          UPDATE_ENDSTOP(Y, MIN);
-        #endif
-      }
-      else { // +direction
-        #if HAS_Y_MAX
-          UPDATE_ENDSTOP(Y, MAX);
-        #endif
-      }
-  #if ENABLED(COREXY)
-    }
-  #endif
-
-  #if ENABLED(COREXZ)
-    // Head direction in -Z axis for CoreXZ bots.
-    // If DeltaX == DeltaZ, the movement is only in X axis
-    if ((current_block->steps[A_AXIS] != current_block->steps[C_AXIS]) || (TEST(out_bits, A_AXIS) != TEST(out_bits, C_AXIS))) {
-      if (TEST(out_bits, Z_HEAD))
-  #else
-      if (TEST(out_bits, Z_AXIS))
-  #endif
-      { // z -direction
-        #if HAS_Z_MIN
-
-          #if ENABLED(Z_DUAL_ENDSTOPS)
-            SET_ENDSTOP_BIT(Z, MIN);
-            #if HAS_Z2_MIN
-              SET_ENDSTOP_BIT(Z2, MIN);
-            #else
-              COPY_BIT(current_endstop_bits, Z_MIN, Z2_MIN);
-            #endif
-
-            byte z_test = TEST_ENDSTOP(Z_MIN) | (TEST_ENDSTOP(Z2_MIN) << 1); // bit 0 for Z, bit 1 for Z2
-
-            if (z_test && current_block->steps[Z_AXIS] > 0) { // z_test = Z_MIN || Z2_MIN
-              endstops_trigsteps[Z_AXIS] = count_position[Z_AXIS];
-              SBI(endstop_hit_bits, Z_MIN);
-              if (!performing_homing || (z_test == 0x3))  //if not performing home or if both endstops were trigged during homing...
-                step_events_completed = current_block->step_event_count;
-            }
-          #else // !Z_DUAL_ENDSTOPS
-
-            #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
-              if (z_probe_is_active) UPDATE_ENDSTOP(Z, MIN);
-            #else
-              UPDATE_ENDSTOP(Z, MIN);
-            #endif
-          #endif // !Z_DUAL_ENDSTOPS
-        #endif
-
-        #if ENABLED(Z_MIN_PROBE_ENDSTOP) && DISABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
-          if (z_probe_is_active) {
-            UPDATE_ENDSTOP(Z, MIN_PROBE);
-            if (TEST_ENDSTOP(Z_MIN_PROBE)) SBI(endstop_hit_bits, Z_MIN_PROBE);
-          }
-        #endif
-      }
-      else { // z +direction
-        #if HAS_Z_MAX
-
-          #if ENABLED(Z_DUAL_ENDSTOPS)
-
-            SET_ENDSTOP_BIT(Z, MAX);
-            #if HAS_Z2_MAX
-              SET_ENDSTOP_BIT(Z2, MAX);
-            #else
-              COPY_BIT(current_endstop_bits, Z_MAX, Z2_MAX);
-            #endif
-
-            byte z_test = TEST_ENDSTOP(Z_MAX) | (TEST_ENDSTOP(Z2_MAX) << 1); // bit 0 for Z, bit 1 for Z2
-
-            if (z_test && current_block->steps[Z_AXIS] > 0) {  // t_test = Z_MAX || Z2_MAX
-              endstops_trigsteps[Z_AXIS] = count_position[Z_AXIS];
-              SBI(endstop_hit_bits, Z_MIN);
-              if (!performing_homing || (z_test == 0x3))  //if not performing home or if both endstops were trigged during homing...
-                step_events_completed = current_block->step_event_count;
-            }
-
-          #else // !Z_DUAL_ENDSTOPS
-
-            UPDATE_ENDSTOP(Z, MAX);
-
-          #endif // !Z_DUAL_ENDSTOPS
-        #endif // Z_MAX_PIN
-      }
-  #if ENABLED(COREXZ)
-    }
-  #endif
-  old_endstop_bits = current_endstop_bits;
-}
-
-//         __________________________
-//        /|                        |\     _________________         ^
-//       / |                        | \   /|               |\        |
-//      /  |                        |  \ / |               | \       s
-//     /   |                        |   |  |               |  \      p
-//    /    |                        |   |  |               |   \     e
-//   +-----+------------------------+---+--+---------------+----+    e
-//   |               BLOCK 1            |      BLOCK 2          |    d
-//
-//                           time ----->
-//
-//  The trapezoid is the shape the speed curve over time. It starts at block->initial_rate, accelerates
-//  first block->accelerate_until step_events_completed, then keeps going at constant speed until
-//  step_events_completed reaches block->decelerate_after after which it decelerates until the trapezoid generator is reset.
-//  The slope of acceleration is calculated using v = u + at where t is the accumulated timer values of the steps so far.
-
-void st_wake_up() {
+/**
+ *         __________________________
+ *        /|                        |\     _________________         ^
+ *       / |                        | \   /|               |\        |
+ *      /  |                        |  \ / |               | \       s
+ *     /   |                        |   |  |               |  \      p
+ *    /    |                        |   |  |               |   \     e
+ *   +-----+------------------------+---+--+---------------+----+    e
+ *   |               BLOCK 1            |      BLOCK 2          |    d
+ *
+ *                           time ----->
+ *
+ *  The trapezoid is the shape the speed curve over time. It starts at block->initial_rate, accelerates
+ *  first block->accelerate_until step_events_completed, then keeps going at constant speed until
+ *  step_events_completed reaches block->decelerate_after after which it decelerates until the trapezoid generator is reset.
+ *  The slope of acceleration is calculated using v = u + at where t is the accumulated timer values of the steps so far.
+ */
+void Stepper::wake_up() {
   //  TCNT1 = 0;
   ENABLE_STEPPER_DRIVER_INTERRUPT();
 }
 
