Specifications

V850E2/MN4 USB CDC (Communication Device Class) Driver
R01AN0010EJ0101 Rev.1.01 Page 14 of 117
Feb 01, 2012
3.5.2 Formats
The size and field structure of descriptors varies depending on the descriptor type as summarized in the tables below.
The data in each field is arranged in little endian format.
Table 3.4 Device Descriptor Format
Field
Size
(Bytes) Description
bLength 1 Size of the descriptor
bDescriptorType 1 Type of the descriptor
bcdUSB 2 Release number of the USB specification
bDeviceClass 1 Class code
bDeviceSubClass 1 Subclass code
bDeviceProtocol 1 Protocol code
bMaxPacketSize0 1 Maximum packet size of Endpoint0
idVendor 2 Vendor ID
idProduct 2 Product ID
bcdDevice 2 Device release number
iManufacturer 1 Index of the string descriptor describing the manufacturer
iProduct 1 Index of the string descriptor describing the product
iSerialNumber 1 Index of the string descriptor describing the device’s serial number
bNumConfigurations 1 Number of configurations
Remarks: Vendor ID: Identification number that the vendor who is to develop a USB device acquires from
USB-IF
Product ID: Identification number that the vendor assigns to each of its products after acquiring a
vendor ID.
Table 3.5 Configuration Descriptor Format
Field
Size
(Bytes) Description
bLength 1 Size of the descriptor
bDescriptorType 1 Type of the descriptor
wTotalLength 2
Total number of bytes of the configuration, interface, and endpoint
descriptors
bNumInterfaces 1 Number of interfaces supported by this configuration
bConfigurationValue 1 Identification number of this configuration
iConfiguration 1 Index of the string descriptor describing this configuration
bmAttributes 1 Characteristics of this configuration
bMaxPower 1 Maximum consumption current of this configuration (in 2 μA units)