diff --git a/optimized_user_settings.cfg b/optimized_user_settings.cfg
index 5496f3f..460bba3 100644
--- a/optimized_user_settings.cfg
+++ b/optimized_user_settings.cfg
@@ -42,19 +42,30 @@ min_temp: 5
 max_temp: 105
 
 # ============================================================================
-# ADXL345 ACCELEROMETER (integrated in Cartographer probe)
+# ADXL345 ACCELEROMETER
 # ============================================================================
-# IMPORTANT: Select the correct cs_pin for your Cartographer version!
+# Option 1: Cartographer integrated (V3 or V4)
 # - Cartographer V3: cs_pin: cartographer:PA3
 # - Cartographer V4: cs_pin: cartographer:PA0
-# Using the wrong pin causes: "Invalid adxl345 id (got 0 vs e5)"
+#
+# Option 2: Neptune 4 Plus mainboard (fallback if Cartographer ADXL fails)
+# - cs_pin: PG11 (Neptune 4 Plus built-in ADXL)
+# - spi_bus: spi2
 # ============================================================================
 
+# Neptune 4 Plus built-in ADXL345 (use this if Cartographer ADXL fails)
 [adxl345]
-cs_pin: cartographer:PA3    # ← CHANGE TO cartographer:PA0 FOR V4!
-spi_bus: spi1
+cs_pin: PG11
+spi_bus: spi2
 axes_map: x, y, z
 
+# Cartographer ADXL (alternative - comment out above, uncomment below)
+#[adxl345]
+#cs_pin: cartographer:PA3    # V3
+#cs_pin: cartographer:PA0    # V4
+#spi_bus: spi1
+#axes_map: x, y, z
+
 [resonance_tester]
 accel_chip: adxl345
 probe_points: 165, 165, 20
diff --git a/user_settings_clean.cfg b/user_settings_clean.cfg
index af3c4d9..6ce43f3 100644
--- a/user_settings_clean.cfg
+++ b/user_settings_clean.cfg
@@ -42,19 +42,30 @@ min_temp: 5
 max_temp: 105
 
 # ============================================================================
-# ADXL345 ACCELEROMETER (integrated in Cartographer probe)
+# ADXL345 ACCELEROMETER
 # ============================================================================
-# IMPORTANT: Select the correct cs_pin for your Cartographer version!
+# Option 1: Cartographer integrated (V3 or V4)
 # - Cartographer V3: cs_pin: cartographer:PA3
 # - Cartographer V4: cs_pin: cartographer:PA0
-# Using the wrong pin causes: "Invalid adxl345 id (got 0 vs e5)"
+#
+# Option 2: Neptune 4 Plus mainboard (fallback if Cartographer ADXL fails)
+# - cs_pin: PG11 (Neptune 4 Plus built-in ADXL)
+# - spi_bus: spi2
 # ============================================================================
 
+# Neptune 4 Plus built-in ADXL345 (use this if Cartographer ADXL fails)
 [adxl345]
-cs_pin: cartographer:PA3    # ← CHANGE TO cartographer:PA0 FOR V4!
-spi_bus: spi1
+cs_pin: PG11
+spi_bus: spi2
 axes_map: x, y, z
 
+# Cartographer ADXL (alternative - comment out above, uncomment below)
+#[adxl345]
+#cs_pin: cartographer:PA3    # V3
+#cs_pin: cartographer:PA0    # V4
+#spi_bus: spi1
+#axes_map: x, y, z
+
 [resonance_tester]
 accel_chip: adxl345
 probe_points: 165, 165, 20