Hitting the Ground Running: Pre-Integration Speeds System Development
If you look for an industry-ready box PC these days, many choices abound. There’s a product for every niche, it seems. The problem is: there seem to be more and more niches.
SUSANNE BORNSCHLEGL, MEN MICRO
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In transportation, technical requirements are growing in the areas of controls and graphics, for instance—places not typically associated with embedded computing requirements. What could be more natural than using a modular system concept to meet different computing needs, with much of the system architecture already predefined and tested?
The box computer concept is a perfect example of Aristotle’s famous quote that the whole is greater than the sum of its parts. The internal boards, components and software are not viewed as individual items that will provide a function for the system, but rather as one unified structure that can be quickly, easily and efficiently implemented into a larger computing system. From a design perspective, this eliminates a great deal of frustration and time to get a complex architecture up and running.
In recent years, embedded electronics have entered the stage of mobile applications. Especially in public transport, requirements keep rising. More and larger screens keep passengers informed and make electronics more in need of graphics than ever. In the background, a computer is typically connected to the actual vehicle functions and can fulfill additional tasks.
Whether it be the control end accessed by the operator, or the visual end facing the customer or user, these systems need to work reliably. Having a full unit not only built to an application’s specific requirements, but also knowing that this unit will perform as needed pretty much out of the box, gives many design engineers comfort. This is, no doubt, contributing to the growing concepts and usage of pre-integrated systems (Figure 1).
Pre-integrated systems feature modular electronics on the inside, in a ready-to-go configuration.
One factor driving the ability to pack more functions into one complete system is the continuing fusion of processing chips. One example is AMD’s Accelerated Processing Units (APUs). In addition to the actual x86 CPU, the chip also includes a GPU (Graphics Processing Unit) from AMD’s Radeon range with the performance level of a dedicated graphics card. This has allowed AMD to reduce the 3-chip solution consisting of a processor, Northbridge and Southbridge, which was common up to now, to a small-footprint 2-chip solution.
This example of reducing a component’s footprint has enabled more electronics to be contained within one system, contributing to advancements in the pre-integrated system approach, especially for embedded applications that absolutely require small form factors. More computing means more heat, typically, so chip manufacturers are also focusing on power reduction. The AMD 1.0 GHz dual-core G-T40R with integrated Radeon HD 6250 graphics, for example, has a maximum TDP (Thermal Design Power) of just 5.5 watts.
The Necessity of Continued Operation
Because the components and functionality of these box computers are contained within a sealed housing, the unit needs to perform reliably in not only rugged, and typically mobile, environments, but also over long periods of time. These pre-integrated systems are designed to be put in place and operate effectively. The time and effort spent getting the system up and running is of no use if it constantly needs maintenance. That said, there are varying conditions these units need to accommodate, as can be seen in the requirements of a mass transit bus manufacturer, for example.
These types of companies need to take a more global view than ones building systems for a factory—where the environment will remain relatively the same once identified, without the variable of weather, dust or corrosive elements. The demand for computers on board a bus in the midday heat of Dubai is vastly different than those required on a cool, rainy day in Britain.
Buses in a desert country are air-conditioned, of course, but the hot air flowing in from the outside at every stop is a strain on their internal electronics, especially if a device is installed directly above the driver’s seat. In this case, the computer can take over a number of jobs, such as registering a stop request or coordinating the display of stops according to the vehicle’s position. In addition, the device can reliably transmit passenger information or commercials to several independent displays—even in full HD resolution. It is the reduced complexity on the designer’s part to get the system implemented as well as the overall, built-in reliability of a pre-integrated system that enables this flexible operation.
Integration from the Board to the Box
Heat is forever a main cause of system failure. In many pre-integrated computer configurations, the actual design of the box itself is part of the overall thermal management. Fans, which consume additional power and are unreliable, must be serviced in regular intervals, so for a system designed to be put in place and run, there’s not a strong case for including them.
More sophisticated cooling concepts are employed in pre-integrated systems, especially with the amount of electronics typically housed within. This starts with the design of the main board—which can employ thermally conductive materials selected to spread the heat away from the critical spots—down to the walls of the enclosure itself. With this level of integration implemented early on in the design process, particularly hot elements, like the APU, can be positioned to have a direct connection to the housing using thermal grease.
Cooling fins on the housing itself can work as an additional heat sink for the entire system, enabling standard operation up to +70°C, or even up to +85°C with a small extension to the sides, which even exceeds the requirements of EN 50155 temperature class Tx. Some pre-integrated systems have been constructed in a way that enables the housing to handle up to 25 watts of power dissipation without a fan (Figure 2).
In addition to internal thermal management techniques, the flat sides of the enclosure can be utilized as heat sinks.
Pre-Integration Increases System Flexibility
With the necessary precision of these pre-integrated systems, it might seem that a drawback of this design would be inflexibility in system assembly, but the actual outcome is design flexibility in terms of I/O, data storage and even the enclosure itself.
I/O can include DisplayPorts, Gigabit Ethernet ports, HD audio and USB 2.0 or even accommodations for PCI Express Mini Cards, which opens up access to wireless communication protocols such as WLAN, UMTS or GSM.
If an FPGA is included in the design, UARTs, IBIS and CAN bus are other options that can be easily implemented within the system. A computer can even be configured to position itself via GPS or function as a Wi-Fi hot spot.
Because of the inherent shock and vibration of many mobile environments, movable parts tend to be notable points of system failure. Depending on the actual environment and needed configurations, storage options from a typical SATA hard disk to the more rugged mSATA slot or an SD card can be used for mass storage requirements.
Even the shape of the enclosure can be varied depending on the needs. One of the first customized versions has about double the width of the standard model to allow for a multitude of additional interfaces directly at the front panel. With the numerous options and levels of configuration, you can reduce costs by configuring the box PC for exactly the job that it is to do.
These can be used to control different vehicle functions, and special enclosure models can meet more specific environmental demands, such as protection from splashing water (IP67). When implemented a in mass transit application, these box and display computers can utilize railway-compliant networks and phone connections for wireless communication—in addition to the usual computer interfaces—to transfer service data to the control center or to receive traffic information.