-FORCE_INLINE unsigned short calc_timer(unsigned short step_rate) {
-  unsigned short timer;
-
-  NOMORE(step_rate, MAX_STEP_FREQUENCY);
-
-  if (step_rate > 20000) { // If steprate > 20kHz >> step 4 times
-    step_rate = (step_rate >> 2) & 0x3fff;
-    step_loops = 4;
-  }
-  else if (step_rate > 10000) { // If steprate > 10kHz >> step 2 times
-    step_rate = (step_rate >> 1) & 0x7fff;
-    step_loops = 2;
-  }
-  else {
-    step_loops = 1;
-  }
-
-  NOLESS(step_rate, F_CPU / 500000);
-  step_rate -= F_CPU / 500000; // Correct for minimal speed
-  if (step_rate >= (8 * 256)) { // higher step rate
-    unsigned short table_address = (unsigned short)&speed_lookuptable_fast[(unsigned char)(step_rate >> 8)][0];
-    unsigned char tmp_step_rate = (step_rate & 0x00ff);
-    unsigned short gain = (unsigned short)pgm_read_word_near(table_address + 2);
-    MultiU16X8toH16(timer, tmp_step_rate, gain);
-    timer = (unsigned short)pgm_read_word_near(table_address) - timer;
-  }
-  else { // lower step rates
-    unsigned short table_address = (unsigned short)&speed_lookuptable_slow[0][0];
-    table_address += ((step_rate) >> 1) & 0xfffc;
-    timer = (unsigned short)pgm_read_word_near(table_address);
-    timer -= (((unsigned short)pgm_read_word_near(table_address + 2) * (unsigned char)(step_rate & 0x0007)) >> 3);
-  }
-  if (timer < 100) { timer = 100; MYSERIAL.print(MSG_STEPPER_TOO_HIGH); MYSERIAL.println(step_rate); }//(20kHz this should never happen)
-  return timer;
-}
-
 /**
  * Set the stepper direction of each axis
  *
  *   X_AXIS=A_AXIS and Y_AXIS=B_AXIS for COREXY
  *   X_AXIS=A_AXIS and Z_AXIS=C_AXIS for COREXZ
  */
-void set_stepper_direction() {
+void Stepper::set_directions() {
 
   #define SET_STEP_DIR(AXIS) \
-    if (TEST(out_bits, AXIS ##_AXIS)) { \
+    if (motor_direction(AXIS ##_AXIS)) { \
       AXIS ##_APPLY_DIR(INVERT_## AXIS ##_DIR, false); \
       count_direction[AXIS ##_AXIS] = -1; \
     } \
@@ -600,7 +224,7 @@ void set_stepper_direction() {
   SET_STEP_DIR(Z); // C
 
   #if DISABLED(ADVANCE)
-    if (TEST(out_bits, E_AXIS)) {
+    if (motor_direction(E_AXIS)) {
       REV_E_DIR();
       count_direction[E_AXIS] = -1;
     }
@@ -611,49 +235,11 @@ void set_stepper_direction() {
   #endif //!ADVANCE
 }
 
-// Initializes the trapezoid generator from the current block. Called whenever a new
-// block begins.
-FORCE_INLINE void trapezoid_generator_reset() {
-
-  static int8_t last_extruder = -1;
-
-  if (current_block->direction_bits != out_bits || current_block->active_extruder != last_extruder) {
-    out_bits = current_block->direction_bits;
-    last_extruder = current_block->active_extruder;
-    set_stepper_direction();
-  }
-
-  #if ENABLED(ADVANCE)
-    advance = current_block->initial_advance;
-    final_advance = current_block->final_advance;
-    // Do E steps + advance steps
-    e_steps[current_block->active_extruder] += ((advance >>8) - old_advance);
-    old_advance = advance >>8;
-  #endif
-  deceleration_time = 0;
-  // step_rate to timer interval
-  OCR1A_nominal = calc_timer(current_block->nominal_rate);
-  // make a note of the number of step loops required at nominal speed
-  step_loops_nominal = step_loops;
-  acc_step_rate = current_block->initial_rate;
-  acceleration_time = calc_timer(acc_step_rate);
-  OCR1A = acceleration_time;
-
-  // SERIAL_ECHO_START;
-  // SERIAL_ECHOPGM("advance :");
-  // SERIAL_ECHO(current_block->advance/256.0);
-  // SERIAL_ECHOPGM("advance rate :");
-  // SERIAL_ECHO(current_block->advance_rate/256.0);
-  // SERIAL_ECHOPGM("initial advance :");
-  // SERIAL_ECHO(current_block->initial_advance/256.0);
-  // SERIAL_ECHOPGM("final advance :");
-  // SERIAL_ECHOLN(current_block->final_advance/256.0);
-}
-
 // "The Stepper Driver Interrupt" - This timer interrupt is the workhorse.
 // It pops blocks from the block_buffer and executes them by pulsing the stepper pins appropriately.
-ISR(TIMER1_COMPA_vect) {
+ISR(TIMER1_COMPA_vect) { stepper.isr(); }
 
