What is DisplayPort?


DatumThursday, 31. October 2019 KategorieKnow How

Digital data transfer has been further developed: The DisplayPort is a standard for many Mini-PCs and monitors and ensures a resolution of up to 8K @ 60 Hz. What stands behind this digital multimedia interface and what benefits it has, will be explained in this article.

The DisplayPort was standardized by the Video Electronics Standards Association (or for short: VESA). The interface is a licence-free standard for the digital transmission of digital image and sound signals. The specification includes the transmission technique and the appropriate connectors and cables, as well as a guide line for adapters to HDMI and DVI. The reason for the development of DisplayPort was to create a digital interface for higher resolutions and like this, replace the predecessors VGA and DVI. 

Applications of DisplayPort

Since the DisplayPort takes up a lot less space than VGA and DVI, it is perfect for the use in notebooks and also our Mini-PCs. In contrast to the HDMI port, which is mostly used in TV or multimedia devices, the DisplayPort finds its place in the information technology, such as PCs, tablets or monitors.

Data transmission and pin layout of DisplayPort

DisplayPort works pretty similar to PCIe: It is a serial, scalable point-to-point-connection that can adapt the features of the transmission channel. When connecting a graphics card with a monitor, they synchronize and adjust the signal level between 200 and 600 mV.  

DisplayPort has 4 channels available, however, an image signal can be transmitted on only one channel, because each pixel is transferred one after another. DisplayPort also has an additional AUX channel, which on one hand holds the Display Data Channel (DDC) for the transfer of display data, and on the other hand a band width of almost 100 Mbit/s, with which webcams or microphones can be supplied, too.  

Both cable ends of the DisplayPort have the same plug. Like this, each end fits into the graphics card, as well as into the display. A list of the pin layout can be seen here.

Advantages of DisplayPort: Up to 8K resolution

In terms of image resolution DisplayPort has a lot more to offer than its predecessors VGA and DVI, because they only provide 1K respectively 2K resolution. Depending on the version of the DisplayPort a resolution of up to 1K (DisplayPort 1.1), 4K (DisplayPort 1.2), 5K (DisplayPort 1.3) and with the latest specification DisplayPort 1.4 even 8K is possible.

But the interface has some more benefits: First, as already mentioned, DisplayPort is a license free standard. Like this, manufacturers of small series don’t have to pay charges. DisplayPort also has a smaller connector that is not screwable but has a mechanical lock. This safes space and the interface can also be used on small devices.

The progression to DisplayPort 1.4

  • DP 1.1 (2007): The first final version has a maximum transfer rate of 8.64 Gb /s, which is sufficient for HDTV and bigger displays. DP 1.1 is copy-protected with HDCP 1.3 and introduces the feature DP++.
  • DP 1.2 (2009): The most significant change is the increase of the maximum data rate to 17.28 Gb/s. Another innovation is the support of MST (Multi Stream Transport), with which many monitors can be connected using one connector via the Daisy Chain concept.
  • DP 1.3 (2014): The data rate was increased again and now amounts to 25.92 GB/s. Thanks to MST, several 4K UHD- or WQXGA-displays can be connected.
  • DP 1.4 (2016): This version doesn’t contain an augmentation of the data rate, but the introduction and updates of some features: Display Stream Compression 1.2, with which the viewer should not recognize visual differences between compressed and not compressed images, the forward error correction, that reduces transmission errors, and the extension of the audio channels to 32.

Next to the normal developments from DisplayPort 1.1 to 1.4, over the years three special DisplayPorts were developed: Mini DisplayPort, MyDisplayPort and eDP. More information about those can be found here. 

DisplayPort at KUMO IV

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