New Wave of COMs
ARM on COM Modules: Meeting the Needs of Mobile Devices
A new design of very small modules is in the works that will support ARM processors with a standard connector. This is driven by the ever-growing need for high performance with minimum power consumption.
TOM WILLIAMS, EDITOR-IN-CHIEF
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There is change on the way in the embedded systems arena and we are just beginning to see the outlines of what it might look like. It looks like ARM. At least two companies whose entire offerings of embedded small form factor modules have been x86 are adding support for the ARM architecture. Led by Kontron, which has been joined by Adlink and is working with several other yet unnamed companies, a new module standard is taking shape that will be based on the low-power, high-performance ARM processor and in the future is planned to be able to accommodate custom SoC designs. For the present, however, the two companies are aiming at rolling out modules supporting one or two ARM implementations. If this effort is successful, of course, more will follow.
One of the big issues faced in trying to adapt the ARM processors to a standard module, of course, is that ARM CPUs come in a wide variety of implementations, with a wide variety of pin-outs. On the one hand, this would mean having to select devices with a widely applicable set of external interfaces—even if they have different pin-outs and adapting them to a module board with a standard connector. And the assignment of all the external connector pins must remain absolutely constant across all modules. On the other hand, the ARM approach puts a huge amount of functionality onto the same die, making the addition of support and peripheral chips much less of an issue and greatly reducing the board space and the power needed for a module.
That is definitely reflected in the size of the proposed modules, the first of which will measure only 82 mm x 50 mm (3.23” x 1.97”). For future designs, a “full size” module is envisioned that will measure 82 mm x 80 mm (3.23” x 3.15”). Both modules will use the same 314-pin MXM 3.0 connector, which will be able to support traditional features such as 24-bit RGB, but also be future proof with the ability to support later standards such as HDMI, LVDS and Display Port. The total system power consumption of such designs is targeted to be on the order of 3 watts (Figure 1).
The basic form factors of what Kontron is calling the “Low Power Embedded Architecture Platform.”
The first question, of course, is why would such established x86 houses now be branching into support for ARM? Both companies emphasize that this is not a break from x86, but an expansion into new markets. It is also made possible by timely developments. Kontron’s VP of marketing, Norbert Hauser, notes that, “For the first time now you find the complete infrastructure in terms of operating systems, tools around ARM that make it very convenient—not the least with Android and Linux to work in this area.”
The overriding consideration, however, is power consumption. According to Hauser, more and more customers are asking for power consumption below 5 watts. We have seen how ARM has taken the lion’s share of designs in the smartphone and tablet arena and embedded vendors are now seeing similar demands for low power and mobility in the industrial sector for such things as ruggedized tablets, mobile equipment, test and measurement, etc. The main driving point is battery operation and low power consumption.
A parallel development that is making this possible is the rapidly growing market for ARM devices. Hauser notes that while the PC market is growing at about 3 percent, the ARM industry is growing at over 50 percent. The volume of the consumer market for mobile devices, tablets and smartphones is driving down the costs of the components associated with them. It is a parallel phenomenon to what has driven the embedded industry from the PC arena. The x86 itself, as well as technologies such as the ISA bus (ubiquitous in PC/104), PCI and USB, all came from the PC world into use by the embedded industry partly thanks to their wide acceptance and high volume (lower cost) production for the PC.
Now, according to Henk van Bremen, Adlink’s product director for Embedded, “It is happening today with the breakthrough of ARM and RISC in the intelligent mobile phone and tablet market that is taking the traditionally x86 dominated netbook market by storm. For the first time, embedded customers will have the same wide choice of operating systems on ARM as on x86, enabling efficient implementations of new and complementary embedded applications based on ultra-low-power devices that were not possible with x86 based platforms. Adlink will be able to offer a wide range of OS support, including Linux, Android, Windows CE, Windows 8, VxWorks and QNX.”
Both Kontron and Adlink emphasize that they are not aiming at the low end consumer devices, but at industrial applications and multimedia. At the time of this writing neither company is disclosing details about the specification nor announcing any products based on it. Both have, however, mentioned plans to offer modules based on Texas Instruments implementations of the ARM architecture based on its support of long life cycle management and extended temperature ranges, which are particularly important to industrial customers. Kontron has additionally indicated that it will be working with Nvidia because that company’s CPU family is very well suited to multimedia and high-end processing applications.
While Kontron has made no further indications of its plans with Nvidia, it is known that Nvidia’s Tegra2 series uses a dual-core ARM Cortex-A9 CPU. This implementation does not include ARM’s advance SIMD implementation named NEON but does integrate Nvidia’s own GPGU (different versions in different family members). In addition to advanced video and graphics processing, the Nvidia GPGU is capable of high-end number crunching and DSP operations. It also included an ARM7 processor to handle tasks with lower performance requirements and thus additional power savings (Figure 2).
The Nvidia Tegra series is an example of an ARM architecture with custom additional processing elements. (Source: Nvidia)
While no details about actual pin assignments are currently available, the new form factor will support the most common I/O functions, including SATA, PCI Express, USB 2.0, a number of different camera interfaces and others. It will not include as many USB channels as, say, COM Express, which supports six.
There appear to be some as yet unanswered questions as to how the new form factor will go forward. It is being presented as a “slim and low-profile solution for ARM/RISC and SoC ultra low power processors.” That would imply that it may one day also support architectures other than ARM and even custom SoC implementations. Obviously all the pins available on the modules have not been assigned and it would seem reasonable to assume that they will be assigned as more implementations offering additional or unique I/O are adopted. To date, however, no actual standards body has been established but both companies are aware that as customer acceptance grows and the need to support additional devices increases, there will have to be an organization that oversees the standard.
Then there is the matter of software support. The world of ARM is definitely different from that of the x86 where you have a BIOS and a board support package, which may include a selected operating system. At that point one can quickly start application development. With ARM, there is first of all no BIOS and so a hardware adaption layer (HAL) along with drivers and other matters must be solved. It requires more engineering and Kontron has established a Global Software Center to offer software services for a fee to get designers up and running and working on their applications.
Adlink’s CTO Stephen Huang indicated that there would be support for various operating systems including Android, Linux, VxWorks, QNX, Windows CE and Windows 8. If the vendor offers that level of off-the-shelf support, developers should be able to select their own tools and get started quickly. In fact, the availability of ARM and other RISC processors on a small, low-powered module coupled with hardware and I/O level software support will no doubt go a long way toward moving this architecture into a growing number of embedded applications that do not achieve the volume that has normally been needed to justify the development costs.
That volume, which is growing in the consumer arena, is making possible the adaptation of such technology in the lower-volume embedded space. The ability to offer an architecture such as ARM in a more ready-to-go package with software and support will speed its adoption into a growing number of designs whose hunger for performance and low power will only continue.
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