+void Stepper::isr() {
   if (cleaning_buffer_counter) {
     current_block = NULL;
     plan_discard_current_block();
@@ -672,8 +258,8 @@ ISR(TIMER1_COMPA_vect) {
     if (current_block) {
       current_block->busy = true;
       trapezoid_generator_reset();
-      counter_x = -(current_block->step_event_count >> 1);
-      counter_y = counter_z = counter_e = counter_x;
+      counter_X = -(current_block->step_event_count >> 1);
+      counter_Y = counter_Z = counter_E = counter_X;
       step_events_completed = 0;
 
       #if ENABLED(Z_LATE_ENABLE)
@@ -697,9 +283,9 @@ ISR(TIMER1_COMPA_vect) {
 
     // Update endstops state, if enabled
     #if ENABLED(HAS_Z_MIN_PROBE)
-      if (check_endstops || z_probe_is_active) update_endstops();
+      if (endstops.enabled || endstops.z_probe_enabled) endstops.update();
     #else
-      if (check_endstops) update_endstops();
+      if (endstops.enabled) endstops.update();
     #endif
 
     // Take multiple steps per interrupt (For high speed moves)
@@ -709,48 +295,47 @@ ISR(TIMER1_COMPA_vect) {
       #endif
 
       #if ENABLED(ADVANCE)
-        counter_e += current_block->steps[E_AXIS];
-        if (counter_e > 0) {
-          counter_e -= current_block->step_event_count;
-          e_steps[current_block->active_extruder] += TEST(out_bits, E_AXIS) ? -1 : 1;
+        counter_E += current_block->steps[E_AXIS];
+        if (counter_E > 0) {
+          counter_E -= current_block->step_event_count;
+          e_steps[current_block->active_extruder] += motor_direction(E_AXIS) ? -1 : 1;
         }
       #endif //ADVANCE
 
-      #define _COUNTER(axis) counter_## axis
+      #define _COUNTER(AXIS) counter_## AXIS
       #define _APPLY_STEP(AXIS) AXIS ##_APPLY_STEP
       #define _INVERT_STEP_PIN(AXIS) INVERT_## AXIS ##_STEP_PIN
 
-      #define STEP_ADD(axis, AXIS) \
-        _COUNTER(axis) += current_block->steps[_AXIS(AXIS)]; \
-        if (_COUNTER(axis) > 0) { _APPLY_STEP(AXIS)(!_INVERT_STEP_PIN(AXIS),0); }
+      #define STEP_ADD(AXIS) \
+        _COUNTER(AXIS) += current_block->steps[_AXIS(AXIS)]; \
+        if (_COUNTER(AXIS) > 0) { _APPLY_STEP(AXIS)(!_INVERT_STEP_PIN(AXIS),0); }
 
-      STEP_ADD(x,X);
-      STEP_ADD(y,Y);
-      STEP_ADD(z,Z);
+      STEP_ADD(X);
+      STEP_ADD(Y);
+      STEP_ADD(Z);
       #if DISABLED(ADVANCE)
-        STEP_ADD(e,E);
+        STEP_ADD(E);
       #endif
 
-      #define STEP_IF_COUNTER(axis, AXIS) \
-        if (_COUNTER(axis) > 0) { \
-          _COUNTER(axis) -= current_block->step_event_count; \
+      #define STEP_IF_COUNTER(AXIS) \
+        if (_COUNTER(AXIS) > 0) { \
+          _COUNTER(AXIS) -= current_block->step_event_count; \
           count_position[_AXIS(AXIS)] += count_direction[_AXIS(AXIS)]; \
           _APPLY_STEP(AXIS)(_INVERT_STEP_PIN(AXIS),0); \
         }
 
-      STEP_IF_COUNTER(x, X);
-      STEP_IF_COUNTER(y, Y);
-      STEP_IF_COUNTER(z, Z);
+      STEP_IF_COUNTER(X);
+      STEP_IF_COUNTER(Y);
+      STEP_IF_COUNTER(Z);
       #if DISABLED(ADVANCE)
-        STEP_IF_COUNTER(e, E);
+        STEP_IF_COUNTER(E);
       #endif
 
       step_events_completed++;
       if (step_events_completed >= current_block->step_event_count) break;
     }
     // Calculate new timer value
-    unsigned short timer;
-    unsigned short step_rate;
+    unsigned short timer, step_rate;
     if (step_events_completed <= (unsigned long)current_block->accelerate_until) {
 
       MultiU24X32toH16(acc_step_rate, acceleration_time, current_block->acceleration_rate);
@@ -817,10 +402,11 @@ ISR(TIMER1_COMPA_vect) {
 }
 
 #if ENABLED(ADVANCE)
-  unsigned char old_OCR0A;
   // Timer interrupt for E. e_steps is set in the main routine;
   // Timer 0 is shared with millies
-  ISR(TIMER0_COMPA_vect) {
+  ISR(TIMER0_COMPA_vect) { stepper.advance_isr(); }
+
+  void Stepper::advance_isr() {
     old_OCR0A += 52; // ~10kHz interrupt (250000 / 26 = 9615kHz)
     OCR0A = old_OCR0A;
 
@@ -852,9 +438,10 @@ ISR(TIMER1_COMPA_vect) {
       #endif
     }
   }
+
 #endif // ADVANCE
 
