使用CDC类开发USB转RS232遇到的问题

只看该作者 · 2007-10-13 14:51

各位大侠：
小弟正在使用CDC类开发USB转RS232，但不知下面的CDC类的特殊描述符是什么意思？？？

/* The Configuration Descriptor */
CONST PACKED_USB_CONFIG_DESCR  PackedConfigDescr =
{
    9,                                      /* bLength */
    USB_CONFIGURATION_DESCRIPTOR_TYPE,      /* descriptor type */
    SWAP( PACKED_USB_CONFIG_DESCR_LEN ),    /* length of packed config descr. (16b) */
    0x02,                                   /* number of interfaces */
    0x01,                                   /* configuration value */
    0x00,                                   /* configuration string index (none) */
    0x80,                                   /* attributes (self-powered, no remote wakeup) */
    0x0A,                                   /* max power (0x0A * 2mA = 20mA) */

      // 通信接口
    /* Interface descriptor */
    9,                                      /* bLength */
    USB_INTERFACE_DESCRIPTOR_TYPE,          /* descriptor type */
    0x00,                                   /* interface number */
    0x00,                                   /* alternate setting */
    0x01,                                   /* number of endpoints (excl. EP0) */
    0x02,   /* CDC class */                 /* interface class (USBTMC=0xFE) */
    0x02,   /* Abstract (Modem) */          /* interface subclass (USB488=0x03) */
    0x01,   /* AT-Commands */               /* interface protocol (0x01)*/
    0x00,                                   /* interface string index (none) */

    /* CDC Class-Specific descriptor */
？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？
这里是什么意思？？？？？？？？？？？？？？？？？？？？？？？
    5,           /* sizeof(usbDescrCDC_HeaderFn): length of descriptor in bytes */
    0x24,        /* descriptor type */
    0,           /* header functional descriptor */
    0x10, 0x01,

    4,           /* sizeof(usbDescrCDC_AcmFn): length of descriptor in bytes */
    0x24,        /* descriptor type */
    2,           /* abstract control management functional descriptor */
    0x02,        /* SET_LINE_CODING,    GET_LINE_CODING, SET_CONTROL_LINE_STATE    */

    5,           /* sizeof(usbDescrCDC_UnionFn): length of descriptor in bytes */
    0x24,        /* descriptor type */
    6,           /* union functional descriptor */
    0,           /* CDC_COMM_INTF_ID */
    1,           /* CDC_DATA_INTF_ID */

    5,           /* sizeof(usbDescrCDC_CallMgtFn): length of descriptor in bytes */
    0x24,        /* descriptor type */
    1,           /* call management functional descriptor */
    0,           /* allow management on data interface, handles call management by itself */
    1,           /* CDC_DATA_INTF_ID */

    7,                                      /* bLength */
    USB_ENDPOINT_DESCRIPTOR_TYPE,           /* descriptor type */
    0x81,                                   /* Endpoint dir'n (IN) & addr */
    USB_ENDPOINT_TYPE_INTERRUPT,            /* Endpoint type */
    LO_BYTE( EP1_MAX_PACKET_SIZE ),         /* Maximum pkt size (16) */
    HI_BYTE( EP1_MAX_PACKET_SIZE ),
    10,                                     /* Polling interval (unit=frame=1mS) */

      // 数据接口
    /* Interface Descriptor  */
    9,           /* sizeof(usbDescrInterface): length of descriptor in bytes */
    4,           /* descriptor type */
    1,           /* index of this interface */
    0,           /* alternate setting for this interface */
    2,           /* endpoints excl 0: number of endpoint descriptors to follow */
    0x0A,        /* Data Interface Class Codes */
    0,
    0,           /* Data Interface Class Protocol Codes */
    0,           /* string index for interface */

    7,                                      /* bLength */
    USB_ENDPOINT_DESCRIPTOR_TYPE,           /* descriptor type */
    0x82,                                   /* Endpoint dir'n (IN) & addr */
    USB_ENDPOINT_TYPE_BULK,                 /* Endpoint type */
    LO_BYTE( EP2_MAX_PACKET_SIZE ),         /* Maximum pkt size (64) */
    HI_BYTE( EP2_MAX_PACKET_SIZE ),
    10,                                     /* Interval - usually ignored for bulk */

    7,                                      /* bLength */
    USB_ENDPOINT_DESCRIPTOR_TYPE,           /* descriptor type */
    0x02,                                   /* Endpoint dir'n (OUT) & addr */
    USB_ENDPOINT_TYPE_BULK,                 /* Endpoint type */
    LO_BYTE( EP2_MAX_PACKET_SIZE ),         /* Maximum pkt size (64) */
    HI_BYTE( EP2_MAX_PACKET_SIZE ),
    10,                                     /* Interval - usually ignored for bulk */
};