Index: ../firmware/target/arm/usb-fw-pp502x.c
===================================================================
--- ../firmware/target/arm/usb-fw-pp502x.c	(revision 15973)
+++ ../firmware/target/arm/usb-fw-pp502x.c	(working copy)
@@ -33,18 +33,23 @@
 void usb_init_device(void)
 {
     /* enable usb module */
-    GPO32_ENABLE |= 0x200;  
+//AB    GPO32_ENABLE |= 0x200;  //not needed by testing on ipod 5G?
 
     outl(inl(0x7000002C) | 0x3000000, 0x7000002C);  
     DEV_EN |= DEV_USB;
+    DEV_EN |= 0x8;
 
     DEV_RS |= DEV_USB; /* reset usb start */  
-    DEV_RS &=~DEV_USB;/* reset usb end */  
+    DEV_RS &=~DEV_USB; /* reset usb end */  
 
-    DEV_INIT2 |= INIT_USB;
+//AB    DEV_INIT2 |= INIT_USB;  //not needed by testing on ipod 5G?
     while ((inl(0x70000028) & 0x80) == 0);
     outl(inl(0x70000028) | 0x2, 0x70000028);
     udelay(0x186A0);
+    
+    /* disable USB-device until USB is detected via GPIO */
+    DEV_EN &= ~DEV_USB;
+    DEV_EN &= ~0x8;
 
 #if defined(IPOD_COLOR) || defined(IPOD_4G) \
  || defined(IPOD_MINI)  || defined(IPOD_MINI2G)
@@ -85,33 +90,43 @@
 
 static bool usb_pin_detect(void)
 {
+    bool retval = false;
+    
 #if defined(IPOD_4G) || defined(IPOD_COLOR) \
  || defined(IPOD_MINI) || defined(IPOD_MINI2G)
     /* GPIO D bit 3 is usb detect */
     if (GPIOD_INPUT_VAL & 0x08)
-        return true;
+        retval = true;
 
 #elif defined(IPOD_NANO) || defined(IPOD_VIDEO)
     /* GPIO L bit 4 is usb detect */
     if (GPIOL_INPUT_VAL & 0x10)
-        return true;
+        retval = true;
 
 #elif defined(SANSA_C200)
     /* GPIO H bit 1 is usb detect */
     if (GPIOH_INPUT_VAL & 0x02)
-        return true;
+        retval = true;
 
 #elif defined(SANSA_E200)
     /* GPIO B bit 4 is usb detect */
     if (GPIOB_INPUT_VAL & 0x10)
-        return true;
+        retval = true;
 
 #elif defined(IRIVER_H10) || defined(IRIVER_H10_5GB)
     /* GPIO L bit 2 is usb detect */
     if (GPIOL_INPUT_VAL & 0x4)
-        return true;
+        retval = true;
 #endif
-    return false;
+
+    /* if USB is detected, re-enable the USB-device */
+    if (retval)
+    {
+        DEV_EN |= DEV_USB;
+        DEV_EN |= 0x8;
+    }
+    
+    return retval;
 }
 
 /* detect host or charger (INSERTED or POWERED) */
Index: ../firmware/target/arm/ipod/button-clickwheel.c
===================================================================
--- ../firmware/target/arm/ipod/button-clickwheel.c	(revision 15973)
+++ ../firmware/target/arm/ipod/button-clickwheel.c	(working copy)
@@ -92,15 +92,15 @@
     }
 
     GPIOB_OUTPUT_VAL |= 0x10;
-    DEV_EN |= 0x10000;
-    DEV_RS |= 0x10000;
+    DEV_EN |= DEV_OPTO;
+    DEV_RS |= DEV_OPTO;
     udelay(5);
-    DEV_RS &= ~0x10000; /* finish reset */
+    DEV_RS &= ~DEV_OPTO; /* finish reset */
 
     outl(0xffffffff, 0x7000c120);
     outl(0xffffffff, 0x7000c124);
     outl(0xc00a1f00, 0x7000c100);
-    outl(0x1000000, 0x7000c104);
+    outl(0x01000000, 0x7000c104);
 }
 
 static inline int ipod_4g_button_read(void)
@@ -122,13 +122,13 @@
 
         if ((status & 0x800000ff) == 0x8000001a) 
         {
-            if (status & 0x100)
+            if (status & 0x0100)
                 btn |= BUTTON_SELECT;
-            if (status & 0x200)
+            if (status & 0x0200)
                 btn |= BUTTON_RIGHT;
-            if (status & 0x400)
+            if (status & 0x0400)
                 btn |= BUTTON_LEFT;
-            if (status & 0x800)
+            if (status & 0x0800)
                 btn |= BUTTON_PLAY;
             if (status & 0x1000)
                 btn |= BUTTON_MENU;
@@ -342,7 +342,20 @@
     hold_button = button_hold();
 
     if (hold_button != hold_button_old)
+    {
         backlight_hold_changed(hold_button);
+        
+        if (hold_button)
+        {
+            /* lock -> disable wheel sensor */
+            DEV_EN &= ~DEV_OPTO;
+        }
+        else
+        {
+            /* unlock -> enable wheel sensor */
+            DEV_EN |= DEV_OPTO;
+        }
+    }
 
     /* The int_btn variable is set in the button interrupt handler */
     return int_btn;
Index: ../firmware/target/arm/ipod/power-ipod.c
===================================================================
--- ../firmware/target/arm/ipod/power-ipod.c	(revision 15973)
+++ ../firmware/target/arm/ipod/power-ipod.c	(working copy)
@@ -71,9 +71,15 @@
         GPIO_SET_BITWISE(GPIOJ_OUTPUT_VAL, 0x04);
 #elif defined(IPOD_VIDEO)
     if (on)
+    {
         GPO32_VAL &= ~0x40000000;
+        DEV_EN |= DEV_IDE0;
+    }
     else
+    {
+        DEV_EN &= ~DEV_IDE0;
         GPO32_VAL |= 0x40000000;
+    }
 #else /* Nano */
     (void)on;  /* Do nothing. */
 #endif