-void st_init() {
+void Stepper::init() {
   digipot_init(); //Initialize Digipot Motor Current
   microstep_init(); //Initialize Microstepping Pins
 
@@ -944,70 +531,10 @@ void st_init() {
     if (!E_ENABLE_ON) E3_ENABLE_WRITE(HIGH);
   #endif
 
-  //endstops and pullups
-
-  #if HAS_X_MIN
-    SET_INPUT(X_MIN_PIN);
-    #if ENABLED(ENDSTOPPULLUP_XMIN)
-      WRITE(X_MIN_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Y_MIN
-    SET_INPUT(Y_MIN_PIN);
-    #if ENABLED(ENDSTOPPULLUP_YMIN)
-      WRITE(Y_MIN_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Z_MIN
-    SET_INPUT(Z_MIN_PIN);
-    #if ENABLED(ENDSTOPPULLUP_ZMIN)
-      WRITE(Z_MIN_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Z2_MIN
-    SET_INPUT(Z2_MIN_PIN);
-    #if ENABLED(ENDSTOPPULLUP_ZMIN)
-      WRITE(Z2_MIN_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_X_MAX
-    SET_INPUT(X_MAX_PIN);
-    #if ENABLED(ENDSTOPPULLUP_XMAX)
-      WRITE(X_MAX_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Y_MAX
-    SET_INPUT(Y_MAX_PIN);
-    #if ENABLED(ENDSTOPPULLUP_YMAX)
-      WRITE(Y_MAX_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Z_MAX
-    SET_INPUT(Z_MAX_PIN);
-    #if ENABLED(ENDSTOPPULLUP_ZMAX)
-      WRITE(Z_MAX_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Z2_MAX
-    SET_INPUT(Z2_MAX_PIN);
-    #if ENABLED(ENDSTOPPULLUP_ZMAX)
-      WRITE(Z2_MAX_PIN,HIGH);
-    #endif
-  #endif
-
-  #if HAS_Z_PROBE && ENABLED(Z_MIN_PROBE_ENDSTOP) // Check for Z_MIN_PROBE_ENDSTOP so we don't pull a pin high unless it's to be used.
-    SET_INPUT(Z_MIN_PROBE_PIN);
-    #if ENABLED(ENDSTOPPULLUP_ZMIN_PROBE)
-      WRITE(Z_MIN_PROBE_PIN,HIGH);
-    #endif
-  #endif
+  //
+  // Init endstops and pullups here
+  //
+  endstops.init();
 
   #define _STEP_INIT(AXIS) AXIS ##_STEP_INIT
   #define _WRITE_STEP(AXIS, HIGHLOW) AXIS ##_STEP_WRITE(HIGHLOW)
@@ -1083,17 +610,17 @@ void st_init() {
     SBI(TIMSK0, OCIE0A);
   #endif //ADVANCE
 
-  enable_endstops(true); // Start with endstops active. After homing they can be disabled
+  endstops.enable(true); // Start with endstops active. After homing they can be disabled
   sei();
 
-  set_stepper_direction(); // Init directions to out_bits = 0
+  set_directions(); // Init directions to last_direction_bits = 0
 }
 
 
 /**
  * Block until all buffered steps are executed
  */
-void st_synchronize() { while (blocks_queued()) idle(); }
+void Stepper::synchronize() { while (blocks_queued()) idle(); }
 
 /**
  * Set the stepper positions directly in steps
@@ -1101,10 +628,10 @@ void st_synchronize() { while (blocks_queued()) idle(); }
  * The input is based on the typical per-axis XYZ steps.
  * For CORE machines XYZ needs to be translated to ABC.
  *
- * This allows st_get_axis_position_mm to correctly
+ * This allows get_axis_position_mm to correctly
  * derive the current XYZ position later on.
  */
-void st_set_position(const long& x, const long& y, const long& z, const long& e) {
+void Stepper::set_position(const long& x, const long& y, const long& z, const long& e) {
   CRITICAL_SECTION_START;
 
   #if ENABLED(COREXY)
@@ -1129,7 +656,7 @@ void st_set_position(const long& x, const long& y, const long& z, const long& e)
   CRITICAL_SECTION_END;
 }
 
-void st_set_e_position(const long& e) {
+void Stepper::set_e_position(const long& e) {
   CRITICAL_SECTION_START;
   count_position[E_AXIS] = e;
   CRITICAL_SECTION_END;
@@ -1138,7 +665,7 @@ void st_set_e_position(const long& e) {
 /**
  * Get a stepper's position in steps.
  */
-long st_get_position(AxisEnum axis) {
+long Stepper::position(AxisEnum axis) {
   CRITICAL_SECTION_START;
   long count_pos = count_position[axis];
   CRITICAL_SECTION_END;
@@ -1149,7 +676,7 @@ long st_get_position(AxisEnum axis) {
  * Get an axis position according to stepper position(s)
  * For CORE machines apply translation from ABC to XYZ.
  */
-float st_get_axis_position_mm(AxisEnum axis) {
+float Stepper::get_axis_position_mm(AxisEnum axis) {
   float axis_steps;
   #if ENABLED(COREXY) | ENABLED(COREXZ)
     if (axis == X_AXIS || axis == CORE_AXIS_2) {
@@ -1162,19 +689,19 @@ float st_get_axis_position_mm(AxisEnum axis) {
       axis_steps = (pos1 + ((axis == X_AXIS) ? pos2 : -pos2)) / 2.0f;
     }
     else
-      axis_steps = st_get_position(axis);
+      axis_steps = position(axis);
   #else
-    axis_steps = st_get_position(axis);
+    axis_steps = position(axis);
   #endif
   return axis_steps / axis_steps_per_unit[axis];
 }
 
