I'm working with the usb_device_audio_generator example on the MIMXRT1060-EVK. As is, it works and I've been able to modify the audio data and the descriptor to change the PCM width and the audio bit rate; however, I have not had any luck getting multiple channels to work. I can get the audio to actually come out and it is split across 2 channels, but somehow it seems the feed rate is not correct. When I hook linux-ALSA up to it, I get buffer over/underruns.
In USB-HS Isochronous Audio, the packet rate is 8000 pkts per second, not fully understanding the entire flow yet, I would have assumed that I would be getting a USB-handler interrupt at that rate, but that's not what I see. Seems to be closer to about a 800-900 interrupts per second rather than 8000. I have not yet figured out if the data is buffered and pushed out by the USB hardware (which would explain why I don't need to be interrupted 8000 times per second) or if I am just doing something wrong.
Anyone working on anything like this?
I'm pretty new to this level of USB development, so any pointers on descriptor design sure would be appreciated.