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Hubert Hafner, Product Marketing Manager at Kontron AG explores how the new Pico-ITX Motherboard and new Computer-on-Modules based on ARM System-on-Chips are offering more efficiency for ARM-based designs
To date, ARM-based applications have typically been associated with application-specific development and full custom designs. However, the extreme diversification of different SoCs makes efficient design-in and re-use of ARM technology a nearly impossible task.
Standardised COTS components on board- and Computer-on-Modules-level can drastically minimise the ‘realisation potential’ for embedded applications. In order to meet current market demands regarding time-to-market and to minimise development costs, COTS components such as Pico-ITX motherboards are available.
In addition to this, the new ULP-COM Computer-on-Module specification for ultra low-power COMs is currently being ratified at the recently founded SGET consortium.
Ultra low-power ARM System-on-Chips (SoC) are common in current smart phones and support a variety of operating systems including Android.
In most cases, the ARM-based SoCs also offer long-term support that exceeds conventional availabilities of five to seven years. As a result, they are also very well suited for embedded systems.
Latest PC-style versions offer embedded applications extraordinary performance at very low-power consumption of typically less than 1watt.
In order to achieve these extremely low-power values, ARM-based SoCs are highly-specialised and complex designs, integrating many different I/Os and hardware sub-systems as required on the silicon.
ARM-based SoCs therefore do not provide a common generic range of interfaces in contrast to the x86-technology. They may use other interfaces for the same task compared to x86-processors and chipsets. Although this approach reduces the footprint on the one hand, it increases the complexity of the design-in, because attention needs to be paid to the specific setup of the sub systems and its own hardware and software design.
Therefore OEMs up until now had to build full custom designs or use proprietary building blocks and individual software implementations/ adaptations, as drivers for the same physical I/O often vary on ARM-based SoC level making new software compilations necessary.
In order to enable much more cost- and time-efficient application developments based on ARM technology, OEMs require commercial off-the-shelf (COTS) building blocks that already integrate core components such as SoCs, controllers and memory.
At the same time they should offer the flexibility to execute the different sub systems for interfaces that latest ARM SoCs provide.
Computer-on-Modules can feature exactly this combination of pre-integrated components combined with high -flexibility in regards to the application-specific integration of application-ready interfaces. Ideally, these modules should be based on a vendor-independent standard, in order to provide high-design security and efficient re-use.
Are existing module specifications a perfect choice?
Some module manufacturers offer ARM processor designs, for example on a Qseven basis. This however means that, the specification has to be opened up to facilitate the design and this can have disadvantageous effects.
If any type of modification is allowed, increasingly less positive scaling effects from the conformity of a standard can be achieved. This might not disturb the customer who needs to migrate. However, in the longrun, new business is of the utmost importance, and for this, a purebred specification presents the better alternative.
The clean cut from ETX to COM Express underlines this. Intermediate and temporary solutions are significantly less successful in the longrun. So, there is a lot to be said for the development of a new standard.
Additionally, a vendor-independent standard aids the establishment of a broad community of hardware vendors and service providers, which will further help in minimising the development efforts for new applications.
Standarised Group for Embedded Technologies
With the upcoming specification for ultra low-power Computer-on-Modules, under the working title ‘ULP-COM’, such a standard will become available in the near future. The release candidate of the specification is planned to be hosted by the Standardisation Group for Embedded Technologies (SGET).
As previously mentioned, the interface range of ARM and SoC processors is highly dependent on the individual ARM-SoC and differs from that of classical x86 platforms. For the targeted usage models, the ideal connector technology has to provide sufficient pins to interface the multitude of dedicated I/Os, offer a low installation height for slim designs and should be a cost-efficient solution.
Instead of adapting existing designs from already established Computer-on-Module standards such as COM Express or Qseven, the upcoming standard for ultra low-power COMs is completely new.
The reasons for this are best compared with the alternatives: With up to 440 pins the COM Express connector is an excellent solution even for the most complex designs. It also allows the highest quality layouts with many PCB layers.
Designs with card-edge connectors do not support many layers, due to the fact that, the height of the gold finger defines the thickness of the PCB. But ultra low-power ARM applications do not need many layers.
With slimmer card-edge connectors used for Qseven, which are usually based on the legacy connector of the MXM 2.0 standard, only provide 230 pins and simply cannot execute all demanded interfaces. Therefore for the ULP-COM standard, the 314-pin MXM 3.0 connector was chosen. With a connector height of just 4.3mm, it is particularly well suited to flat designs with a board-to-board distance of 1.5mm.
