Alternative to MSC device (MTP)

[Lukasz Przenioslo]

Posted on March 26, 2018 at 07:30

Hello there,

I was able to implement an MSC class device basing on external qspi flash memory (

https://community.st.com/message/190720-re-qspi-fatfs-usb-mass-storage?commentID=190720

).

It works, but after some research and testing i think that this is not the right USB device class for the application. The goal is to be able to modify files in the system within it by the MCU (FatFS) and by the user using connected PC through USB. The problem here is that both systems (FatFS and USB MSC) implemet their own filesystems, thus they both operate on raw flash memory. this is not good, as I am having hard time hard time making this thread safe, as the USB components operate purely on interrupt routines. Instead, it would be beneficial to make the USB host PC to use the internal FatFS. The only idea how to do it I got now, is using USB CDC and implementing all communication + PC app by myself. I would like to avoid that.

I have noticed an USB class that might fit into this application but I am not sure how is it called and either it is proprietary at any point. I noticed it after I connect my Android phone to the PC:

This has to be something different than MSC. Also the phones operating system is just fine with me modifying the files there from my PC. Because of that I believe this is the kind of USB class designed for such application. The question is what is it and how can one implement it in STM32?

I would appreciate all help.

#msc #cdc #usb

[Lukasz Przenioslo]

Posted on March 26, 2018 at 08:39

Hello,

I have found out that the class I am looking for is MTP (Media transfer protocol). I wass all happy after I found this document and started reading about itL

http://www.st.com/resource/en/user_manual/dm00105256.pdf

 

It was a matter of time since I noticed that this class is available only for HOST's not DEVICE's. Thats a pitty...

[James Murray]

Posted on April 04, 2018 at 02:02

According to the Wikipedia pages about MTP it seems to be less standard that MSC and may require special drivers at the PC end. If this is incorrect please let me know!

I'd like to use it for the same reasons as you do, but the driver-less usage of MSC is more important for me.

James

[Tesla DeLorean]

Posted on April 04, 2018 at 03:12

Microsoft used MTP heavily with their media players circa 2005-2006

[Lukasz Przenioslo]

Posted on April 04, 2018 at 07:08

I am not sure about Linux but in Windows they are standard and installed automatically from windows update afaik. But I bet they are available in Linux as well:

https://wiki.archlinux.org/index.php/MTP

Did you guys maybe found any available device MTP drivers for STM32? The only ones I found are proprietary. Any chance ST team planning to write this dirver

DAHMEN.IMEN

‌ ?

[Imen.D]

Posted on April 04, 2018 at 11:12

Hello,

In fact, the MTP device is under USB roadmap. But, currently, there is no short term planning defined yet.

Best Regards,

Imen

[Imen.D]

Posted on April 04, 2018 at 10:39

Hello

Przenioslo.Lukasz

,

I will check your request internally with the appropriate team and come back to youasap.

Best Regards,

Imen

[Lukasz Przenioslo]

Posted on April 06, 2018 at 08:22

I would appreciate an update if anything moves forward in this manner. If You will need any testers for this new driver let me know

DAHMEN.IMEN

‌