USB Promoter Group Adds New Type-C Specifications

New USB specifications have been released by the USB 3.0 Promoter Group, and are now available to download from They are USB Power Delivery v2.0 and USB Billboard Device Class v1.0 – said to be ‘essential’ for the development and implementation of new Alternative Modes (Display Monitor Vol 21 No 38) for USB-C.

The new Power Delivery (PD) specification updates USB PD v1.0 to meet the requirements of USB-C, and incorporate additional changes. If a USB-C host or device supports Alt Modes, they will use USB PD ‘Structured Vendor Defined Messages’ (Structured VDMs) to discover, configure and enter/exit Alt Modes. The USB PD Structured VDMs are defined to extend the functionality a device exposes. They provide a standard method to identify the Alt Modes a device supports, and to command it to enter/exit Alt Modes.

The USB Billboard Device Class specification outlines the methods used to communicate if an Alt Mode is supported by a host or device that is USB-C-capable. ‘In particular, if a device fails to successfully enter an Alternate Mode then the device will minimally expose a USB 2.0 Billboard interface powered by VBUS’, says the Promoter Group.