-void finishAndDisableSteppers() {
-  st_synchronize();
+void Stepper::finish_and_disable() {
+  synchronize();
   disable_all_steppers();
 }
 
-void quickStop() {
+void Stepper::quick_stop() {
   cleaning_buffer_counter = 5000;
   DISABLE_STEPPER_DRIVER_INTERRUPT();
   while (blocks_queued()) plan_discard_current_block();
@@ -1182,11 +709,62 @@ void quickStop() {
   ENABLE_STEPPER_DRIVER_INTERRUPT();
 }
 
+void Stepper::endstop_triggered(AxisEnum axis) {
+
+  #if ENABLED(COREXY) || ENABLED(COREXZ)
+
+    float axis_pos = count_position[axis];
+    if (axis == A_AXIS)
+      axis_pos = (axis_pos + count_position[CORE_AXIS_2]) / 2;
+    else if (axis == CORE_AXIS_2)
+      axis_pos = (count_position[A_AXIS] - axis_pos) / 2;
+    endstops_trigsteps[axis] = axis_pos;
+
+  #else // !COREXY && !COREXZ
+
+    endstops_trigsteps[axis] = count_position[axis];
+
+  #endif // !COREXY && !COREXZ
+
+  kill_current_block();
+}
+
+void Stepper::report_positions() {
+  CRITICAL_SECTION_START;
+  long xpos = count_position[X_AXIS],
+       ypos = count_position[Y_AXIS],
+       zpos = count_position[Z_AXIS];
+  CRITICAL_SECTION_END;
+
+  #if ENABLED(COREXY) || ENABLED(COREXZ)
+    SERIAL_PROTOCOLPGM(MSG_COUNT_A);
+  #else
+    SERIAL_PROTOCOLPGM(MSG_COUNT_X);
+  #endif
+  SERIAL_PROTOCOL(xpos);
+
+  #if ENABLED(COREXY) || ENABLED(COREXZ)
+    SERIAL_PROTOCOLPGM(" B:");
+  #else
+    SERIAL_PROTOCOLPGM(" Y:");
+  #endif
+  SERIAL_PROTOCOL(ypos);
+
+  #if ENABLED(COREXZ) || ENABLED(COREXZ)
+    SERIAL_PROTOCOLPGM(" C:");
+  #else
+    SERIAL_PROTOCOLPGM(" Z:");
+  #endif
+  SERIAL_PROTOCOL(zpos);
+
+  SERIAL_EOL;
+}
+
 #if ENABLED(BABYSTEPPING)
 
   // MUST ONLY BE CALLED BY AN ISR,
   // No other ISR should ever interrupt this!
-  void babystep(const uint8_t axis, const bool direction) {
+  void Stepper::babystep(const uint8_t axis, const bool direction) {
 
     #define _ENABLE(axis) enable_## axis()
     #define _READ_DIR(AXIS) AXIS ##_DIR_READ
@@ -1256,10 +834,14 @@ void quickStop() {
 
 #endif //BABYSTEPPING
 
+/**
+ * Software-controlled Stepper Motor Current
+ */
+
 #if HAS_DIGIPOTSS
 
   // From Arduino DigitalPotControl example
-  void digitalPotWrite(int address, int value) {
+  void Stepper::digitalPotWrite(int address, int value) {
     digitalWrite(DIGIPOTSS_PIN, LOW); // take the SS pin low to select the chip
     SPI.transfer(address); //  send in the address and value via SPI:
     SPI.transfer(value);
@@ -1269,8 +851,7 @@ void quickStop() {
 
 #endif //HAS_DIGIPOTSS
 
-// Initialize Digipot Motor Current
-void digipot_init() {
+void Stepper::digipot_init() {
   #if HAS_DIGIPOTSS
     const uint8_t digipot_motor_current[] = DIGIPOT_MOTOR_CURRENT;
 
@@ -1299,7 +880,7 @@ void digipot_init() {
   #endif
 }
 
-void digipot_current(uint8_t driver, int current) {
+void Stepper::digipot_current(uint8_t driver, int current) {
   #if HAS_DIGIPOTSS
     const uint8_t digipot_ch[] = DIGIPOT_CHANNELS;
     digitalPotWrite(digipot_ch[driver], current);
@@ -1322,7 +903,7 @@ void digipot_current(uint8_t driver, int current) {
   #endif
 }
 
-void microstep_init() {
+void Stepper::microstep_init() {
   #if HAS_MICROSTEPS_E1
     pinMode(E1_MS1_PIN, OUTPUT);
     pinMode(E1_MS2_PIN, OUTPUT);
@@ -1343,7 +924,11 @@ void microstep_init() {
   #endif
 }
 
-void microstep_ms(uint8_t driver, int8_t ms1, int8_t ms2) {
+/**
+ * Software-controlled Microstepping
+ */
+
+void Stepper::microstep_ms(uint8_t driver, int8_t ms1, int8_t ms2) {
   if (ms1 >= 0) switch (driver) {
     case 0: digitalWrite(X_MS1_PIN, ms1); break;
     case 1: digitalWrite(Y_MS1_PIN, ms1); break;
@@ -1364,7 +949,7 @@ void microstep_ms(uint8_t driver, int8_t ms1, int8_t ms2) {
   }
 }
 
