One of the challenges with display technology is the huge increase in bandwidth that has occurred since LCD panels took over from Cathode Ray Tubes. Low end laptops have a million pixels, UHD (“4K”) displays
have 8 million and the latest Full Ultra HD (“8k”) displays have over 33 million pixels. Updating all those pixels takes a lot of bandwidth – to update a 4k display at 60 Hz refresh rates takes close to a gigabyte per second. 8 billion bits – that is a lot of bits! That’s why VGA ports and even DVI ports are starting to vanish in favor of standards like HDMI and DisplayPort.
The current release of HDMI is 2.0, and is tightly licensed with NDAs and licensing fees. VESA, who created the DisplayPort standard, states the standard is royalty-free to implement, but since January 2010, all new DisplayPort related standards issued by VESA are no longer available to non-members.
So after receiving a new Digilent Nexys Video FPGA development board, Hackaday regular [Hamster] purchased a UHD monitor, scoured the internet for an old DisplayPort 1.1 standard, and started hacking.
A couple of months and 10,000 lines of VHDL code later what may be the first working Open Source DisplayPort
implementation is available. The design includes a 16-bit scrambler, an 8b/10b encoder, and multichannel support.
We had noticed that [Eli Billauer] had done something similar, but as far as we know his source is unreleased (although he has some interesting notes about what he found). Although [Hamster] is the first to admit that it is not yet production ready, this forms a base for the others who will no doubt follow. Nothing makes life easier than a reference implementation to compare against!
The video below is a talk about DisplayPort 1.3 from [CraigWiley] who is on the VESA standards committee and includes a good overview of the technical details at a high level. If you are looking for other Displayport hacks, you can drive an external display from an iPad or even drive a Retina display from any Displayport output.
[DisplayPort Plug Image by Belkin CC-BY-SA]