typedef struct {
    usb_device_t dev; /**< USB device */
    /**< An OUT endpoint if in device mode, an IN endpoint otherwise */
    uint8_t rx_addr;
    /**< An IN endpoint if in device mode, an OUT endpoint otherwise */
    uint8_t tx_addr;
    srl_device_type_t type;
    srl_device_subtype_t subtype;
    ring_buf_ctrl_t rx_buf;
    ring_buf_ctrl_t tx_buf;
    srl_error_t err;
    uint16_t idvendor;
    uint16_t idproduct;
    uint16_t bcddevice;
    uint8_t baudtype;
    uint8_t reserved[9];
} srl_device_t;