Fix CALIBRATION_GCODE pin handling

Marlin/Configuration_adv.h

@@ -840,8 +840,8 @@
 
   // Define the pin to read during calibration
   #ifndef CALIBRATION_PIN
-    #define CALIBRATION_PIN -1 // Override in pins.h or set to -1 to use your Z endstop
-    #define CALIBRATION_PIN_INVERTING false // Set to true to invert the pin
+    //#define CALIBRATION_PIN -1            // Define here to override the default pin
+    #define CALIBRATION_PIN_INVERTING false // Set to true to invert the custom pin
     //#define CALIBRATION_PIN_PULLDOWN
     #define CALIBRATION_PIN_PULLUP
   #endif

Marlin/src/HAL/HAL_DUE/EepromEmulation.cpp

@@ -1,3 +1,24 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 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/>.
+ *
+ */
 
 /* EEPROM emulation over flash with reduced wear
  *

Marlin/src/gcode/calibrate/G425.cpp

@@ -128,13 +128,15 @@ inline void park_above_object(measurements_t &m, const float uncertainty) {
 #endif
 
 inline bool read_calibration_pin() {
-  #if HAS_CALIBRATION_PIN
-    return (READ(CALIBRATION_PIN) != CALIBRATION_PIN_INVERTING);
-  #elif ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)
-    return (READ(Z_MIN_PIN) != Z_MIN_ENDSTOP_INVERTING);
+  return (
+    #if PIN_EXISTS(CALIBRATION)
+      READ(CALIBRATION_PIN) != CALIBRATION_PIN_INVERTING
+    #elif HAS_CUSTOM_PROBE_PIN
+      READ(Z_MIN_PROBE_PIN) != Z_MIN_PROBE_ENDSTOP_INVERTING
     #else
-    return (READ(Z_MIN_PROBE_PIN) != Z_MIN_PROBE_ENDSTOP_INVERTING);
+      READ(Z_MIN_PIN) != Z_MIN_ENDSTOP_INVERTING
     #endif
+  );
 }
 
 /**

Marlin/src/inc/Conditionals_post.h

@@ -1443,7 +1443,6 @@
 #define HAS_Z4_MIN (PIN_EXISTS(Z4_MIN))
 #define HAS_Z4_MAX (PIN_EXISTS(Z4_MAX))
 #define HAS_Z_MIN_PROBE_PIN (HAS_CUSTOM_PROBE_PIN && PIN_EXISTS(Z_MIN_PROBE))
-#define HAS_CALIBRATION_PIN (PIN_EXISTS(CALIBRATION))
 
 //
 // ADC Temp Sensors (Thermistor or Thermocouple with amplifier ADC interface)

Marlin/src/module/endstops.cpp

@@ -256,7 +256,7 @@ void Endstops::init() {
     #endif
   #endif
 
-  #if HAS_CALIBRATION_PIN
+  #if PIN_EXISTS(CALIBRATION)
     #if ENABLED(CALIBRATION_PIN_PULLUP)
       SET_INPUT_PULLUP(CALIBRATION_PIN);
     #elif ENABLED(CALIBRATION_PIN_PULLDOWN)

Marlin/src/pins/sam/pins_CNCONTROLS_15D.h

@@ -1,3 +1,25 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 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/>.
+ *
+ */
+
 /**
  * CNControls V15 for HMS434 with DUE pin assignments
  */
@@ -92,6 +114,10 @@
 //#define PWM_2_PIN          13
 //#define SPARE_IO           17
 #define BEEPER_PIN         13
-#define CALIBRATION_PIN    66
 #define STAT_LED_BLUE_PIN  -1
 #define STAT_LED_RED_PIN   31
+
+// G425 CALIBRATION_GCODE default pin
+#ifndef CALIBRATION_PIN
+  #define CALIBRATION_PIN  66
+#endif