-void microstep_mode(uint8_t driver, uint8_t stepping_mode) {
+void Stepper::microstep_mode(uint8_t driver, uint8_t stepping_mode) {
   switch (stepping_mode) {
     case 1: microstep_ms(driver, MICROSTEP1); break;
     case 2: microstep_ms(driver, MICROSTEP2); break;
@@ -1374,7 +959,7 @@ void microstep_mode(uint8_t driver, uint8_t stepping_mode) {
   }
 }
 
-void microstep_readings() {
+void Stepper::microstep_readings() {
   SERIAL_PROTOCOLPGM("MS1,MS2 Pins\n");
   SERIAL_PROTOCOLPGM("X: ");
   SERIAL_PROTOCOL(digitalRead(X_MS1_PIN));
@@ -1396,7 +981,7 @@ void microstep_readings() {
 }
 
 #if ENABLED(Z_DUAL_ENDSTOPS)
-  void In_Homing_Process(bool state) { performing_homing = state; }
-  void Lock_z_motor(bool state) { locked_z_motor = state; }
-  void Lock_z2_motor(bool state) { locked_z2_motor = state; }
+  void Stepper::set_homing_flag(bool state) { performing_homing = state; }
+  void Stepper::set_z_lock(bool state) { locked_z_motor = state; }
+  void Stepper::set_z2_lock(bool state) { locked_z2_motor = state; }
 #endif
diff --git a/Marlin/stepper.h b/Marlin/stepper.h
index b0230b8cd2..3efad54694 100644
--- a/Marlin/stepper.h
+++ b/Marlin/stepper.h
@@ -21,90 +21,313 @@
  */
 
 /**
-  stepper.h - stepper motor driver: executes motion plans of planner.c using the stepper motors
-  Part of Grbl
+ * stepper.h - stepper motor driver: executes motion plans of planner.c using the stepper motors
+ * 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/>.
+ */
 
-  Copyright (c) 2009-2011 Simen Svale Skogsrud
+#ifndef STEPPER_H
+#define STEPPER_H
 
-  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.
+#include "planner.h"
+#include "speed_lookuptable.h"
+#include "stepper_indirection.h"
+#include "language.h"
 
-  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.
+class Stepper;
+extern Stepper stepper;
 
-  You should have received a copy of the GNU General Public License
-  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
-*/
+// intRes = intIn1 * intIn2 >> 16
+// uses:
+// r26 to store 0
+// r27 to store the byte 1 of the 24 bit result
+#define MultiU16X8toH16(intRes, charIn1, intIn2) \
+  asm volatile ( \
+                 "clr r26 \n\t" \
+                 "mul %A1, %B2 \n\t" \
+                 "movw %A0, r0 \n\t" \
+                 "mul %A1, %A2 \n\t" \
+                 "add %A0, r1 \n\t" \
+                 "adc %B0, r26 \n\t" \
+                 "lsr r0 \n\t" \
+                 "adc %A0, r26 \n\t" \
+                 "adc %B0, r26 \n\t" \
+                 "clr r1 \n\t" \
+                 : \
+                 "=&r" (intRes) \
+                 : \
+                 "d" (charIn1), \
+                 "d" (intIn2) \
+                 : \
+                 "r26" \
+               )
 
-#ifndef stepper_h
-#define stepper_h
+class Stepper {
 
-#include "planner.h"
-#include "stepper_indirection.h"
+  public:
+
+    block_t* current_block = NULL;  // A pointer to the block currently being traced
+
+    #if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
+      bool abort_on_endstop_hit = false;
+    #endif
+
+    #if ENABLED(Z_DUAL_ENDSTOPS)
+      bool performing_homing = false;
+    #endif
+
+    #if ENABLED(ADVANCE)
+      long e_steps[4];
+    #endif
+
+  private:
+
+    unsigned char last_direction_bits = 0;        // The next stepping-bits to be output
+    unsigned int cleaning_buffer_counter = 0;
+
+    #if ENABLED(Z_DUAL_ENDSTOPS)
+      bool locked_z_motor = false,
+           locked_z2_motor = false;
+    #endif
+
+    // Counter variables for the Bresenham line tracer
+    long counter_X = 0, counter_Y = 0, counter_Z = 0, counter_E = 0;
+    volatile unsigned long step_events_completed = 0; // The number of step events executed in the current block
+
+    #if ENABLED(ADVANCE)
+      unsigned char old_OCR0A;
+      long advance_rate, advance, final_advance = 0;
+      long old_advance = 0;
+    #endif
+
+    long acceleration_time, deceleration_time;
+    //unsigned long accelerate_until, decelerate_after, acceleration_rate, initial_rate, final_rate, nominal_rate;
+    unsigned short acc_step_rate; // needed for deceleration start point
+    uint8_t step_loops;
+    uint8_t step_loops_nominal;
+    unsigned short OCR1A_nominal;
+
+    volatile long endstops_trigsteps[3];
+    volatile long endstops_stepsTotal, endstops_stepsDone;
+
+    #if HAS_MOTOR_CURRENT_PWM
+      #ifndef PWM_MOTOR_CURRENT
+        #define PWM_MOTOR_CURRENT DEFAULT_PWM_MOTOR_CURRENT
+      #endif
+      const int motor_current_setting[3] = PWM_MOTOR_CURRENT;
+    #endif
+
+    //
+    // Positions of stepper motors, in step units
+    //
+    volatile long count_position[NUM_AXIS] = { 0 };
+
+    //
+    // Current direction of stepper motors (+1 or -1)
+    //
+    volatile signed char count_direction[NUM_AXIS] = { 1 };
+
+  public:
+
+    //
+    // Constructor / initializer
+    //
+    Stepper() {};
+
+    //
+    // Initialize stepper hardware
+    //
+    void init();
+
+    //
+    // Interrupt Service Routines
+    //
+
+    void isr();
+
+    #if ENABLED(ADVANCE)
+      void advance_isr();
+    #endif
+
+    //
+    // Block until all buffered steps are executed
+    //
+    void synchronize();
+
+    //
+    // Set the current position in steps
+    //
+    void set_position(const long& x, const long& y, const long& z, const long& e);
+    void set_e_position(const long& e);
+
+    //
+    // Set direction bits for all steppers
+    //
+    void set_directions();
+
+    //
+    // Get the position of a stepper, in steps
+    //
+    long position(AxisEnum axis);
+
+    //
+    // Report the positions of the steppers, in steps
+    //
+    void report_positions();
+
+    //
+    // Get the position (mm) of an axis based on stepper position(s)
+    //
+    float get_axis_position_mm(AxisEnum axis);
+
+    //
+    // The stepper subsystem goes to sleep when it runs out of things to execute. Call this
+    // to notify the subsystem that it is time to go to work.
+    //
+    void wake_up();
+
+    //
+    // Wait for moves to finish and disable all steppers
+    //
+    void finish_and_disable();
+
+    //
+    // Quickly stop all steppers and clear the blocks queue
+    //
+    void quick_stop();
 
