Unified Display Interface

Unified Display Interface

Type	Digital video connector
Production history
Designer	Unified Display Interface Work Group
Designed	2006 (Cancelled 2007)
Produced	None
General specifications
Length	18.8 mm
Width	12.5 mm
Height	3.7 mm
Hot pluggable	Yes
External	Yes
Audio signal	No
Video signal	Yes
Pins	26
Electrical
Max. voltage	+5V
Max. current	0.5 A
Data
Data signal	R,G,B data + clock and display data channel (TMDS)
Width	36 bit (maximum)
Bitrate	16 Gbit/s
Pin out
Pin 1	Supply voltage for data link circutry	VDD_UDL
Pin 2	Supply voltage for data link circutry	VDD_UDL
Pin 3	Supply voltage for data link circutry	VDD_UDL
Pin 4	Supply voltage for data link circutry	VDD_UDL
Pin 5	Supply return for control and data link power	VSS
Pin 6	Supply return for control and data link power	VSS
Pin 7	Supply return for control and data link power	VSS
Pin 8	Supply return for control and data link power	VSS
Pin 9	Positive side of UDI lane 0 data (userd for x1 and x3 lane widths)	UDI_Data0+
Pin 10	Negative side of UDI lane 0 data (userd for x1 and x3 lane widths)	UDI_Data0-
Pin 11	Shield for UDI_Data0[-/-]	GND
Pin 12	Positive side of UDI lane 1 data (userd for x1 and x3 lane widths)	UDI_Data1+
Pin 13	Negative side of UDI lane 1 data (userd for x1 and x3 lane widths)	UDI_Data1-
Pin 14	Shield for UDI_Data1[-/-]	Ground
Pin 15	Positive side of UDI lane 2 data (userd for x1 and x3 lane widths)	UDI_Data2+
Pin 16	Negative side of UDI lane 1 data (userd for x1 and x3 lane widths)	UDI_Data2-
Pin 17	Shield for UDI_Data2[-/-]	GND
Pin 18	Reserved connector pin. No cable connection	(NC)
Pin 19	Reserved connector pin. No cable connection	(NC)
Pin 20	Reserved connector pin. No cable connection	(NC)
Pin 21		(Test Pin)
Pin 22	Ground return	GND
Pin 23	Supply voltage for control link signals	UDI_EPwr
Pin 24	UDI control link clock	UDI_CtrlClk
Pin 25	UDI Control link data	UDI_CtrlData
Pin 26	UDI link hot-plug detect	UDI_HPD

Unified Display Interface (UDI) was a digital video interface specification based on Digital Visual Interface (DVI). It was intended to be a lower cost implementation while providing compatibility with existing High-Definition Multimedia Interface (HDMI) and DVI displays. Unlike HDMI, which is aimed at high-definition multimedia consumer electronics devices such as television monitors and DVD players, UDI was specifically targeted towards computer monitor and video card manufacturers and did not support the transfer of audio data.

UDI was primarily backed by Intel with support from Samsung and other partners. In early 2007 Intel started supporting the similar DisplayPort standard, and both Intel and Samsung withdrew from the UDI SIG. There has been no announcements made about UDI since early 2007 and the UDI website is no longer operational.

Overview

UDI provides higher bandwidth than its predecessors (up to 16 Gbit/s in its first version, compared to 4.9 Gbit/s for HDMI 1.0) and incorporates a form of digital rights management known as HDCP. The connector has a single row of 26 contacts pitched 0.6 mm apart from each other, looking very similar to the USB plug which has a single row with only four contacts. Three of the 26 contacts will not be wired but are reserved for undetermined future upgrade possibilities. Transmit and receive plugs are slightly different, and a UDI cable will fit only one way. Bidirectional communication works at a much lower data rate than that available for the single direction video datastream.

On December 20, 2005, the UDI Special Interest Group (UDI SIG) was announced. They worked on determining the refined specifications and promoting the interface. Members included Apple Computer, Intel, LG, NVIDIA, Samsung, and Silicon Image Inc. The UDI specification was finalized in July 2006. The differences between UDI and HDMI was kept to a minimum since both specifications were designed for long-term compatibility.