Something old, something new: Marrying and migrating multimedia interfaces
As display interfaces transition to DisplayPort the embedded system design mantra is "in with the old, in with the new," ensuring a smooth switch from LVDS and VGA-based technologies.
PCs and mobile computers are rapidly migrating away from traditional LVDS or VGA display interfaces toward newer technologies like DisplayPort. Top players such as Intel and AMD are expected to stop supporting LVDS in the next 3-5 years, making migration to DisplayPort a necessity. Designers must determine how this new display interface fits into new and existing designs while preserving key requirements for embedded systems.
DisplayPort offers several advantages for the embedded market, starting with a clear cost benefit. DisplayPort is a royalty-free, open-standard digital display interface managed by the Video Electronics Standards Association (VESA). For embedded system designs that often involve long and complex Bills Of Materials (BOMs), DisplayPort offers huge cost savings over other standards such as HDMI. According to, the annual fee for adopters is $10,000, and royalty fees include 15 cents per end user-licensed product sold. While these fees make sense for commercial volumes, OEMs are often at a loss for how to offer HDMI for smaller-scale embedded designs while still making profits against the annual license fees and royalties.
At the core of embedded system designs are the trade-offs made between power and performance. Embedded applications require low power consumption coupled with optimized performance from single or multicore CPUs. For example, in fields such as biometrics or portable medical devices, OEMs need multicore processing that can support heavy high-resolution visualization and data processing. At the same time, they need a device that can run on batteries for several hours using an embedded module with power consumption below 10 W. DisplayPort was developed to directly address the need for low power, allowing CPUs to drastically reduce total power consumption through a much simpler and efficient layout.
With DisplayPort, a single cable manages several displays, which is an essential requirement in industries such as digital signage where multiple sleek flat-panel displays need to be interlinked and managed through a single controller. Minimizing cabling translates to more flexibility in configurations as well as less maintenance. The simple design also means reduced electromagnetic emissions and improved overall signal integrity, especially over much longer cable lengths than are allowed with LVDS. Whereas LVDS is ideal for applications with shorter cable lengths of up to about 10 meters, DisplayPort can support much longer lengths.
Simplifying multiple display support is certainly an advantage in the embedded market. For example, imagine an embedded device running the displays on the seat backs in an airplane. With DisplayPort, multiple screens can be daisy-chained together and run independent content simultaneously, all without cumbersome additional cabling or central processing complexity. Figure 1 shows examples of different possible display setups with a single DisplayPort connection.
HD resolution is critical for all areas of embedded systems, as today’s end users demand more visualization and high-quality human-to-machine interactions and end user experiences. DislayPort can preserve HD graphical resolutions at longer lengths. For example, WQXGA resolutions (2560 x 1600 pixels) are supported at a minimum of 2 meters. Full HD is easily supported at 15 meters. DisplayPort clearly has advantages even over DVI, as demand for higher and higher resolutions in digital displays increases and at some point DVI hits its limitations. By going beyond full HD and enabling fast refresh rates, DisplayPort will help OEMs keep up with future technologies.
Gradual transition to DisplayPort
For now, OEMs can continue using LVDS, VGA, and DVI while keeping DisplayPort on their future technology roadmap. DisplayPort offers backward compatibility with these legacy technologies, which have not been updated or active for several years. In addition, VESA has stated that DisplayPort is not looking to replace HDMI, but rather serves as an alternative for embedded developers.
The ideal embedded system today offers support for both options, allowing developers to leverage new and proven technologies to help speed development. Processors like the Intel Atom N2000 series and embedded boards like Eurotech’s Catalyst CV play a role in the migration story by supporting not only traditional interfaces such as LVDS and VGA, but also DisplayPort and Embedded DisplayPort. Supporting both display options gives developers an easy migration path that uses the same board package to extend product life cycles and doesn’t necessarily involve reengineering a design down the line. DisplayPort shows potential to be a big boon for the embedded market, reducing the number of standards and interfaces to just one that is actively updated and designed for longevity.
Eurotech’s Catalyst platform, based on the Intel Atom roadmap, is designed for technology migration and flexibility. The Catalyst CV (Figure 2) is available in a 67 mm x 100 mm form factor, and is optimized for the processor and performance rather than for a standardized form factor. This means that the module brings out all of the capabilities of the Intel Atom N2x00, including the multimedia features such as LVDS, VGA, DVI, HDMI, DisplayPort, and EDP.
The Catalyst CV also offers Eurotech’s Everyware Software Framework and Everyware Device Cloud, software programs that help simplify development and manage data through easy-to-use cloud services.
Flexibility to support new and legacy interfaces
The embedded market is an evolving industry that poses the unique challenge of supporting both new and legacy technologies to maintain the balance between performance and product longevity. While many new designs will incorporate DisplayPort, OEMs still need to support LVDS- and VGA-based products. Embedded systems that offer the flexibility of forward and backward compatibility will be critical in making this transition a smooth one.
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