AN249 Silicon_Laboratories, AN249 Datasheet - Page 12

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

AN249
This item tells the host the maximum number of bytes that can be contained inside a single control endpoint
transfer. For low speed devices, this byte must be set to 8, while full speed devices can have maximum Endpoint 0
packet sizes of 8, 16, 32, or 64. EP0_PACKET_SIZE is defined in the F3xx_USB0_Descriptor.h header file.
Reports can be larger than the maximum packet size. In this case, the report will be transferred across multiple
packets.
This two-byte item identifies the Vendor ID for the device. Vendor IDs can be acquired through the USB.org
website. Devices using C8051F32x microcontrollers are allowed to use Silicon Laboratories’ Vendor ID, which is
0xC410, after applying for a Silicon Labs-issued PID.
Host applications will search attached USB devices’ Vendor IDs to find a particular device needed for an
application.
Like the Vendor ID, this two-byte item uniquely identifies the attached USB device. Product IDs can be acquired
through the USB.org web site. Alternatively, Silicon Laboratories has reserved a block of Product IDs to be used by
customers designing products with Silicon Laboratories USB products. Contact Silicon Laboratories technical
support to allocate one of these reserved Product IDs for your design. This service is free of charge.
This item is used along with the Vendor ID and the Product ID to uniquely identify each USB device.
The next three one-byte items tell the host which string array index to use when retrieving UNICODE strings
describing attached devices that are displayed by the system on-screen. This string describes the manufacturer of
the attached device. For example, the string could read “Silicon Laboratories.”
A string index value of 0x00 indicates to the host that the device does not have a value for this string stored in
memory.
This index will be used when the host wants to retrieve the string that describes the attached product. For example,
the string could read “USB Keyboard”.
The string pointed to by this index can contain the UNICODE text for the product’s serial number.
This item tells the host how many configurations the device supports. A configuration is the definition of the
device’s functional capabilities, including endpoint configuration. All devices must contain at least one
configuration, but more than one can be supported. For this example, only one configuration will be defined.
12
0xC410,
0x0000,
0x0000,
0x00,
0x00,
0x00,
0x01
// idVendor
// idProduct
// bcdDevice
// iManufacturer
// iProduct
// iSerialNumber
// bNumConfigurations
Rev. 0.2