Qseven - Computer-on-Module - Technology Overview

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The last couple of years Qseven has been seriously established, mostly in Europe, but recently also in Asia and USA. COM modules in that particular form factor are in use in a variety of products ranging from computers in buses, medical technology and HMIs. More and more embedded companies join the consortium behind the standard and offer their own Qseven modules.

The reason for the popularity of Qseven is a combination of compact size (70mm x 70mm) and low height, cost efficiency and access to contemporary and high-speed interfaces such as PCI Express, SATA, Gbit Ethernet and USB 3.0. Lately the number of options and possibilities has been increased from the release of a number Qseven modules based on powerful ARM processors and AMD G-series APUs. 
But let’s start at the beginning, the very beginning. About ten years ago X86 processors had grown in complexity to the point where one could question pursuing in-house development of hardware, even at large OEM customers with big production volumes. The use of readymade standardized computer boards (COTS, Computer-Off-The-Shelf) was an option to consider. The uniqueness of the products was often found in functionality and interfaces in hardware which were speaking against the COTS computer board option.

This situation was the breeding ground for the idea to use a readymade computer module mounted on a tailor-made carrier board. The computer module mainly contained the CPU, chipset and memory and was to be used in products from many companies. The hardware as a whole was made unique by adapting functionality and interfaces on the carrier board on which the module was mounted.

Driving forces behind Qseven

Since a computer module is used on numerous carrier boards, in a lot of products, from many companies standardization is needed. ETX and COM Express are a couple of standards which define properties of the module such as size, hole pattern and connectors for mounting the module on the carrier board, the minimum and maximum set of interfaces, pin-out, power consumption and cooling options.
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A couple of COM module form factors compared in size.

The specification of the standardized computer module, COM module (COM, Computer On Module) is of course to a large extent influenced and limited by existing processors and chipsets. It came as no surprise that the release of the low power processor Intel Atom in 2008 also lead to the introduction of yet another form factor with new properties. Intel Atom offered a decent performance level but most importantly really low power consumption and a compact size. This opened up for new application areas. X86 processors had made their way into handheld and battery powered embedded products.
The Qseven form factor was launched to meet the needs for a compact and cost-efficient module standard with new high-speed interfaces included. The MXM II connector was one of the keys to keeping costs down and still offers durability and quality. Qseven modules use an MXM connector to connect the module to the carrier board.

MXM connectors keep cost down

MXM connectors were originally used for connection of graphics modules in high-end notebook computers. The production volume was, and is, large. Only one actual MXM connector is required, the one on the carrier board. The Qseven module has gold-plated “fingers” printed directly on the board serving as the male connector to match the connector on the carrier board.

MXM connectors have proven reliable even in demanding environments including humidity, vibrations and temperature changes. MXM connectors are available specified for the demanding requirements in automotive applications. Qseven modules are in use in transportation and in unmanned vehicles. One example is Swedish train operator SJ who chose a Qseven module for an infotainment application in their trains. The train environment is typically considered to be a demanding environment for electronics. We’ll return to this example later on in the text. Let’s first have a closer look at the advantages that comes with compact size.
A Qseven module measures 70 mm x 70 mm. In spite of the limited surface for mounting components there is room for a full-blown X86 platform including up to eight DDRII/DDRIII memory circuits, Flash SSD and Ethernet controllers. The specified height of a Qseven module, heatspreader included, is no more than 14.2 mm. The compact size of Qseven turned out to be crucial in the following example based on experiences from one of Hectronic’s customers.

Avoiding complete system redesign

The existing product was based on a 3.5 inch single board computer connected to a couple of sub systems. Linux was used on, the elderly X86 processor, Intel Pentium III. Industrial cameras were connected using the Firewire communication interface.

The computer was no longer available on the market and a replacement was needed. Requirements put upon the replacing hardware were among other things that connectors were placed according to the predecessor and access to Firewire. The 3.5 inch SBCs on the market didn’t meet any of these requirements. And ever-present was the concern to avoid a costly redesign of the complete system including electronics and mechanics.