The connector is also available in a shock and vibration-resistant version for applications such as automotive. As the module uses a card-edge connector, a dedicated connector is only required on the carrierboard, minimising the bill of material.
To enable developers to obtain the greatest possible flexibility in terms of diverse mechanical requirements from the outset, two different module sizes are available: A short module measuring 82mm by 50mm and a full-sized version at 82mm by 80mm. The latter is not only intended for future high-performance multicore processors, but also offers more space to implement additional memory options such as NAND flash.
Additionally, the ULP-COM standard will also cover all other mechanical parameters similar to other established module specifications. This includes mounting hole positions as well as all parameters for a very efficient cooling standard that implements screwed heat spreaders, that are most efficient in terms of ruggedisation as well as heat dissipation, for applications in extended temperature environments.
In contrast to the mechanical design specification, electrical interfaces between the COM and carrier board are also a key issue. As a result it is the dedicated interfaces that justify the need for an individual standard to cover ARM and SoC platforms. For example, in the case of mobile handheld devices, MultiMedia Cards (MMCs) are preferred, to save space, weight and valuable battery power.
If size is a decisive factor, common x86 expansions connected via PCIe can be replaced by SDIO, which are also part of the ULP-COM interface range.
Further device class-specific peripheral components such as Bluetooth and Zigbee, as well as gyroscope and GPS sensors, can be attached using the up to five I2C interface. Two Serial Peripheral Interfaces (SPI) are available for the connection of touchscreens, sensors, or to connect storage media. Audio signals are provided to the carrier board by means of I2S.
Two MIPI-conforming camera inputs enable video-based applications to be implemented without additional controller components. The option to implement up to two CAN bus interfaces for machine controls, or for connecting to a vehicle network is particularly interesting for the automation industry and in-vehicle solutions.
Despite this interface range’s focus on power-saving for handheld devices, the classical x86 interface remains intact. This includes SPDIF, up to three USB 2.0 ports, 10/100/1000 Ethernet and up to three PCI Express lanes.
Specification specifics
With regards to video interfaces, the specification defines a 24-bit RGB output and the popular single channel 18/24 bit LVDS for connecting the primary display. A secondary display can be connected, either via HDMI or DisplayPort. But not all of the 314 pins are yet assigned to dedicated interfaces.
The reserved pins can be USB 3.0, a display serial interface or other up coming technologies. With this, the specification provides built-in design security as it is open to adopting future technologies that are not yet developed.
But one of the driving questions is, which processors will be available on these upcoming modules? As the initiator of the ultra low-power COMs, Kontron is currently working to implement three different SoCs.
Modules based on the NVIDIA Tegra 3 provide massive computing and graphics power for graphics-oriented applications such as digital signage and media players running on Linux or Android 4.0.
Modules based on the Texas Instruments Sitara AM3874 ARM Cortex-A8 microprocessor (MPU) performing at up to 1GHz, at less than 2watts power dissipation provide a wide range of choices for integration onto industrial applications. In line with this, the company plans comprehensive support for Windows Embedded Compact 7 as well as VxWorks and QNX.
Furthermore, Kontron will implement all five members of Freescale’s 10-15 years longterm available and highly scalable i.MX6 processor family with singlecore to quadcore ARM Cortex-A9 technology.
By this, customers have an ideally scalable COM family to hand, which they can use to design a complete product family with different performance levels and features based on one module family.
These modules are an excellent platform for a multitude of new scalable multimedia applications in markets such as digital signage, automotive and POS/POI Kiosks.
Lending a helping ARM
To enable customers to begin using ARM technology immediately and most efficiently, even with different hardware sub-systems, embedded vendors are providing ARM-based modules in bundles with extensive custom design services.
This means OEM customers can have application-ready platforms already integrated at board – and system-levels as standard products or customised and made to order.
In addition to this, Kontron will be providing extensive services during software development, ranging from driver development to OS code modifications.
The company plans to provide a unified and complete software infrastructure to the modules in the pre-installed operating system. This ensures that developers can immediately begin their application development above the operating system level.
Application developers are able to benefit from efficient migrations, quick time-to-market and significantly reduced development costs, because they receive an ‘application ready platform,’ which, if required, is already certified and ready to go.
Kontron AG
