USB设备描述符

USB描述符

USB通信开始之前，HOST需要通过模组提供的描述符来进行USB设备初始化，所以USB描述符是USB通信开始过程中非常重要的部分。描述符包括：设备描述符、配置描述符、接口描述符、端点描述符和字符串描述符（可选）。下面介绍YM310 X09模组提供的各个描述符详细内容。

模组是提供的是USB复合设备，目前软件提供的功能组合如下：

USB功能组合1：AT口 + LOG口（YM310.X09C_AT.S61/S62/S81版本）
USB功能组合2：网卡 + AT口 + LOG 口 (YM310.X09C_AT.S40/U61/U62版本)
USB功能组合3：网卡 + AT口 + LOG 口 + PPP口（YM310.X09C_AT.U60/YM310.X09S_AT.A60版本）

不用功能组合对应描述符值如下表，详细USB功能差异参考《AT软件介绍--AT版本列表》。

USB描述符

设备描述符

# 格式说明(其他描述符相同)
## 描述符类型
##     字段：内容(含义) #注释
##     字段：内容(含义) #注释
##     ...

DEVICE DESCRIPTOR ## 描述符类型
    bLength: 18   ## 字段：内容
    bDescriptorType: 0x01 (DEVICE)
    bcdUSB: 0x0200
    bDeviceClass: 0xef (Miscellaneous)
    bDeviceSubClass: 2
    bDeviceProtocol: 1 (Interface Association Descriptor)
    bMaxPacketSize0: 64
    idVendor: 0x19d1
    idProduct: 0x1003
    bcdDevice: 0x0200
    iManufacturer: 1
    iProduct: 2
    iSerialNumber: 3
    bNumConfigurations: 1

配置描述符

CONFIGURATION DESCRIPTOR
    bLength: 9
    bDescriptorType: 0x02 (CONFIGURATION)
    wTotalLength: 273
    bNumInterfaces: 8 # USB功能组合不同，该值会有差异
    bConfigurationValue: 1
    iConfiguration: 0
    Configuration bmAttributes: 0xa0 （NOT SELF-POWERED  REMOTE-WAKEUP）
    bMaxPower: 100  (200mA)

接口描述符

接口描述符体现了模组提供的USB功能，模组提供的接口（功能）如下：

网卡接口（ECM/RNDIS)

# 网卡接口描述符： 接口0&接口1 (本身是个复合接口，包含两个接口)
INTERFACE DESCRIPTOR (0.0): class Wireless Controller
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 0
    bAlternateSetting: 0
    bNumEndpoints: 1
    bInterfaceClass:  0xe0 (Wireless Controller)
    bInterfaceSubClass: 0x01
    bInterfaceProtocol: 0x03
    iInterface: 6
INTERFACE DESCRIPTOR (1.0): class CDC-Data
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 1
    bAlternateSetting: 0
    bNumEndpoints: 2
    bInterfaceClass: CDC-Data (0x0a)
    bInterfaceSubClass: 0x00
    bInterfaceProtocol: No class specific protocol required (0x00)
    iInterface: 0

AT口接口

# AT口接口描述符 接口2&接口3 (本身是个复合接口，包含两个接口)
INTERFACE DESCRIPTOR (2.0): class Communications and CDC Control
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 2
    bAlternateSetting: 0
    bNumEndpoints: 1
    bInterfaceClass: Communications and CDC Control (0x02)
    bInterfaceSubClass: Abstract Control Model (0x02)
    bInterfaceProtocol: AT Commands: V.250 etc (0x01)
    iInterface: 7
INTERFACE DESCRIPTOR (3.0): class CDC-Data
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 3
    bAlternateSetting: 0
    bNumEndpoints: 2
    bInterfaceClass: CDC-Data (0x0a)
    bInterfaceSubClass: 0x00
    bInterfaceProtocol: No class specific protocol required (0x00)
    iInterface: 0