The alternative using a COM module on a carrier board seemed to be the better choice. The carrier board could easily be adapted to some of the requirements by using the 3.5 inch format and placing connectors and mounting holes in all the right places. It remained to be decided upon module form factor, a decision governed by the interfaces and controllers required.

Evaluating form factors

COM Express, ETX and Qseven were evaluated. ETX is nowadays a standard mostly used when access to legacy interfaces such as PCI or ISA bus is a necessity. This customer rather needed access to new and high-speed interfaces with a projected long life time, not the least to ensure future supply of Firewire controllers. PCI Express was one of the desirable interfaces, but that wasn’t (and isn’t) included in ETX modules. ETX modules weren’t small enough either.

Qseven and COM Express both offers PCI Express. The choice finally fell upon Qseven based on the more compact size and in particular the limited height. The Qseven module mounted on a custom made carrier board needed to fit the existing space and mechanically couple to the existing cooling solution. A Firewire controller was mounted on the carrier board and connected to PCI Express.
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The cost per unit for the solution was comparable with the price of the single board computer to be replaced. One of the reasons, of course, was that the MXM connector used is relatively cost-efficient. Hectronic’s Qseven module offered most of the functionality and interfaces needed. Thereby the carrier board could be uncomplicated and manufactured at a low cost. But first and foremost the cost in time and money from a complete redesign was avoided.

New functionality in the Qseven standard

The Qseven standard has been around a couple of years now. A lot of the Qseven modules on the market supports version 1.11 of the standard. In version 2.1, the latest, interfaces for control and communication such as SPI have been added. The SMBus and I2C were already included in the prior versions of the standard. CAN has been added in version 1.2 because of the interest shown from the automotive industry. CAN is included in the Qseven specification but is not commonly supported in X86 platforms. Such platforms need additional controllers to be integrated on the module for CAN access. Intel Atom E6xx with the EG20 chipset is one of the platforms with support for CAN.

It’s a common strategy to include support for legacy interfaces needed such as serial ports, PS2 and parallel ports on the carrier board. Super I/O controllers can be connected to the LPC bus (Low Pin Count bus which is more or less an 8-bit serial replacement for the ISA bus). The Qseven standard specifies a minimum configuration along with additional optional interfaces up to the maximum configuration according to the standard. SDIO and CAN are two optional interfaces not included in the minimum configuration.
PCI Express is mandatory. Four ports is the maximum and one port is the minimum. USB is obligatory, from four to eight ports. SATA isn’t a necessity but usually is included in the most recent modules. The standard implies none to two SATA ports. A less extensive minimum configuration for modules based on ARM processors was included in version 1.2. PCI Express was left out in this minimum configuration. The graphical interfaces LVDS, SDVO, DisplayPort and HDMI has been included in the first version of the standard. But it’s only recently that Qseven modules have been launched including processors also supporting DisplayPort and HDMI.

Qseven applied in mobile products and more

Qseven modules use single 5V DC power. The maximum TDP (Thermal Design Power) is 12 W, targeting handheld, mobile products or other passively cooled products in small and fanless enclosures. The maximum TDP in COM Express is 120W or 188W, depending on pin-out and the revision supported. Most of the COM Express modules consume 15W to 50W in practice. Qseven has turned out to have a wider usage than merely compact, mobile and battery powered products. Characteristic requirements in applications for which the choice have fallen upon Qseven are typically compact size, cost-efficiency, low power consumption and passive cooling.

One of Hectronic’s customers in medical technology has a product that serves as a good example. It’s neither battery powered nor mobile but the properties in Qseven still offers advantages. X86 performance is needed to monitor vital signs from sensor data and to present the information on a 14 inch touch display. Restrictions due to the IP classification of the product didn’t allow a fan and air openings in the enclosure. The system is based on Hectronic’s H6049 Qseven module based on Intel Atom Z510/Z530. Power consumption is low enough so that the heat can be distributed out over a large surface on the enclosure and thus keeps the temperature within the limits without a fan.

