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SMALL FORM FACTOR FORUM

May 2010

LAN’s End is Just the Tip of the Iceberg

COLIN MCCRACKEN & PAUL ROSENFELD

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Device manufacturers and OEMs have been “trained” that processor and chipset vendors determine the life cycle of single board computers (SBCs) and computer-on-modules (COMs)—typically 5 to 7 years. However, there’s more to SBCs and COMs than meets the eye, meaning that EOL of any other active component can wreak the same havoc on your product line as the EOL of processors and chipsets. Clock generators, super I/O chips, Ethernet controllers, switchers, regulators and embedded controllers for power rail sequencing are all lurking behind the scenes. And an end of life notice for any of these ICs can bring your SBC or COM board to EOL just as rapidly as the EOL of a processor or chipset. While some SBC vendors have been known to stockpile low-cost ICs without notifying customers of end of life, this puts you at the mercy of their forecasting accuracy.

Right now, certain LAN controllers are testing the will of embedded suppliers and customers. The PCI-based 10/100 Ethernet controller has become entrenched throughout the entire embedded market as stand-alone systems have given way to connected ones. These controllers are well supported in all major operating systems with all major RISC and CISC architectures. Alas, thanks to desktop market churn, all good ICs must come to an end. High-volume desktop markets have already moved to PCI Express x1 Gigabit Ethernet controllers, while server blades are all the way to the 10Gig realm.

It’s the end of the ubiquitous PCI LAN controller as we know it. Intel is well into its 12-month EOL / last-time buy period for all of its PCI 10/100 controllers. This paves the way for VIA, Realtek, Davicom and National controllers to follow suit unless any of these chip vendors have thoughts about grabbing market share by extending the life of their chips. 

Besides the many board designs that will be affected, many off-the-shelf small form factor (SFF) boards are quite exposed to this EOL as well. Specifically impacted are ETX and active backplane SBCs (EBX, EPIC and PC/104-Plus form factors), primarily those using Pentium M, Celeron M and even Geode platforms. Most board suppliers are coming clean about how long production could last, since the last-time order date for the popular 82551 MAC+PHY and 82562 PHY chips is upon us. 

Many ETX manufacturers have switched over to designing COM Express, CoreExpress, or Qseven modules exclusively by now, so good luck finding a drop-in ETX replacement with a non-EOL 10/100 PCI Ethernet controller. Unfortunately, GigE requires two more differential pair signals, which were never part of the ETX interface definition and hence cannot be easily adopted into an ETX solution. The four ETX reserved pins are spread out all over the place, unsuitable for design rules that require signal pairs to be routed closely together. While a few opportunistic module vendors may change LAN vendors to save system OEMs from a horrific baseboard redesign fate, they only delay the inevitable.

Stackable architectures are impacted in a much more dramatic way. It’s not just a matter of replacing one module with another as in the ETX case. Affected 10/100 LAN cards use the PCI bus on a 3.6” x 3.8” (PC/104 or ISM form factor) card. But replacement Gigabit cards require a PCI Express bus. Thus the SBC baby must get thrown out with the LAN bath water. And this can lead to a disaster as support for your ISA-based I/O cards could disappear as well unless you can find an SBC that provides both PCI Express AND legacy PC/104 ISA support up the stack.

At least the LAN controller issue won’t be repeated.  In many cases, the LAN controller is now integrated into the chipset. Hence, new Atom- and Nano-based SBCs come with PCIe GigE on board as if part of a re-emergence SBC comeback world tour. In addition, legacy-free COM Express modules and Mini-ITX SBCs also build the LAN controller into the basic feature set. Some new SBCs blend PCIe GigE with legacy-friendly ISA stacking. From the device driver point of view, PCIe is a transparent change from PCI. But in regulated markets such as avionics and medical, a change is a change, and the driver for the new LAN controller must be installed and a new OS image generated and re-qualified. After placing your last-time buy, update your design and drop us a line at sf3@rtcgroup.com.