Required HID Descriptors

This topic describes required Human Interface Devices (HID) descriptors for the Windows Precision Touchpad HID protocol implementation.

Required USB HID Descriptor

The following table shows the required USB HID descriptor. For more information, see section 6.2.1 in Device Class Definition for Human Interface Devices (HID) Version 1.11.

Table 1 USB HID Descriptor Members

Member Size in bytes Description
bLength 1 Size of the descriptor
bDescriptorType 1 Type of descriptor
bcdHID 2 HID version number
bCountryCode 1 Country code
bNumDescriptors 1 Number of descriptors
bDescriptorType 1 Descriptor type
bDescriptorLength 2 Length of the descriptor

Required I²C HID Descriptor

The following table shows the required I²C HID descriptor.

Table 2 HID I2C Descriptor Members

Member Size in bytes Description
wHIDDescLength 2 The length of the complete HID descriptor (in Bytes)
bcdVersion 2 The version number, in binary coded decimal (BCD) format
wReportDescLength 2 The length of the Report descriptor (in Bytes)
wReportDescRegister 2 The register index containing the Report descriptor
wInputRegister 2 The register number to read the input report (in unsigned Bytes)
wMaxInputLength 2 The length of the largest input report to be read from the input register
wOutputRegister 2 The register number to send the output (in unsigned Bytes)
wMaxOutputLength 2 The length of the largest output report to be sent
wCommandRegister 2 The register number to send command requests (in unsigned Bytes)
wDataRegister 2 The register number to exchange data with command requests (in unsigned Bytes)
wVendorID 2 USB-IF assigned Vendor ID
wDeviceID 2 Device ID
wVersionID 2 Firmware version number

Required Device Attributes

The following HID properties must be provided in the device attributes. The reporting of these device attributes is bus specific. Consult the HID specific guidance for your choice of bus.

Table 3 Required Device Attribute Members

Member Description USB I²C
wVendorID Vendor ID idVendor in USB Device Descriptor wVendorID in I²C HID Descriptor (see above)
wProduct Product ID idProduct in USB Device Descriptor wDeviceID in I²C HID Descriptor (see above)
wVersionID Firmware version number bcdDevice in USB Device Descriptor wVersionID I²C HID Descriptor (see above)