Handheld measuring instruments, industrial tablets and mobile medical equipment are among the expected application areas for Qseven. Less expected was perhaps that the form factor has had wide usage in areas like industrial automation, vehicle computers, medical HMIs and control systems for unmanned vehicles.

Qseven in rugged applications

Swedish train operator SJ uses the Hectronic H6049 Qseven module together with radio modules and FPGA in an infotainment system onboard the X55 trains. SJs objectives with introducing a new infotainment system were to lower the cost of maintenance required using the existing solution with connections at every seat and to generally create a more pleasant travelling experience.

The challenge involved giving the passengers access to FM radio onboard the train in an environment with windows and walls reducing radio signals with 60dB to 70db and the fact that the best quality radio transmitter frequency switches as the train travels at 200 km/h. Other challenges were to withstand vibration, humidity and electro-magnetical disturbance from sliding contacts on air cables and to meet the requirements from the EN 50155 standard for electronics in trains.
The development project balanced technical requirements and requirements to keep costs down through a combination of technical development and readymade components and modules, one of which was the Hectronic H6049 Qseven module.
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The system hardware is a semi-custom design including a carrier board with audio circuits and an FPGA, an FM Radio RTX Module developed by Generic and the Hectronic H6049 Qseven Module with Intel® Atom™.

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The system hardware is a semi-custom design including a carrier board with audio circuits and an FPGA, an FM Radio RTX Module developed by Generic and the Hectronic H6049 Qseven Module with Intel® Atom™.

The 12W maximum TDP of course limits the performance levels to be expected in Qseven modules. Hectronic released the H6071 Qseven module based on AMDs G-series of APUs. AMD uses the name APU (Accelerated Processing Unit) to emphasize the point in using a combination of a low power X86 CPU and an advanced GPU in the same circuit, actually on the same silicon die.

On-chip GPU increases Qseven graphics performance

The Radeon 8000 GPU is integrated with the CPU to offer the best possible 2D/3D and video acceleration. Another interesting option to make use of AMDs APU is general purpose GPU computing (GPGPU) by taking advantage of AMD’s Open CL support. One of the advantages from the GPU being integrated with CPU, in comparison with the use of a separate graphical processor, is that the limitation from the memory bus is avoided.

A Qseven module in this performance segment is well suited for applications such as advanced image processing, vision control systems and integrated digital signage solutions. Yet other areas of use that will benefit from the increased graphical performance are powerful radar and navigation systems at sea such as ECDIS (Electronic Chart Display and Information System).

The Hectronic H6071 is a COM module in the Qseven form factor based on the low power processors AMD Embedded G-series, single and dual X86 cores respectively and the Radeon 8000 GPU. The Qseven form factor makes H6071 a legacy free module with a full range of contemporary low voltage differential serial interfaces such as PCI Express, USB 3.0 and display interfaces such as DisplayPort, HDMI, DVI and Dual 24-bit LVDS. Qseven modules are defined for low cost and ruggedness, with an MXM type edgecard connector interfacing the carrier board. H6071 has soldered memory and optional on-board SSD.

Qseven and ARM

The complexity and performance in ARM processors have been closing in and reached the levels found in X86 platforms in the low-end segments. Software development is often a bigger challenge for ARM processors compared to X86. BSPs (Board Support Packages), which normally are offered along with the COM modules, come in handy to support software development with ARM. Difficulties in hardware development from high speed memory and interfaces are the same for ARM and X86. Early on, the complexity in X86 platforms triggered the evolution of the strategy to separate hardware in a COM module and a carrier board.

 

That’s why it’s no surprise that Qseven modules based on ARM processors such as Cortex A8 and dual core Cortex A9 in Nvidia Tegra 2 have been introduced on the embedded market. The iMX6 processors from Freescale have become popular on Qseven modules. These powerful ARM processors offer support for high-speed PC interfaces such as PCI Express, SATA and Gbit Ethernet. In practice Qseven is the first form factor that’s offering standardized modules based on ARM.

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