From 98bc595c3317aaef028ed5c4900b112fc2008845 Mon Sep 17 00:00:00 2001
From: djessup <djessup@users.noreply.github.com>
Date: Sat, 18 Apr 2020 00:02:21 +1000
Subject: [PATCH] Add USE_PROBE_FOR_Z_HOMING option (#17359)

---
 Marlin/Configuration.h            | 10 ++++++----
 Marlin/src/inc/Conditionals_LCD.h |  2 +-
 Marlin/src/inc/SanityCheck.h      | 12 +++++++++---
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/Marlin/Configuration.h b/Marlin/Configuration.h
index 09942ace0e6a6..0b3d580530146 100644
--- a/Marlin/Configuration.h
+++ b/Marlin/Configuration.h
@@ -824,12 +824,15 @@
 //
 
 /**
- * Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
- *
- * Enable this option for a probe connected to the Z Min endstop pin.
+ * Enable this option for a probe connected to the Z-MIN pin.
+ * The probe replaces the Z-MIN endstop and is used for Z homing.
+ * (Automatically enables USE_PROBE_FOR_Z_HOMING.)
  */
 #define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
 
+// Force the use of the probe for Z-axis homing
+//#define USE_PROBE_FOR_Z_HOMING
+
 /**
  * Z_MIN_PROBE_PIN
  *
@@ -1335,7 +1338,6 @@
  */
 //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10"
 
-
 // @section homing
 
 // The center of the bed is at (X=0, Y=0)
diff --git a/Marlin/src/inc/Conditionals_LCD.h b/Marlin/src/inc/Conditionals_LCD.h
index dd1f13fae0f88..7adb08a4e6780 100644
--- a/Marlin/src/inc/Conditionals_LCD.h
+++ b/Marlin/src/inc/Conditionals_LCD.h
@@ -583,7 +583,7 @@
   #if DISABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)
     #define HAS_CUSTOM_PROBE_PIN 1
   #endif
-  #if Z_HOME_DIR < 0 && !HAS_CUSTOM_PROBE_PIN
+  #if Z_HOME_DIR < 0 && (!HAS_CUSTOM_PROBE_PIN || ENABLED(USE_PROBE_FOR_Z_HOMING))
     #define HOMING_Z_WITH_PROBE 1
   #endif
   #ifndef Z_PROBE_LOW_POINT
diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index ab64c9a4f89f1..bcfeecc9f8b38 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -1815,8 +1815,10 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
  * Endstop Tests
  */
 
-#define _PLUG_UNUSED_TEST(AXIS,PLUG) (DISABLED(USE_##PLUG##MIN_PLUG, USE_##PLUG##MAX_PLUG) && !(ENABLED(AXIS##_DUAL_ENDSTOPS) && WITHIN(AXIS##2_USE_ENDSTOP, _##PLUG##MAX_, _##PLUG##MIN_)))
-#define _AXIS_PLUG_UNUSED_TEST(AXIS) (_PLUG_UNUSED_TEST(AXIS,X) && _PLUG_UNUSED_TEST(AXIS,Y) && _PLUG_UNUSED_TEST(AXIS,Z))
+#define _PLUG_UNUSED_TEST(A,P) (DISABLED(USE_##P##MIN_PLUG, USE_##P##MAX_PLUG) \
+  && !(ENABLED(A##_DUAL_ENDSTOPS) && WITHIN(A##2_USE_ENDSTOP, _##P##MAX_, _##P##MIN_)) \
+  && !(ENABLED(A##_MULTI_ENDSTOPS) && WITHIN(A##2_USE_ENDSTOP, _##P##MAX_, _##P##MIN_)) )
+#define _AXIS_PLUG_UNUSED_TEST(A) (_PLUG_UNUSED_TEST(A,X) && _PLUG_UNUSED_TEST(A,Y) && _PLUG_UNUSED_TEST(A,Z))
 
 // At least 3 endstop plugs must be used
 #if _AXIS_PLUG_UNUSED_TEST(X)
@@ -1841,8 +1843,12 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
     #error "Enable USE_YMAX_PLUG when homing Y to MAX."
   #endif
 #endif
-#if Z_HOME_DIR < 0 && DISABLED(USE_ZMIN_PLUG)
+
+// Z homing direction and plug usage flags
+#if Z_HOME_DIR < 0 && NONE(USE_ZMIN_PLUG, HOMING_Z_WITH_PROBE)
   #error "Enable USE_ZMIN_PLUG when homing Z to MIN."
+#elif Z_HOME_DIR > 0 && ENABLED(USE_PROBE_FOR_Z_HOMING)
+  #error "Z_HOME_DIR must be -1 when homing Z with the probe."
 #elif Z_HOME_DIR > 0 && DISABLED(USE_ZMAX_PLUG)
   #error "Enable USE_ZMAX_PLUG when homing Z to MAX."
 #endif