Implementing USB Media Transfer Protocol

RE: Implementing USB Media Transfer Protocol

peterz — Sun, 28 Mar 2021 20:58:05 GMT

I'm also interested in MTP for several reasons. With MTP I could
a) deliver status and get/set config of my device as text file
b) present sensor result values as "temperature_2021-03-28.csv" and "temperature_2021-03-28.json" and produce/format the file content on the fly
c) firmware update for dummies (just drop the file)

Yes, most could also be done with MSC.
But files "popping up" when a measurement is terminated is not possible when the host OS is the boss of the file system.
And detach/reattach for every change will lead to "drive not present" when an application wants to check for new results regularly.

I looked at the above mentioned code from Bosch. This is clearly a good solution in the Bosch context. But IMHO this implementation does not fit with the concepts of nRF52 SDK. I would much prefer an approach which adopts the existing concepts and integrates smoothly with the Nordic library. So I started with the Nordic CDC implementation and adapted the code to reflect MTP instead of CDC.

I'm a newbie in MTP and not experienced in USB either, therefore I progress very slowly and the resulting code is of questionable quality.
But if somebody wants to join the effort, I'll put the evolving code in a git repository.
(or just wait a couple of weeks until it starts to work...)

have fun
Peter

EDIT 17.04.2021: now I can list files and read a dummy text file on Linux and Windows 10. Making it work on Linux did take some effort but it was a piece of cake compared to make the same work on Windows.

RE: Implementing USB Media Transfer Protocol

Jabez Winston — Sun, 02 Aug 2020 07:00:18 GMT

Please have a look at the USB MTP implementation for nRF52840 by Bosch Sensortec

https://github.com/Zhyolo/COINES/tree/master/coines_api/mcu_app30/usb_mtp

RE: Implementing USB Media Transfer Protocol

Sreejit — Wed, 08 Jul 2020 08:28:21 GMT

Hi Soren,

We too are trying to write data to SD card while the USB interface is copying the data out. Can I know what was the result of your evaluation. Were you able to achieve the required functionality?

RE: Implementing USB Media Transfer Protocol

Soren Bendtsen — Thu, 23 Apr 2020 12:54:26 GMT

Thanks Kenneth!

Its not the answer I was looking for, but appreciate you taking the time.

I am looking at if something like this could be ported. It would need to be modified for the file system and usb driver, but it could be do-able.

https://github.com/libmtp/libmtp/tree/master/src

RE: Implementing USB Media Transfer Protocol

Kenneth — Thu, 23 Apr 2020 12:40:58 GMT

Not aware of such example now, I don't really have any suggestion for workaround either.

Best regards,
Kenneth