USB Audio SOF

[abhipray]

I'm using SDK 15.2 and trying to set up a USB mic class. I am having trouble getting the SOF audio interrupt to fire.

I initialize the app_usbd module with the configuration for enable_sof set to true. I register an sof event handler with app_usbd_audio_sof_interrupt_register() like in the SDK USB Audio example which sets it up for headphones. The SOF event never triggers my sof event handler for the microphone. Instead, I do get SOF events inside usbd user event handler where I can start audio transmission. I have tried this with APP_USBD_CONFIG_SOF_HANDLING_MODE set to 1 (compress queue) as well as 2 (Interrupt). 

Am I missing some configuration?

[Kenneth]

Hello,

Can you share code and config?

Are you getting SOF events in hp_audio_user_ev_handler instead of hp_sof_ev_handler?

Best regards,
Kenneth

[abhipray]

Hi,

Unfortunately, I cannot share the code since it's tightly coupled with the rest of our system. I don't have a headphones class, only microphone. I am getting SOF events inside usbd_user_ev_handler().

Here are relevant pieces of code:

static void mic_sof_ev_handler(uint16_t framecnt);

/* Initialize the usbd library */
static const app_usbd_config_t usbd_config = {
.ev_state_proc = usbd_user_ev_handler, .enable_sof = true};
APP_ERROR_CHECK(app_usbd_init(&usbd_config));

app_usbd_class_inst_t const *class_inst_mic =
app_usbd_audio_class_inst_get(&m_app_audio_microphone);
APP_ERROR_CHECK(app_usbd_audio_sof_interrupt_register(class_inst_mic, mic_sof_ev_handler));
APP_ERROR_CHECK(app_usbd_class_append(class_inst_mic));

app_usbd_power_events_enable();

[Kenneth]

I have added this to internal Jira (NRFFOETT-2203), though I don't have an estimate of when the designers have time to look at it. For now my best suggestion is to try to workaround it in other ways.

Best regards,
Kenneth