Pulldown pin mode support (#9701)

Implemented for LPC1768.

Marlin/src/config/examples/Malyan/M150/Configuration.h

@@ -508,11 +508,10 @@
 //#define USE_YMAX_PLUG
 //#define USE_ZMAX_PLUG
 
-// coarse Endstop Settings
-#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors
-
+// Enable pullup for all endstops to prevent a floating state
+#define ENDSTOPPULLUPS
 #if DISABLED(ENDSTOPPULLUPS)
-  // fine endstop settings: Individual pullups. will be ignored if ENDSTOPPULLUPS is defined
+  // Disable ENDSTOPPULLUPS to set pullups individually
   //#define ENDSTOPPULLUP_XMAX
   //#define ENDSTOPPULLUP_YMAX
   //#define ENDSTOPPULLUP_ZMAX
@@ -522,6 +521,19 @@
   //#define ENDSTOPPULLUP_ZMIN_PROBE
 #endif
 
+// Enable pulldown for all endstops to prevent a floating state
+//#define ENDSTOPPULLDOWNS
+#if DISABLED(ENDSTOPPULLDOWNS)
+  // Disable ENDSTOPPULLDOWNS to set pulldowns individually
+  //#define ENDSTOPPULLDOWN_XMAX
+  //#define ENDSTOPPULLDOWN_YMAX
+  //#define ENDSTOPPULLDOWN_ZMAX
+  //#define ENDSTOPPULLDOWN_XMIN
+  //#define ENDSTOPPULLDOWN_YMIN
+  //#define ENDSTOPPULLDOWN_ZMIN
+  //#define ENDSTOPPULLDOWN_ZMIN_PROBE
+#endif
+
 // Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
 
 #define X_MIN_ENDSTOP_INVERTING true // set to true to invert the logic of the endstop.
@@ -874,7 +886,8 @@
 //#define FILAMENT_RUNOUT_SENSOR
 #if ENABLED(FILAMENT_RUNOUT_SENSOR)
   #define FIL_RUNOUT_INVERTING false // set to true to invert the logic of the sensor.
-  #define ENDSTOPPULLUP_FIL_RUNOUT // Uncomment to use internal pullup for filament runout pins if the sensor is defined.
+  #define FIL_RUNOUT_PULLUP          // Use internal pullup for filament runout pins.
+  //#define FIL_RUNOUT_PULLDOWN      // Use internal pulldown for filament runout pins.
   #define FILAMENT_RUNOUT_SCRIPT "M600"
 #endif