Starting a new lifecycle for ETX/XTX applications

5 min read

The first generations of Intel's popular Atom processors have now been discontinued. For ETX/XTX-based designs, congatec modules with the AMD Embedded G-Series APU step in as perfect successors offering all the required features. Hence, a new lifecycle for these legacy systems and consequently an increase in the ROI of OEMs' applications is possible.

Introduced in 2000, ETX modules (for ISA and PCI) and the compatible XTX variants (for PCI and PCIe) constituted a new category of standardised board level products for x86 technologies: the extremely successful Computer-on-Modules. Engineers were convinced by the advantages they offered i.e. an integrated, already developed and tested COTS computing core and system customisation by using easily developed carrier boards. ETX/ XTX consequently became the de-facto standard and these modules still are the preferred platforms even for numerous recent system designs. If we just take a look at ETX/XTX shipments from 2010 to 2013, they totalled an impressive figure of 2.34 million pieces. This is 60 % more than their direct successor specification (COM Express basic) achieved in the same time frame. And it was not until 2013, that COM Express shipments reached the same numbers as ETX/XTX modules. This underlines the fact that established form factors remain very stable, even if their successors have been in place for several years.
(Source: IHS Inc. Standalone Boards, Computer on Modules and PICMG 1.x - World 2013)

Provide state-of-the-art user experience

Moreover, it can be expected that ETX/XTX modules will be used for many years more, as long as the base technology is still available and if the devices still satisfy end customers' expectations. Meeting and maintaining customers' expectations is, however, an easy task with Computer-on-Modules, as COMs-equipped applications offer high investment security and long-term availability even across several processor generations. And OEMs can always reap the benefits of latest performance gains by simply exchanging the module.

The only precondition for this is that the base technology still has to be available. For ETX/XTX-based legacy applications requiring full PCI and ISA support, the recent EOL announcement of the first Generation Intel Atom processors therefore calls out for a successor. Any products featuring Intel Atom N270 processors with Intel 945 chipset, Intel Atom processors D420 and D525 with 3100 SCH or Intel Atom Z Series processors with US15W chipset are affected. But what is the right choice now?

No need for a new design

If a major re-design of the application is currently not being planned, OEMs will want to continue using their already proven system design, as this is the simplest, fastest and most cost-efficient way. However, although the x86 world covers the full scope of software backwards capabilities even down to the 8086 processors, many new processor developments lack the necessary PCI and ISA support - a problem for any deployments requiring these buses. Since PCI and ISA are a fundamental part of the ETX and XTX specifications these designs are the ones most affected – not forgetting COM Express modules with pin-out Type 2, which also execute PCI. OEMs using these very widely deployed module specifications are looking for a fully compatible successor module and in doing so avoid a costly re-design of their applications. A platform is required that offers the fully compatible interface support, including full ISA compatibility. Furthermore, this new platform has to stay within the same thermal envelope and ideally also provide some headroom for additional computing and graphics capabilities to enable an improved user experience.

The Intel Atom successor: AMD Embedded G-Series

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ETX/XTX as well as COM Express Type 2 platforms fulfilling all these demands are indeed already available. They come equipped with AMD Embedded G-Series APUs and the Embedded Controller Hub A55. Plus, they offer full PCI support which enables embedded board vendors such as congatec to even implement full ISA bus hard and software compatibility – including fully compatible DMA support. These AMD Embedded G-Series APUs are available in 10 different power and performance combinations from 4.5 to 18W TDP. So developers can find the right platform even within the same thermal envelope that previous modules provided. This means that the new modules can be deployed without the need to change the cooling solution.

Increase the performance of existing applications

The AMD Embedded G-Series is, however, far more than just a substitute. For example, within the same power envelope, the graphics performance is much more convincing compared to the obsolete solution. Benchmarks, using the common 3DMark 06 show that the AMD Embedded G-Series APUs provide a 10 to 17 times higher average benchmark score than an Intel Atom D510 processor with the integrated graphics Intel GMA 3150. Moreover, all AMD Embedded G-Series variants with integrated AMD Radeon Graphics support two independent displays out of the box. This enables OEMs to increase the graphics capabilities of their applications and fulfil even latest demands for an immersive user experience, which helps to extend the new lifecycles of their applications even more. The result is increased customer satisfaction and ROI.

With eight different ETX/XTX modules

The congatec ETX module conga-EAF and the XTX module conga-XAF are an excellent choice. Both modules utilise the AMD Embedded G-series APU platform and the embedded controller hub A55E. They are available with single core processors running at 1.2 or 1.5GHz, or with dual-core processors running at 1.0, 1.4 or 1.6GHz and a thermal power dissipation of between nine and 18W. By default, the modules support four PCI bus masters (Rev2.3 compliant 33MHz), six USB 2.0 ports, two SATA II ports, two IDE channels (master/slave, up to ATA 133), a 10/100 Ethernet interface and an HDA audio port with analogue support (line in/out and microphone) via ALC262. The modules have ACPI-compliant power management and support Suspend to RAM (S3). Common embedded controller features such as I²C, watchdog, backlight and power dissipation are supported as well as the Trusted Platform Module (Rev1.2) for safety-critical applications. The discrete level graphics for two independent displays supports VGA (VESA compliant, up to 2560 x1600), LVDS (single/dual channel 18/24bit), DisplayPort and HDMI//DVI.

Migration services

congatec not only develops and delivers these ETX and XTX standard modules. The company also supports engineers in the drop-in replacement phase, where, for example, a migration of ISA-based applications and their crucial legacy drivers is required. This helps customers to optimise migration costs right from the start. As congatec is an AMD Embedded Solution Partner that has already executed several migrations from Intel to AMD technology, they have great expertise with migration challenges and can consequently consult engineers very effectively.

ISA support – a not so easy task

Although current processors and chipsets still are ISA software-compatible to support legacy operating systems such as MS DOS, they no longer deliver the required preconditions to support ISA expansion boards out of the box. With typical low-pin busses like LPC and SPI being incapable of providing full ISA hardware support, congatec leveraged the AMD Embedded G-Series APU with the A55E platform controller hub to provide full ISA compatibility. In particular, the possibility to map the ISA memory area to the PCI bus, enabled congatec to use a PCI to ISA bridge that provides full control of the memory so that hardware-compatible ISA support is provided on its conga-EAF. Implementing a suitable PCI to ISA bridge though is just the first step in this process, which requires not only a high level of in-depth hardware knowledge, but also a lot of software expertise to enable DMA control. Furthermore allocatable interrupts are required within the range of IRQ 0 to IRQ 15 to initiate actions in the user space. Moreover, ISA compatible I/O ports and the typical ISA memory (from C8000h to DFFFFh ), which is used by the ISA peripheral to provide application data to the CPU, have to be accessible for full compatibility. Last but not least, definable DMA also has to be enabled, so that ISA peripherals can write data directly into the system memory.

Processor/Chipset combinations which no longer support a native PCI bus can generate the PCI bus utilising a PCI Express to PCI bridge. This adds some latency to the PCI bus but is quite acceptable for most applications. Using this generated PCI bus with an additional PCI to ISA bridge adds again latency to the generated ISA bus. Most existing ISA bus applications run into problems with this significant latency.