Extend the automatic serial number descriptor code to read out and send all 10 bytes (20 characters) of the internal serial number on supported AVRs, rather than just the first 6 bytes (12 characters).

LUFA/Drivers/USB/LowLevel/DevChapter9.c

@@ -232,7 +232,7 @@ static void USB_Device_GetInternalSerialDescriptor(void)
 	struct
 	{
 		USB_Descriptor_Header_t Header;
-		int16_t                 UnicodeString[12];
+		int16_t                 UnicodeString[20];
 	} SignatureDescriptor;
 	
 	uint8_t SigReadAddress  = 0x0E;
@@ -246,7 +246,7 @@ static void USB_Device_GetInternalSerialDescriptor(void)
 		SignatureDescriptor.Header.bDescriptorType = DTYPE_String;
 	#endif
 
-	for (uint8_t SerialCharNum = 0; SerialCharNum < 12; SerialCharNum++)
+	for (uint8_t SerialCharNum = 0; SerialCharNum < 20; SerialCharNum++)
 	{
 		uint8_t SerialByte = boot_signature_byte_get(SigReadAddress);
 		

Projects/Magstripe/Descriptors.c

@@ -93,7 +93,7 @@ USB_Descriptor_Device_t PROGMEM DeviceDescriptor =
 		
 	.ManufacturerStrIndex   = 0x01,
 	.ProductStrIndex        = 0x02,
-	.SerialNumStrIndex      = NO_DESCRIPTOR,
+	.SerialNumStrIndex      = USE_INTERNAL_SERIAL,
 		
 	.NumberOfConfigurations = 1
 };