AN249 Silicon_Laboratories, AN249 Datasheet - Page 16

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

AN249
5.4.5. OUT Endpoint Descriptor
HID-class devices are not required to use an OUT Endpoint. The firmware template declares an OUT Endpoint in
case custom systems require one. Most item values in this descriptor will be identical to the IN Endpoint descriptor.
The descriptor is defined as follows:
{
}
This item describes the size of the descriptor.
0x05 is the constant one-byte designator for Endpoint descriptors.
This item configures the endpoint to be OUT at address 02.
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. EP2_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. For the firmware template, which transfers data full
speed rates, the units for bInterval are 125 ms. This descriptor defines a polling speed of 125 ms x 10 or once
every 1.25 seconds.
16
0x07,
0x05,
0x02,
0x03,
EP2_PACKET_SIZE_LE,
10
0x07,
0x05,
0x02,
0x03,
EP2_PACKET_SIZE_LE,
10
// bmAttributes
// bInterval
// bLength
// bDescriptorType
// bEndpointAddress
// MaxPacketSize (LITTLE ENDIAN)
// bLength
// bDescriptorType
// bEndpointAddress
// bmAttributes
// MaxPacketSize (LITTLE ENDIAN)
// bInterval
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