diff --git a/Marlin/src/Marlin.cpp b/Marlin/src/Marlin.cpp
index b1654cd23b..38e5302ea8 100644
--- a/Marlin/src/Marlin.cpp
+++ b/Marlin/src/Marlin.cpp
@@ -719,6 +719,10 @@ void setup() {
     tmc2208_serial_begin();
   #endif
 
+  #ifdef BOARD_INIT
+    BOARD_INIT();
+  #endif
+
   // Check startup - does nothing if bootloader sets MCUSR to 0
   byte mcu = HAL_get_reset_source();
   if (mcu &  1) SERIAL_ECHOLNPGM(MSG_POWERUP);
diff --git a/Marlin/src/pins/pins_RADDS.h b/Marlin/src/pins/pins_RADDS.h
index 68132604c7..872423d68d 100644
--- a/Marlin/src/pins/pins_RADDS.h
+++ b/Marlin/src/pins/pins_RADDS.h
@@ -100,29 +100,39 @@
   #define E2_CS_PIN        35
 #endif
 
-// For Extension Board V2
+//
+// Extension Board V2
 // http://doku.radds.org/dokumentation/extension-board
-//#define E3_STEP_PIN        35
-//#define E3_DIR_PIN         33
-//#define E3_ENABLE_PIN      37
-//#ifndef E3_CS_PIN
-//  #define E3_CS_PIN         6
-//#endif
+//
+//#define RADDS_EXTENSION
+#if ENABLED(RADDS_EXTENSION)
+  #define E3_STEP_PIN        35
+  #define E3_DIR_PIN         33
+  #define E3_ENABLE_PIN      37
+  #ifndef E3_CS_PIN
+    #define E3_CS_PIN         6
+  #endif
 
-//#define Z2_STEP_PIN        29
-//#define Z2_DIR_PIN         27
-//#define Z2_ENABLE_PIN      31
-//#ifndef Z2_CS_PIN
-//  #define Z2_CS_PIN        39
-//#endif
+  #define E3_MS1_PIN         67
+  #define E3_MS2_PIN         68
+  #define E3_MS3_PIN         69
 
-// Microstepping pins - Mapping not from fastio.h (?)
-//#define E3_MS1_PIN         67
-//#define E3_MS2_PIN         68
-//#define E3_MS3_PIN         69
-//#define Z2_MS1_PIN         67   // shared with E3_MS1_PIN
-//#define Z2_MS2_PIN         68   // shared with E3_MS2_PIN
-//#define Z2_MS3_PIN         69   // shared with E3_MS3_PIN
+  #define Z2_STEP_PIN        29
+  #define Z2_DIR_PIN         27
+  #define Z2_ENABLE_PIN      31
+  #ifndef Z2_CS_PIN
+    #define Z2_CS_PIN        39
+  #endif
+
+  #define Z2_MS1_PIN         67   // shared with E3_MS1_PIN
+  #define Z2_MS2_PIN         68   // shared with E3_MS2_PIN
+  #define Z2_MS3_PIN         69   // shared with E3_MS3_PIN
+
+  #define RADDS_EXT_VDD1_PIN 25
+  #define RADDS_EXT_VDD2_PIN 66
+
+  #define BOARD_INIT() OUT_WRITE(RADDS_EXT_VDD1_PIN, HIGH); OUT_WRITE(RADDS_EXT_VDD2_PIN, HIGH)
+#endif
 
 //
 // Temperature Sensors