USB CDC ACM with AUDIO class on Windows

[abhipray]

I have successfully been using USB CDC ACM class alongside USB Audio with only a MIC feature available on Mac OS. However, on Windows, only USB CDC ACM enumerates in Device Manager. The Audio class enumerates with a failure "Device USB\VID****** had a problem starting". Any ideas what could be causing this discrepancy?

[Andrej102]

my code with the addition of IAD in the file "app_usbd_audio.c" not work (no usb audio device in windows):

#define USBD_AUDIO_CLASS				0x01
#define USBD_AUDIO_SUBCLASS_CONTROL			0x01
#define USBD_AUDIO_PROTOCOL_UNDEFINED			0x00
#define USBD_DSC_TYPE_INTERFACE_ASSOCIATION		0x0B

static bool audio_feed_descriptors(app_usbd_class_descriptor_ctx_t * p_ctx,
                                   app_usbd_class_inst_t const     * p_inst,
                                   uint8_t                         * p_buff,
                                   size_t                            max_size)
{
    static uint8_t ifaces   = 0;
    ifaces = app_usbd_class_iface_count_get(p_inst);
    ASSERT(ifaces == 2);
    app_usbd_audio_t const * p_audio = audio_get(p_inst);
//**
    static app_usbd_class_iface_conf_t const * p_cur_iface = NULL;
    p_cur_iface = app_usbd_class_iface_get(p_inst, 0);
//**

    APP_USBD_CLASS_DESCRIPTOR_BEGIN(p_ctx, p_buff, max_size);

    //********** IA insert ******************

    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x08); // bLength
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_DSC_TYPE_INTERFACE_ASSOCIATION);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(app_usbd_class_iface_number_get(p_cur_iface));
    APP_USBD_CLASS_DESCRIPTOR_WRITE(2);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_AUDIO_CLASS);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_AUDIO_SUBCLASS_CONTROL);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_AUDIO_PROTOCOL_UNDEFINED);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x00);

    //*****************************************

    /* CONTROL INTERFACE DESCRIPTOR */
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x09); // bLength
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_DESCRIPTOR_INTERFACE); // bDescriptorType = Interface

//    static app_usbd_class_iface_conf_t const * p_cur_iface = NULL;
//    p_cur_iface = app_usbd_class_iface_get(p_inst, 0);

    APP_USBD_CLASS_DESCRIPTOR_WRITE(app_usbd_class_iface_number_get(p_cur_iface)); // bInterfaceNumber
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x00); // bAlternateSetting
    APP_USBD_CLASS_DESCRIPTOR_WRITE(app_usbd_class_iface_ep_count_get(p_cur_iface)); // bNumEndpoints
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_AUDIO_CLASS); // bInterfaceClass = Audio
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_AUDIO_SUBCLASS_AUDIOCONTROL); // bInterfaceSubclass (Audio Control)
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_AUDIO_CLASS_PROTOCOL_UNDEFINED); // bInterfaceProtocol
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x00); // iInterface

    /* HEADER INTERFACE */

[Andrej102]

It works, I give the working code for nrf82540 and SDK v17b maybe it will help someone (to create a composite USB device USB AUDIO + CDC ACM, you need to add a descriptor  an "INTERFACE_ASSOCIATION DESCRIPTOR" (IAD) just before the "INTERFACE DESCRIPTOR" in the file "app_usbd_audio.c", in the function audio_feed_descriptors() at line 675,  for the AudioClass Control Interface):

#define USBD_AUDIO_CLASS				0x01
#define USBD_AUDIO_SUBCLASS_CONTROL			0x01
#define USBD_AUDIO_PROTOCOL_UNDEFINED			0x00
#define USBD_DSC_TYPE_INTERFACE_ASSOCIATION		0x0B

static bool audio_feed_descriptors(app_usbd_class_descriptor_ctx_t * p_ctx,
                                   app_usbd_class_inst_t const     * p_inst,
                                   uint8_t                         * p_buff,
                                   size_t                            max_size)
{
    static uint8_t ifaces   = 0;
    ifaces = app_usbd_class_iface_count_get(p_inst);
    ASSERT(ifaces == 2);
    app_usbd_audio_t const * p_audio = audio_get(p_inst);

    APP_USBD_CLASS_DESCRIPTOR_BEGIN(p_ctx, p_buff, max_size);

    static app_usbd_class_iface_conf_t const * p_cur_iface = NULL;
    p_cur_iface = app_usbd_class_iface_get(p_inst, 0);

    //********** IA insert ******************

    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x08); // bLength
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_DSC_TYPE_INTERFACE_ASSOCIATION);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(app_usbd_class_iface_number_get(p_cur_iface));
    APP_USBD_CLASS_DESCRIPTOR_WRITE(ifaces);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_AUDIO_CLASS);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_AUDIO_SUBCLASS_CONTROL);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(USBD_AUDIO_PROTOCOL_UNDEFINED);
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x00);

    //*****************************************

    /* CONTROL INTERFACE DESCRIPTOR */
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x09); // bLength
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_DESCRIPTOR_INTERFACE); // bDescriptorType = Interface

  //  static app_usbd_class_iface_conf_t const * p_cur_iface = NULL;
 //   p_cur_iface = app_usbd_class_iface_get(p_inst, 0);

    APP_USBD_CLASS_DESCRIPTOR_WRITE(app_usbd_class_iface_number_get(p_cur_iface)); // bInterfaceNumber
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x00); // bAlternateSetting
    APP_USBD_CLASS_DESCRIPTOR_WRITE(app_usbd_class_iface_ep_count_get(p_cur_iface)); // bNumEndpoints
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_AUDIO_CLASS); // bInterfaceClass = Audio
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_AUDIO_SUBCLASS_AUDIOCONTROL); // bInterfaceSubclass (Audio Control)
    APP_USBD_CLASS_DESCRIPTOR_WRITE(APP_USBD_AUDIO_CLASS_PROTOCOL_UNDEFINED); // bInterfaceProtocol
    APP_USBD_CLASS_DESCRIPTOR_WRITE(0x00); // iInterface

    /* HEADER INTERFACE */

[Andrej102]

As you can see from the above code

You will also need to move the lines:

static app_usbd_class_iface_conf_t const * p_cur_iface = NULL;
p_cur_iface = app_usbd_class_iface_get(p_inst, 0);

to before inserting.

and you can still add defines:

#define USBD_AUDIO_CLASS 0x01
#define USBD_AUDIO_SUBCLASS_CONTROL 0x01
#define USBD_AUDIO_PROTOCOL_UNDEFINED 0x00
#define USBD_DSC_TYPE_INTERFACE_ASSOCIATION 0x0B

[Andrej102]

Thank you very much abhipray