RE: Custom USB device shows up as 2 separate devices when driver not installed

JoEi — Mon, 12 Sep 2022 14:51:11 GMT

Hi Håkon,

I just found the culprit.

The problem was that bDeviceClass was set to 0. This resulted in this strange behaviour.
After changing bDeviceClass to 0xFF it works fine, even installing the device driver works smoothly now.

When initially developing the bridge we knew about this difference but didn't think that it would cause such a problem.
Back then we also didn't want to modify the SDK but as it seems we need to do just that.

Thanks for the tip with lsusb. Because of this we saw that bDeviceClass is the only difference.

My solution is the following:
Changing APP_USBD_CODE_DEVICE_DESCRIPTOR in app_usbd_core.c to:

#define APP_USBD_CORE_DEVICE_DESCRIPTOR  {                                                               \
   .bLength = sizeof(app_usbd_descriptor_device_t),    /* descriptor size */                             \
   .bDescriptorType = APP_USBD_DESCRIPTOR_DEVICE,      /* descriptor type */                             \
   .bcdUSB = APP_USBD_BCD_VER_MAKE(2,0,0),             /* USB BCD version: 2.0 */                        \
   .bDeviceClass = APP_USBD_DEVICE_CLASS,              /* device class */                                \
   .bDeviceSubClass = APP_USBD_DEVICE_SUB_CLASS,       /* device subclass */                             \
   .bDeviceProtocol = APP_USBD_DEVICE_PROTOCOL,        /* device protocol */                             \
   .bMaxPacketSize0 = NRF_DRV_USBD_EPSIZE,             /* endpoint size: fixed to: NRF_DRV_USBD_EPSIZE*/ \
   .idVendor = APP_USBD_VID,                           /* Vendor ID*/                                    \
   .idProduct = APP_USBD_PID,                          /* Product ID*/                                   \
   .bcdDevice = APP_USBD_BCD_VER_MAKE(                 /* Device version BCD */                          \
       APP_USBD_DEVICE_VER_MAJOR,                                                                        \
       APP_USBD_DEVICE_VER_MINOR,                                                                        \
       APP_USBD_DEVICE_VER_SUB),                                                                         \
   .iManufacturer = APP_USBD_STRING_ID_MANUFACTURER,   /* String ID: manufacturer */                     \
   .iProduct = APP_USBD_STRING_ID_PRODUCT,             /* String ID: product */                          \
   .iSerialNumber = APP_USBD_STRING_ID_SERIAL,         /* String ID: serial */                           \
   .bNumConfigurations = 1                             /* Fixed value: only one configuration supported*/\
}

and adding these lines to sdk_config.h:

#ifndef APP_USBD_DEVICE_CLASS
#define APP_USBD_DEVICE_CLASS 0xFF
#endif

#ifndef APP_USBD_DEVICE_SUB_CLASS
#define APP_USBD_DEVICE_SUB_CLASS 0x00
#endif

#ifndef APP_USBD_DEVICE_PROTOCOL
#define APP_USBD_DEVICE_PROTOCOL 0x00
#endif

Kind regards,
Johannes

RE: Custom USB device shows up as 2 separate devices when driver not installed

Håkon Alseth — Mon, 12 Sep 2022 10:47:33 GMT

Hi,

[quote user=""]Instead of showing up as one device it shows up as 2 devices with the name of the interfaces.[/quote]

Could you share more details on what happens?

On linux, you can enable verbose mode using lsusb to see the full descriptor:

lsusb -d VID:PID -v

Kind regards,

Håkon