USBD_CUSTOM_HID

  if (USBD_RegisterClass(&hUsbDeviceFS, &USBD_CUSTOM_HID) != USBD_OK)
  {
    Error_Handler();
  }

USBD_ClassTypeDef  USBD_CUSTOM_HID =
{
  USBD_CUSTOM_HID_Init,
  USBD_CUSTOM_HID_DeInit,
  USBD_CUSTOM_HID_Setup,
  NULL, /*EP0_TxSent*/
  USBD_CUSTOM_HID_EP0_RxReady, /*EP0_RxReady*/ /* STATUS STAGE IN */
  USBD_CUSTOM_HID_DataIn, /*DataIn*/
  USBD_CUSTOM_HID_DataOut,
  NULL, /*SOF */
  NULL,
  NULL,
  USBD_CUSTOM_HID_GetHSCfgDesc,
  USBD_CUSTOM_HID_GetFSCfgDesc,
  USBD_CUSTOM_HID_GetOtherSpeedCfgDesc,
  USBD_CUSTOM_HID_GetDeviceQualifierDesc,
};
 uint8_t (*Init)(struct _USBD_HandleTypeDef *pdev, uint8_t cfgidx);

static uint8_t  USBD_CUSTOM_HID_Init(USBD_HandleTypeDef *pdev,
                                     uint8_t cfgidx)

/* USB Device handle structure */
typedef struct _USBD_HandleTypeDef
{
  uint8_t                 id;
  uint32_t                dev_config;
  uint32_t                dev_default_config;
  uint32_t                dev_config_status;
  USBD_SpeedTypeDef       dev_speed;
  USBD_EndpointTypeDef    ep_in[16];
  USBD_EndpointTypeDef    ep_out[16];
  uint32_t                ep0_state;
  uint32_t                ep0_data_len;
  uint8_t                 dev_state;
  uint8_t                 dev_old_state;
  uint8_t                 dev_address;
  uint8_t                 dev_connection_status;
  uint8_t                 dev_test_mode;
  uint32_t                dev_remote_wakeup;

  USBD_SetupReqTypedef    request;
  USBD_DescriptorsTypeDef *pDesc;
  USBD_ClassTypeDef       *pClass;
  void                    *pClassData;
  void                    *pUserData;
  void                    *pData;
} USBD_HandleTypeDef;