-#if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
-  extern bool abort_on_endstop_hit;
-#endif
+    //
+    // The direction of a single motor
+    //
+    FORCE_INLINE bool motor_direction(AxisEnum axis) { return TEST(last_direction_bits, axis); }
 
-// Initialize and start the stepper motor subsystem
-void st_init();
+    #if HAS_DIGIPOTSS
+      void digitalPotWrite(int address, int value);
+    #endif
+    void microstep_ms(uint8_t driver, int8_t ms1, int8_t ms2);
+    void digipot_current(uint8_t driver, int current);
+    void microstep_readings();
 
-// Block until all buffered steps are executed
-void st_synchronize();
+    #if ENABLED(Z_DUAL_ENDSTOPS)
+      void set_homing_flag(bool state);
+      void set_z_lock(bool state);
+      void set_z2_lock(bool state);
+    #endif
 
-// Set current position in steps
-void st_set_position(const long& x, const long& y, const long& z, const long& e);
-void st_set_e_position(const long& e);
+    #if ENABLED(BABYSTEPPING)
+      void babystep(const uint8_t axis, const bool direction); // perform a short step with a single stepper motor, outside of any convention
+    #endif
 
-// Get current position in steps
-long st_get_position(AxisEnum axis);
+    inline void kill_current_block() {
+      step_events_completed = current_block->step_event_count;
+    }
 
-// Get current axis position in mm
-float st_get_axis_position_mm(AxisEnum axis);
+    //
+    // Handle a triggered endstop
+    //
+    void endstop_triggered(AxisEnum axis);
 
-// The stepper subsystem goes to sleep when it runs out of things to execute. Call this
-// to notify the subsystem that it is time to go to work.
-void st_wake_up();
+    //
+    // Triggered position of an axis in mm (not core-savvy)
+    //
+    FORCE_INLINE float triggered_position_mm(AxisEnum axis) {
+      return endstops_trigsteps[axis] / axis_steps_per_unit[axis];
+    }
 
+    FORCE_INLINE unsigned short calc_timer(unsigned short step_rate) {
+      unsigned short timer;
 
-void checkHitEndstops(); //call from somewhere to create an serial error message with the locations the endstops where hit, in case they were triggered
-void endstops_hit_on_purpose(); //avoid creation of the message, i.e. after homing and before a routine call of checkHitEndstops();
+      NOMORE(step_rate, MAX_STEP_FREQUENCY);
 
-void enable_endstops(bool check); // Enable/disable endstop checking
+      if (step_rate > 20000) { // If steprate > 20kHz >> step 4 times
+        step_rate = (step_rate >> 2) & 0x3fff;
+        step_loops = 4;
+      }
+      else if (step_rate > 10000) { // If steprate > 10kHz >> step 2 times
+        step_rate = (step_rate >> 1) & 0x7fff;
+        step_loops = 2;
+      }
+      else {
+        step_loops = 1;
+      }
 
