AN249 Silicon_Laboratories, AN249 Datasheet - Page 15

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

This item tells the host the string index of the Interface String that describes the specifics of the interface and can
be displayed on-screen. The firmware template defines no such string, and so sets the index to 0x00.
5.4.4. IN Endpoint Descriptor
The firmware template defines the IN Endpoint Descriptor as follows:
{
}
This item defines the length of this endpoint descriptor.
0x05 is the constant one-byte designator for Endpoint descriptors.
This item describes the address and data flow direction of the endpoint. Bits 0 through 3 define the endpoint’s
address, and bit 7 describes the data flow direction, with 1 meaning IN and 0 meaning OUT. The item in this
descriptor defines an “IN” endpoint with Endpoint Address 1.
This item describes the type of data transfer the device is configured to use. “0x03” designates this endpoint as
using the Interrupt data transfer method.
This item tells the host the maximum packet size for the endpoint. The maximum packet size should be at least as
large as the largest Report. EP1_PACKET_SIZE_LE is defined in the F3xx_USB0_Descriptor.h header file.
The value contained in this item determines how often the endpoint will be polled for data by the system software.
Units of the value vary depending on the speed of the device.
0x07,
0x05,
0x81,
0x03,
EP1_PACKET_SIZE_LE,
10 // bInterval
0x07,
0x05,
0x81,
0x03,
EP1_PACKET_SIZE_LE,
10
// bInterval
// bLength
// bDescriptorType
// bEndpointAddress
// bmAttributes
// MaxPacketSize (LITTLE ENDIAN)
// bLength
// bDescriptorType
// bEndpointAddress
// bmAttributes
// MaxPacketSize (LITTLE ENDIAN)
Rev. 0.2
AN249
15