🔧 Improve SD_DETECT_STATE default (#21885)

Marlin/src/inc/Conditionals_post.h

@@ -330,11 +330,6 @@
  */
 #if ENABLED(SDSUPPORT)
 
-  // Extender cable doesn't support SD_DETECT_PIN
-  #if ENABLED(NO_SD_DETECT)
-    #undef SD_DETECT_PIN
-  #endif
-
   #if HAS_SD_HOST_DRIVE && SD_CONNECTION_IS(ONBOARD)
     //
     // The external SD card is not used. Hardware SPI is used to access the card.
@@ -345,18 +340,20 @@
     #define HAS_SHARED_MEDIA 1
   #endif
 
-  #if PIN_EXISTS(SD_DETECT)
-    #if HAS_LCD_MENU && (SD_CONNECTION_IS(LCD) || !defined(SDCARD_CONNECTION))
-      #undef SD_DETECT_STATE
-      #if ENABLED(ELB_FULL_GRAPHIC_CONTROLLER)
-        #define SD_DETECT_STATE HIGH
-      #endif
-    #endif
-    #ifndef SD_DETECT_STATE
+  // Set SD_DETECT_STATE based on hardware if not overridden
+  #if PIN_EXISTS(SD_DETECT) && !defined(SD_DETECT_STATE)
+    #if BOTH(HAS_LCD_MENU, ELB_FULL_GRAPHIC_CONTROLLER) && (SD_CONNECTION_IS(LCD) || !defined(SDCARD_CONNECTION))
+      #define SD_DETECT_STATE HIGH
+    #else
       #define SD_DETECT_STATE LOW
     #endif
   #endif
 
+  // Extender cable doesn't support SD_DETECT_PIN
+  #if ENABLED(NO_SD_DETECT)
+    #undef SD_DETECT_PIN
+  #endif
+
   #if DISABLED(USB_FLASH_DRIVE_SUPPORT) || BOTH(MULTI_VOLUME, VOLUME_SD_ONBOARD)
     #if ENABLED(SDIO_SUPPORT)
       #define NEED_SD2CARD_SDIO 1

Marlin/src/inc/SanityCheck.h

@@ -761,6 +761,13 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
 #endif
 
 /**
+ * SD Card Settings
+ */
+#if ALL(SDSUPPORT, ELB_FULL_GRAPHIC_CONTROLLER, HAS_LCD_MENU) && PIN_EXISTS(SD_DETECT) && SD_DETECT_STATE != HIGH && (SD_CONNECTION_IS(LCD) || !defined(SDCARD_CONNECTION))
+  #error "SD_DETECT_STATE must be set HIGH for SD on the ELB_FULL_GRAPHIC_CONTROLLER."
+#endif
+
+/**
  * SD File Sorting
  */
 #if ENABLED(SDCARD_SORT_ALPHA)

Marlin/src/pins/stm32f4/pins_BTT_OCTOPUS_V1_0.h

@@ -349,8 +349,11 @@
 //
 #if SD_CONNECTION_IS(ONBOARD)
   #define SDIO_SUPPORT                            // Use SDIO for onboard SD
-  #undef SD_DETECT_STATE
-  #define SD_DETECT_STATE                   HIGH
+  #ifndef SD_DETECT_STATE
+    #define SD_DETECT_STATE HIGH
+  #elif SD_DETECT_STATE == LOW
+    #error "BOARD_BTT_OCTOPUS_V1_0 onboard SD requires SD_DETECT_STATE set to HIGH."
+  #endif
   #define SD_DETECT_PIN                     PC14
 #elif SD_CONNECTION_IS(LCD)