An Overview of Current Display Interfaces

7
DisplayPort
In late 2005, another consortium of computer and display electronics
manufacturers – HP, Dell, Philips, NVIDIA, ATI (now AMD), Samsung, and Genesis
Microchip – brought a new digital display interface specification to the Video
Electronics Standards Association (VESA) as a proposed new standard. About a
year later, VESA published the original DisplayPort standard. Since then, the
original group of promoters has expanded to include Intel and Lenovo, and the
spec was revised to the 1.1 version to better enable re-use of existing PCI-Express
designs, and to support the Intel HDCP content-protection system. The current
version of the specification is now DisplayPort 1.2.
DisplayPort uses a packetized communications protocol, which enables simple
support of multiple data types and other features. Audio may be transferred –
optionally – along with the digital video information, as well as other data types
(text, etc.). Later versions are expected to use the packetized protocol to enable
support for multiple displays per physical connection, tiling, conditional update,
etc., with full backward compatibility with the original spec.
DisplayPort was also designed to be both an external (monitor, TV, etc.) connection
as well as an internal (panel-level) interface, which will permit the development of
such products as direct-drive monitors. Physically, the connector resembles HDMI in
size, but differs in the shape of the shell and the thumb-operated latching
mechanism.
DisplayPort source and sink (display) devices may use one, two, or four “lanes”
(differential data pairs), depending on their data rate needs; the interface
automatically configures itself to make the best use of the available capacity. With
a full four lanes in use, DisplayPort 1.1 provides about 10.8 Gb/s. of raw capacity.
DisplayPort 1.2 released in 2010 doubled this capacity to 21.6 Gb/s while
maintaining backward compatibility with the earlier standard, as well as providing
support for increased functionality such as multiple audio and video streams (and
so support for multiple displays) over a single physical connection.
Figure 4. DisplayPort Connector
1
19
2
20
Table 4. DisplayPort Connector Pinout
Source
Pin
Sink
Pin
Signal
Source
Pin
Sink
Pin
Signal
1
12
Lane 0+
11
2
Ground
2
11
Ground
12
1
Lane 3-
3
10
Lane 0-
13
13
Ground
4
9
Lane 1+
14
14
Ground
5
8
Ground
15
15
AUX Ch. +
6
7
Lane 1-
16
16
Ground
7
6
Lane 2+
17
17
AUX Ch. -
8
5
Ground
18
18
HPD
9
4
Lane 2-
19
19
Return
10
3
Lane 3+
20
20
DP Power
Note: Cable assemblies do not carry DP power