-void enable_endstops_globally(bool check);
-void endstops_not_homing();
+      NOLESS(step_rate, F_CPU / 500000);
+      step_rate -= F_CPU / 500000; // Correct for minimal speed
+      if (step_rate >= (8 * 256)) { // higher step rate
+        unsigned short table_address = (unsigned short)&speed_lookuptable_fast[(unsigned char)(step_rate >> 8)][0];
+        unsigned char tmp_step_rate = (step_rate & 0x00ff);
+        unsigned short gain = (unsigned short)pgm_read_word_near(table_address + 2);
+        MultiU16X8toH16(timer, tmp_step_rate, gain);
+        timer = (unsigned short)pgm_read_word_near(table_address) - timer;
+      }
+      else { // lower step rates
+        unsigned short table_address = (unsigned short)&speed_lookuptable_slow[0][0];
+        table_address += ((step_rate) >> 1) & 0xfffc;
+        timer = (unsigned short)pgm_read_word_near(table_address);
+        timer -= (((unsigned short)pgm_read_word_near(table_address + 2) * (unsigned char)(step_rate & 0x0007)) >> 3);
+      }
+      if (timer < 100) { timer = 100; MYSERIAL.print(MSG_STEPPER_TOO_HIGH); MYSERIAL.println(step_rate); }//(20kHz this should never happen)
+      return timer;
+    }
 
-void checkStepperErrors(); //Print errors detected by the stepper
+    // Initializes the trapezoid generator from the current block. Called whenever a new
+    // block begins.
+    FORCE_INLINE void trapezoid_generator_reset() {
 
-void finishAndDisableSteppers();
+      static int8_t last_extruder = -1;
 
-extern block_t* current_block;  // A pointer to the block currently being traced
+      if (current_block->direction_bits != last_direction_bits || current_block->active_extruder != last_extruder) {
+        last_direction_bits = current_block->direction_bits;
+        last_extruder = current_block->active_extruder;
+        set_directions();
+      }
 
-void quickStop();
+      #if ENABLED(ADVANCE)
+        advance = current_block->initial_advance;
+        final_advance = current_block->final_advance;
+        // Do E steps + advance steps
+        e_steps[current_block->active_extruder] += ((advance >>8) - old_advance);
+        old_advance = advance >>8;
+      #endif
+      deceleration_time = 0;
+      // step_rate to timer interval
+      OCR1A_nominal = calc_timer(current_block->nominal_rate);
+      // make a note of the number of step loops required at nominal speed
+      step_loops_nominal = step_loops;
+      acc_step_rate = current_block->initial_rate;
+      acceleration_time = calc_timer(acc_step_rate);
+      OCR1A = acceleration_time;
 
-#if HAS_DIGIPOTSS
-  void digitalPotWrite(int address, int value);
-#endif
-void microstep_ms(uint8_t driver, int8_t ms1, int8_t ms2);
-void microstep_mode(uint8_t driver, uint8_t stepping);
-void digipot_init();
-void digipot_current(uint8_t driver, int current);
-void microstep_init();
-void microstep_readings();
+      // SERIAL_ECHO_START;
+      // SERIAL_ECHOPGM("advance :");
+      // SERIAL_ECHO(current_block->advance/256.0);
+      // SERIAL_ECHOPGM("advance rate :");
+      // SERIAL_ECHO(current_block->advance_rate/256.0);
+      // SERIAL_ECHOPGM("initial advance :");
+      // SERIAL_ECHO(current_block->initial_advance/256.0);
+      // SERIAL_ECHOPGM("final advance :");
+      // SERIAL_ECHOLN(current_block->final_advance/256.0);
+    }
 
-#if ENABLED(Z_DUAL_ENDSTOPS)
-  void In_Homing_Process(bool state);
-  void Lock_z_motor(bool state);
-  void Lock_z2_motor(bool state);
-#endif
+  private:
+    void microstep_mode(uint8_t driver, uint8_t stepping);
+    void digipot_init();
+    void microstep_init();
 
-#if ENABLED(BABYSTEPPING)
-  void babystep(const uint8_t axis, const bool direction); // perform a short step with a single stepper motor, outside of any convention
-#endif
+};
 
-#endif
+#endif // STEPPER_H
\ No newline at end of file
diff --git a/Marlin/temperature.cpp b/Marlin/temperature.cpp
index 5713cb6937..de61e63304 100644
--- a/Marlin/temperature.cpp
+++ b/Marlin/temperature.cpp
@@ -604,7 +604,7 @@ float get_pid_output(int e) {
         #if ENABLED(PID_ADD_EXTRUSION_RATE)
           cTerm[e] = 0;
           if (e == active_extruder) {
-            long e_position = st_get_position(E_AXIS);
+            long e_position = stepper.position(E_AXIS);
             if (e_position > last_position[e]) {
               lpq[lpq_ptr++] = e_position - last_position[e];
               last_position[e] = e_position;
diff --git a/Marlin/ultralcd.cpp b/Marlin/ultralcd.cpp
index 97a07f5232..33ede883a0 100644
--- a/Marlin/ultralcd.cpp
+++ b/Marlin/ultralcd.cpp
@@ -476,7 +476,7 @@ inline void line_to_current(AxisEnum axis) {
   static void lcd_sdcard_resume() { card.startFileprint(); }
 
   static void lcd_sdcard_stop() {
-    quickStop();
+    stepper.quick_stop();
     card.sdprinting = false;
     card.closefile();
     autotempShutdown();
@@ -911,7 +911,7 @@ void lcd_cooldown() {
       current_position[Z_AXIS] = MESH_HOME_SEARCH_Z;
       line_to_current(Z_AXIS);
     #endif
-    st_synchronize();
+    stepper.synchronize();
   }
 
   static void _lcd_level_goto_next_point();
@@ -964,7 +964,7 @@ void lcd_cooldown() {
             #endif
           ;
           line_to_current(Z_AXIS);
-          st_synchronize();
+          stepper.synchronize();
 
           mbl.active = true;
           enqueue_and_echo_commands_P(PSTR("G28"));