UBS MIDI implementation with SDK 15.0.0 and 15.2.0

[joneves]

Hi,

I'm trying to implement USB MIDI class so my Nordic nRF52840 PDK is recognized as a USB MIDI controller (using the nRF52 USB port).

I followed Edvin advice here. At the beginning it was not working and I realize that none of the USB examples was working has supposed, even with no modifications on the examples.

After a research I found out here that the problem was that I was using the SDK 15.3.0 when my DK uses the PCA10056 V0.9.0. According to the link there are some new modifications on the V1.0 and the SDK 15.3 is not compatible with PCA10056 versions earlier than the V1.0.

So I decided to try out the examples using previous SDKs. All work ok.

I went back to Edvins advice and starting from the USBD audio example I changed the APP_USBD_AUDIO_SUBCLASS_AUDIOSTREAMING to APP_USBD_AUDIO_SUBCLASS_MIDISTREAMING. With no more modifications I checked if the nRF USB of my DK was being recognized as a USB MIDI device on my computer. Indeed it was (using the SDK 15.0.0 at the time).

I tried out to use the same method using the SDK 15.2.0 and it didn't work, so I went back to the SDK 15.0.0. But it didn't work this time and since then I'm not able to put it working again anyway. Although - since I'm only modifying the microphone - the DK appears on the list of audio outputs for my computer.

My questions are: Why did it recognized once as a MIDI device and not anymore? Is it related with the fact that I didn't setup any MIDI defines? Or is it related with bugs of the version 0.9 of the PCA (as described here and here)?

Thanks for the support!

[Sigurd]

Hi,

There is a bug in SDK 15.0 when it comes to applying the USBD errata workarounds, see this and this post. 

That said, I strongly recommend buying a new nRF52840-DK, as the preview kits contains early engineering samples before the chip was qualified and put to production.

[joneves]

Thank you for your answer.

I'm actually waiting to test on a new nRF52840-DK. I'm only try to troubleshoot and understand if the problem is also on my implementation.

I followed the advice on the links that you sent me (using the SDK 15.0.0) and replaced that 0x10 with 0x20. Anyway it still doesn't work.

Can this be related with the bug of the DK that I'm testing or on this way it should work and it's a problem of my implementation?

[Sigurd]

joneves said:

Can this be related with the bug of the DK that I'm testing or on this way it should work and it's a problem of my implementation?

It could be both. But since the PDK v0.9.0 uses the very first Engineering A version of the chip, it could definitely be causing these issues.

Let me know how it goes when you get your nRF52840-DK.