AN249 Silicon_Laboratories, AN249 Datasheet - Page 11

• Manufacturer Part Number: AN249
• Description: Human Interface Device Tutorial
• Manufacturer: Silicon_Laboratories

5.4.1. Device Descriptor
The template defines the Device Descriptor as follows:
{
};
The first item describes the descriptor length and should be common to all USB Device Descriptors.
0x01 is the constant one-byte designator for Device descriptors and should be common to all device descriptors.
This BCD-encoded two-byte item tells the system which USB specification release guidelines the device follows.
This number might need to be altered in devices that take advantage of additions or changes included in future
revisions of the USB specification, as the host will use this item to help determine what driver to load for the device.
If the USB device class is to be defined inside the device descriptor, this item would contain a constant defined in
the USB specification. However, this firmware template assumes that the device will be defined in other
descriptors. Device classes defined in other descriptors should set the Device Class item in the Device Descriptor
to 0x00.
If the Device Class item discussed above is set to 0x00, then the Device Sub Class item should also be set to
0x00. This item can tell the host information about the device’s subclass setting.
This item can tell the host whether the device supports high speed transfers. If the above two items are set to 0x00,
this one should also be set to 0x00.
18,
0x01,
0x1001,
0x00,
0x00,
0x00,
EP0_PACKET_SIZE, // bMaxPacketSize0
0xC410,
0x0000,
0x0000,
0x00,
0x00,
0x00,
0x01
18,
0x01,
0x1001,
0x00,
0x00,
0x00,
EP0_PACKET_SIZE,
// bLength
// bDescriptorType
// bcdUSB
// bDeviceClass
// bDeviceSubClass
// bDeviceProtocol
// idVendor
// idProduct
// bcdDevice
// iManufacturer
// iProduct
// iSerialNumber
// bNumConfigurations
// bLength
// bDescriptorType
// bcdUSB
// bDeviceClass
// bDeviceSubClass
// bDeviceProtocol
// bMaxPacketSize0
Rev. 0.2
AN249
11