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Communication interfaces in the industrial environment are characterised by the capabilities of television and personal computer technologies from the consumer sector. Yet professional display systems, which must be equal to consumer television or video entertainment systems, must at the same time meet the much higher industrial requirements in terms of robustness and durability. This is true particularly for applications in automation technology and process visualisation, but even more so in the fields of digital signage and point of information (POI).

Today, high resolution full HD visualisation is standard and even higher resolutions such as 4K (four times the resolution of HD) lie just around the corner. Therefore, industrial solutions are needed that support the implementation of existing and future requirements in new projects.

In the past, it was often common that the resolution of the graphics integrated on the board was sufficient for driving the display systems, while additional external graphics cards were used for more demanding systems. However, through the fusing together of CPU and graphics unit into one chip and the ongoing miniaturisation from a three-chip to a single-chip solution, new products are coming on to the market that can now meet these more demanding requirements. The direction of development in this area is clearly defined; higher resolution and the capability to simultaneously drive multiple displays.

Faster images

The design cycle of human machine interface (HMI) systems can be optimised by the use of a high-performance processor module that integrates all standard PC functions. The Computer-On-Module (COM) format is easily mounted via a standard connector on a baseboard, on which all application-specific functions are implemented. The embedded modules, which come in standardised form factors, are available in different versions with a choice of processors. The established PCI Industrial Computer Manufacturers Group (PICMG) COM Express form factor is offered for high-end platforms.

Although two graphics interfaces (VGA and LVDS) were sufficient for the first COM Express modules, further digital interfaces were added in the latest revision of the specification. With the shift from Type 2 pin-out to Type 6 pin-out in the new COM Express profile, up to three digital display interfaces are supported in addition to fast USB 3.0. Digital display interfaces, especially DisplayPort (DP), have basically replaced analog interfaces. However, due to compatibility reasons, VGA has not yet been completely eliminated. An additional embedded DisplayPort (eDP), which can optionally also carry low-voltage differential signalling (LVDS), is provided for a device internal display.

DisplayPort (DP), specified by the Video Electronics Standards Association (VESA), is an interface for the transfer of audio and video signals between processor and display. Image data with a resolution of up to 4096 x 2160 pixels at a frame rate of 60 full frames per second can be transferred using DP. 3D applications with full HD images at 120Hz are also possible. The usable resolution is, for the most part, independent of the cable length. The maximum data rate of DisplayPort (DP) is 5.4Gbit/s.

Using the additional digital display interfaces, systems that can drive multiple independent displays from a single CPU module can be built. No external components such as an external graphics card are necessary for these solutions. This reduces costs and facilitates streamlined system integrations. At the same time, the long-term availability of the devices, which is especially still a problem for graphics cards, is improved.

Multiple displays

In principle, only three full HD monitors can be driven from the three DisplayPort (DP) interfaces. However, in many cases — for example, building a 2x2 video wall — it is better to be able to connect four independent HD displays together. Furthermore, multi-monitoring applications with four displays are rapidly gaining importance. For example, processes can be visualised on one screen, while camera images, status indicators or a Windows-application is displayed on the other screens. Alternatively, it is also possible to drive a 4K monitor with a resolution of 4096 x 2160 pixels.

Figure 1: The MSC C6C-A7, a COM Express Type 6 high-performance module family in compact form factor, is based on AMD’s Embedded R-Series Accelerated Processing Units (APUs)

A high-performance COM Express processor module (Figure 1) in compact form factor, based on AMD’s Embedded R-Series Accelerated Processing Unit (APU), can be used to drive the HD displays. The APU features very powerful graphics and high parallel computing performance with low power dissipation. Although only three DisplayPort (DP) outputs are available, four independent full HD displays can be driven — without an external graphics card. Several possibilities for the realisation are, in principle, available.

Thanks to the multi stream transport (MST) technology, a DisplayPort (DP) hub mounted on the carrier board or externally delivers two separate streams for the two monitors. Through onboard mounting of the MST hub, the system costs are obviously increased. The remaining two outputs (DP0 and DP1) continue to deliver DisplayPort (DP), High-Definition Multimedia Interface (HDMI) or Digital Visual Interface (DVI). A further variant is the use of a DisplayPort (DP) daisy chain compatible monitor. The display is connected to the DP2 output and also drives the fourth monitor.

The third solution is achieved without additional hardware or special monitors. Three DVI monitors are driven directly via the three digital ports. A fourth display uses part of the multi-functional PCI Express x16 signals (PEG) as DVI port (GFX connections in Figure 2). At least two of the displays must have the same resolution, otherwise the effort incurred for the special graphics driver will be too complex.

Figure 2: Block diagram of the MSC C6C-A7 CPU module with digital display interfaces

The latter cost-optimised solution is implemented in MSC Vertriebs GmbH’s high-performance MSC C6C-A7 COM Express module family, based on AMD’s Embedded R-Series Accelerated Processing Units (APUs) with quad-core or dual-core processors. By means of MPEG4-, MPEG2- or H.264-decoding, two full HD video streams can be decoded simultaneously. A video compression engine (VCE) accelerates the encoding of HD video streams and enables real-time transcoding. By mounting additional, external graphics cards for driving four or six monitors, up to ten displays can be driven with the Computer-On-Module (COM).

AMD Eyefinity technology is a solution developed by AMD that supports the drive of multiple displays using a single enabled AMD R‑Series APU. This technology is now available on a COM Express compact form factor. Eyefinity allows the connection of six independent display contents on just one graphics processing unit (GPU). Due to the simple configuration and flexible upgrade possibilities, the monitors can be used in various landscape and portrait modes. Thanks to the software, for example, the distortion that occurred with video walls caused by the monitor frames can simply be 'calculated out' and thereby compensated for.

For applications with vast amounts of data — for example, high resolution image acquisition — besides the CPU cores, the high-performance arithmetic units of the graphics controllers can be used for floating point, vector and image processing tasks. This is possible thanks to a uniform programming for various high-performance hardware architectures through the vendor-independent, non-proprietary programming platform Open Computing Language OpenCL.

OpenCL is an open and royalty-free programming standard maintained by the Khronos Group. The Khronos Group is focused on the creation of royalty-free open standards for parallel computing, graphics and dynamic media on a wide variety of platforms and devices. The OpenCL specification consists of the language specification as well as Application Programming Interfaces (APIs) for the platform layer and the runtime. The language used is based on a subset of ISO C99, which is a popular programming language among developers. Thanks to the hardware-independence and easy portability of OpenCL, companies can reuse their substantial investment in source code and thereby significantly optimise development time and time-to-market of modern, complex image processing systems. In order to use the advantages of OpenCL, COM Express processor modules with AMD’s Embedded R-Series APUs support this standard. Furthermore, appropriate starter kits and carrier boards are offered for early evaluation and for prototyping of COM Express module based systems.

The capability to drive four full HD displays is interesting in a wide range of applications such as process visualisation, medical technology for complex image processing and in monitoring systems, for example, flight control systems. Additional applications can be found in the fields of infotainment, point of sale (POS), point of information (POI) and kiosk systems, for example, in transportation and casino gaming applications with multiple distributed displays.