LOG口接口

# LOG口接口描述符 接口4&接口5 (本身是个复合接口，包含两个接口)
INTERFACE DESCRIPTOR (4.0): class Communications and CDC Control
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 4
    bAlternateSetting: 0
    bNumEndpoints: 1
    bInterfaceClass: Communications and CDC Control (0x02)
    bInterfaceSubClass: Abstract Control Model (0x02)
    bInterfaceProtocol: AT Commands: V.250 etc (0x01)
    iInterface: 8
INTERFACE DESCRIPTOR (5.0): class CDC-Data
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 5
    bAlternateSetting: 0
    bNumEndpoints: 2
    bInterfaceClass: CDC-Data (0x0a)
    bInterfaceSubClass: 0x00
    bInterfaceProtocol: No class specific protocol required (0x00)
    iInterface: 0

PPP口接口

# PPP口接口描述符 接口6&接口7 (本身是个复合接口，包含两个接口)
INTERFACE DESCRIPTOR (6.0): class Communications and CDC Control
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 6
    bAlternateSetting: 0
    bNumEndpoints: 1
    bInterfaceClass: Communications and CDC Control (0x02)
    bInterfaceSubClass: Abstract Control Model (0x02)
    bInterfaceProtocol: AT Commands: V.250 etc (0x01)
    iInterface: 9
INTERFACE DESCRIPTOR (7.0): class CDC-Data
    bLength: 9
    bDescriptorType: 0x04 (INTERFACE)
    bInterfaceNumber: 7
    bAlternateSetting: 0
    bNumEndpoints: 2
    bInterfaceClass: CDC-Data (0x0a)
    bInterfaceSubClass: 0x00
    bInterfaceProtocol: No class specific protocol required (0x00)
    iInterface: 0

端点描述符

端点描述符是每个接口用到的端点集合，一个接口用到了三个端点，分别对应INT（中断）、OUT（输出）、IN（输入）。下面按照USB功能组合来列举端点分配情况： * USB功能组合1：AT口 + LOG口

# AT口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x81  IN  Endpoint:1
    bmAttributes: 0x03
        .... ..11 = Transfertype: Interrupt-Transfer (0x3)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x01  OUT  Endpoint:1
    bmAttributes: 0x02
        .... ..10 = Transfertype: Bulk-Transfer (0x2)
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x82  IN  Endpoint:2
    bmAttributes: 0x02
        .... ..10 = Transfertype: Bulk-Transfer (0x2)
    wMaxPacketSize: 512
    bInterval: 0

# LOG口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x83  IN  Endpoint:3
    bmAttributes: 0x03
        .... ..11 = Transfertype: Interrupt-Transfer (0x3)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x02  OUT  Endpoint:2
    bmAttributes: 0x02
        .... ..10 = Transfertype: Bulk-Transfer (0x2)
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x84  IN  Endpoint:4
    bmAttributes: 0x02
        .... ..10 = Transfertype: Bulk-Transfer (0x2)
    wMaxPacketSize: 512
    bInterval: 0

USB功能组合2：网卡 + AT口 + LOG 口

# 网卡INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x81  IN  Endpoint:1
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 8
    bInterval: 14
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x01  OUT  Endpoint:1
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x82  IN  Endpoint:2
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0

# AT口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x83  IN  Endpoint:3
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x02  OUT  Endpoint:2
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x84  IN  Endpoint:4
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0

# LOG口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x85  IN  Endpoint:5
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x03  OUT  Endpoint:3
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x86  IN  Endpoint:6
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0

USB功能组合3：网卡 + AT口 + LOG 口 + PPP口

# 网卡INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x81  IN  Endpoint:1
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 8
    bInterval: 14
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x01  OUT  Endpoint:1
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x82  IN  Endpoint:2
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0

# AT口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x83  IN  Endpoint:3
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x02  OUT  Endpoint:2
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x84  IN  Endpoint:4
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0

# LOG口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x85  IN  Endpoint:5
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x03  OUT  Endpoint:3
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x86  IN  Endpoint:6
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0

# PPP口INT&IN&OUT端点
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x87  IN  Endpoint:7
    bmAttributes: 0x03 (Transfertype: Interrupt-Transfer)
    wMaxPacketSize: 16
    bInterval: 16
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x04  OUT  Endpoint:4
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0
ENDPOINT DESCRIPTOR
    bLength: 7
    bDescriptorType: 0x05 (ENDPOINT)
    bEndpointAddress: 0x88  IN  Endpoint:8
    bmAttributes: 0x02
    wMaxPacketSize: 512
    bInterval: 0