nRF52840 USB Cancel IN Transfer

RE: nRF52840 USB Cancel IN Transfer

George Beckstien — Tue, 12 Mar 2019 19:01:52 GMT

I merged in errata changes and workarounds from SDK15.3 to the nrf_drv_usbd.c used by Mbed-OS. I am still seeing the wrong packet being sent every now and then in this same situation.

What exactly does the workaround do in the nrfx_usbd_ep_abort() implementation you linked to? It does not seem to always "disarm" a "loaded" IN endpoint transfer.

I am running automated tests and 22 out of 100 iterations had a failure caused by this issue. This was on a hub that connected thru a dock thru thunderbolt 3. I am now testing with the DUT directly connected to my laptop and will let you know what the new results are.

RE: nRF52840 USB Cancel IN Transfer

George Beckstien — Thu, 28 Feb 2019 00:05:57 GMT

I will certainly suggest that when Mbed-OS upgrades the Nordic SDK next.

RE: nRF52840 USB Cancel IN Transfer

masz — Wed, 27 Feb 2019 14:38:29 GMT

Consider switching to nrfx if you don't use SDK stack.

RE: nRF52840 USB Cancel IN Transfer

George Beckstien — Wed, 27 Feb 2019 13:52:32 GMT

Ah! Mbed is currently using SDK14.2 and I only pulled in changes from 15.2 that were related to errata! I will go through the SDK15.2 driver and pull in other relevant changes... Mbed will eventually be transitioning to SDK15+ but it hasn't happened yet.

I figured it would be some sort of undocumented register manipulation.

Thank you masz and Einar! That should be exactly what I'm looking for. Hopefully it fixes this issue

RE: nRF52840 USB Cancel IN Transfer

Einar Thorsrud — Wed, 27 Feb 2019 13:48:19 GMT

Hi George Beckstien,

I have asked masz from the SDK low level driver development team to help answering your questions in this thread.

RE: nRF52840 USB Cancel IN Transfer

masz — Wed, 27 Feb 2019 13:41:19 GMT

Hi Geroge,

Aborting IN transfers is used in the SDK and implemented in hid_generic_clear_buffer() function. You probably need to use nrfx_usbd_ep_abort(nrfx_usbd_ep_t ep), see here for the description.

RE: nRF52840 USB Cancel IN Transfer

George Beckstien — Tue, 26 Feb 2019 14:59:46 GMT

Hi Einar,

I am actually working on contributing the USB implementation to Mbed-OS for the nRF52840. This is not an issue with Mbed. The issue is that the Nordic USB hardware does not present a clear way to cancel an auto-ACK on an IN endpoint after a DMA transfer has been completed.

The test only passes intermittently, presumably when the DMA transfer is fast enough to overwrite the old data before the new data is requested by the host.

Is there some way I can get support from Nordic in implementing the USB HAL for Mbed-OS? The implementation is very close to done, there are just a few more bugs to iron out.

Please let me know if there is a way I can converse with Nordic engineers via email.

Thank you

RE: nRF52840 USB Cancel IN Transfer

Einar Thorsrud — Tue, 26 Feb 2019 12:29:00 GMT

Hi,

I recommend you ask about this in the mbed forums, as you will probably get much better feedback on it there. (The mbed USB stack is not used in the nRF5 SDK, so we do not have much experience with it).