Initial code for USB cable detection

- Currently actual detection commented out due to issues

Output/pjrcUSB/arm/usb_dev.c

@@ -1098,12 +1098,17 @@ restart:
 
 
 
-void usb_init()
+uint8_t usb_init()
 {
 	#ifdef UART_DEBUG
 	print("USB INIT"NL);
 	#endif
 
+	// If no USB cable is attached, do not initialize usb
+	// XXX Test -HaaTa
+	//if ( USB0_OTGISTAT & USB_OTGSTAT_ID )
+	//	return 0;
+
 	// Clear out endpoints table
 	for ( int i = 0; i <= NUM_ENDPOINTS * 4; i++ )
 	{
@@ -1147,6 +1152,8 @@ void usb_init()
 
 	// enable d+ pullup
 	USB0_CONTROL = USB_CONTROL_DPPULLUPNONOTG;
+
+	return 1;
 }
 
 // return 0 if the USB is not configured, or the configuration