The approach of the Media Transfer Protocol class addresses some weaknesses of the Mass Storage Device class. File-based communication allows access to the file system from the host system (PC) and the device at the same time.
Using the MTP class also allows selectively exposing content of the file system to the host system, typically a PC. Sudden removal of the USB cable does not endanger the data integrity of the device’s file system. On the device side any file system can be used, there is no need for a FAT-compatible file system. Even virtual files can be exchanged with the host via MTP.
“The Media Transfer Protocol class is a significant improvement to the way embedded systems transfer their data to a PC. Being able to select the exposed content and to use a FAT-free and therefore royalty-free file system such as emFile EFS are significant advantages for the developer of an embedded system,” says Dirk Akemann, Marketing Manager of Segger.
emUSB-Device is a high performance USB device stack specifically designed for embedded systems. The flexible device stack allows the creation of multi-class devices using nearly any combination of the provided classes. emUSB-Device provides classes for the Media Transfer Protocol, Mass Storage Device, CDROM, Human Interface Device, CDC (Serial port communication), printer and a sophisticated Bulk communication class. emUSB-Device is fully compliant to the USB-standard.
Segger designed its emFile to be a highly efficient file system optimised for resource usage and performance. Two versions are available, one for FAT-file systems and another for EFS, a proprietary file system which allows the use of long file names without royalties. emFile’s driver level is fail-safe by design, removing the risk of corrupted data. To add failsafety to the upper file-system, a highly efficient journaling option is available for both EFS and FAT. For security, encryption of either an entire volume or on a file-by-file basis with the highest encryption standards is