PICMG Picks Up Steam—All the Way to the Red Planet

PICMG President and Chairman Joe Pavlat describes PICMG evolutions from small to large, including COM Express, CompactPCI, AdvancedTCA and MicroTCA.


In the embedded space there are three primary open standards organizations: PC/104 Consortium, VITA and PICMG. Of the three, PICMG has perhaps had the most activity over the past twelve months since it’s so closely tied to the commercial market’s technology whims and endless product introductions. There have been updates to COM Express, CompactPCI, AdvancedTCA (it’s now officially ok to call it “ATCA”) and MicroTCA. An interview with PICMG’s president and chairman—and my personal friend—Joe Pavlat reveals the details going on in three major spec areas.

Going Back 20 Years
PICMG began in 1994 and continues to evolve with technology trends. In the last year alone, the IEEE has finished off the 40G Ethernet spec, Intel has refreshed the Atom product line to the Silvermont architecture and won SoC smartphone designs, Cisco now forecasts M2M node growth on the same charts as smartphones and tablets, the move to serial interfaces like PCIe Gen 2/3 continues unabated, USB 3.0 is commonplace, and board vendors keep introducing newer, faster, denser versions of AMD- , ARM-, Freescale- and Intel-based single board computers (SBCs). Hundreds of companies participate in PICMG to stay abreast of and exert some control over all this change.

Says Pavlat: “Our membership started to decline a bit after the 2008 financial collapse, but PICMG is still profitable and we’re picking up new members again.” Membership now stands at about 200 companies, with some of the biggest names in the tech world listed on the PICMG website (http://picmg.org/v2internal/membership.htm#memberlists). The organization focuses on three core technology areas, which the membership continues to develop (Table 1): the smallest form factor is COM Express; the middle size is CompactPCI and now CompactPCI Serial; and the largest is ATCA, MicroTCA, Advanced Mezzanine Card (AMC), or what PICMG calls collectively “xTCA.” Of all the tech trends, says Pavlat, the move to serial interfaces is providing the most change in PICMG’s specs.

Table 1: PICMG’s three core form factor categories.

COM Express Version 2.1
Pavlat believes COM Express is “probably the second most popular small form factor behind PC/104,” having dozens to hundreds of vendors offering COM Express versions. There are over 700 products listed on the PICMG Product Listings section of the website (http://members.picmg.org/kshowcase/view). When first created, COM Express took a much different tack from PC/104: it sought to abstract all of the nuances of high-speed signaling from the user. By putting the CPU and chipset on the mezzanine (computer-on-module) card, the end user “didn’t need to worry about high-speed interfaces, trace impedances, buried vias or any of those details,” says Pavlat. The COM vendor worried about that; all the user need to do was design the baseboard to interface to relays, serial lines or other system-level I/O.

Because COM Express users are not willing to pay for features they don’t need, the PICMG spec COM.0 defines seven different pin-out types. Type 1 and Type 10 modules have a single 220-pin connector (A-B), whereas Types 2 through 6 use a pair of 220 pin connectors (A-B, C-D) for a total of 440 pins. The details are shown in Table 2, taken from the COM.0 PICMG specification. For the sharp-eyed reader, Types 7-9 are reserved for the future. COM Express boards can also come in various sizes called Mini, Compact, Basic and Extended.

Table 2 also shows the market trend from parallel interfaces to serial ones, and PICMG felt the need to revise the COM Express specification COM.0 (1995) to Version 2.1 in May 2012. According to Pavlat: “There were about 15 companies actively participating in defining the serial interfaces and modifications to COM Express. Of note were ADLINK, Radisys, Kontron, Congatec, PFU Systems and GE Intelligent Platforms, though there were others.” The changes made to COM Express are too numerous to list here, but the design trend towards rich multimedia and high-res video interfaces played a strong role in the redesign. There’s now extensive video port support for VGA, LVDS, SDVO, DP, eDP, DVI and HDMI terminal drivers plus a x16 PCI Express Graphics (PEG) port to carrier board graphics controller.

Table 2: COM Express pin-out types. Type 1 is the least functional with the smallest amount of I/O. (Courtesy: PICMG COM.0 specification.)

The changes include: migrating AC97 audio to high-definition audio; the SDVO interface is no longer muxed with the PEG port but available now via a digital display interface port in Types 6 and 10; there are more PCIe lanes added throughout; rarely used 12V pins were “reclaimed” for new serial functions; IDE and PCI ports were dropped or diminished for PCIe and SATA; and LVDS ports were added, some of which share pins with optional CAN bus signals.

All in all, a comprehensive update of the original 1995 spec was performed to evolve COM Express with the changes in serial interfaces, IC vendor chipsets and end user requirements. It’s interesting to note what COM Express doesn’t do. According to PICMG’s Pavlat: “Unlike VME, which intentionally maintains backward compatibility because of its customer base requirements, it doesn’t always make sense for COM Express to be backward-compatible.” The market wants forward momentum, and PICMG is delivering it with major changes to the COM Express specification to Version 2.1.

As well, PICMG members are in the process of overhauling the “COM Express Carrier Design Guide,” a textbook-like document describing how best to build a baseboard. Released in 2009 as Revision1, a new version is due out soon to map the I/O changes brought about in Version 2.1 of COM.0 (Figure 1).

CompactPCI Goes Serial and Express
Ethernet just goes faster and faster. From 10Mbps up to 40Gbps, we’ve been discussing the “serialization” of Ethernet applied to COM Express. But it was on an open standard CompactPCI variant called PICMG 2.16 that in 2000 facilitated the first switched backplane using plain vanilla Ethernet. It was released during the so-called “fabric wars” when, according to Pavlat, “Ethernet was number one then, it’s number one now, and it just keeps getting faster and faster.”

Figure 1: PICMG’s COM Express Carrier Design Guide is due for a refresh soon because of all the changes in the COM Express spec that added higher speed serial interfaces. (Courtesy: PIGMG).(http://www.picmg.org/pdf/PICMG_COMDG_100b.pdf)

The original CompactPCI spec is nearly twenty years old, was released in 1995, used the then-new parallel PCI bus, and was based on the familiar (and well-accepted) 3U/6U Eurocard standard. Unlike its quasi-competitor VME which is also based on the Eurocard, it wasn’t aimed at the military market and was “much cheaper than VME.” Successful in commercial markets galore, “cPCI”—as it is sometimes called—actually did find its way into mil/aero/defense/space applications because the 3U size meshed perfectly in smaller 1/2 ATR( short) avionics boxes and had ample I/O on the multi-row connector.

According to PICMG’s Pavlat, the newest Mars Rover Curiosity is controlled by CompactPCI (http://members.picmg.org/apps/group_public/document.php?document_id=6418). The two Rover Computational Element (RCE) cards are radiation-hardened PowerPC 3U cPCI modules built by BAE.Pavlat says that BAE claims that about 70 percent of satellite missions today use CompactPCI.

PCI Express was added to CompactPCI in 2005, but driven by National Instruments, a Revision 2 version of the CompactPCI Express specification was released in April 2013. The new spec quadruples the bandwidth to 5 Gbps transfer rate and 8 Gbps transfer on PCIe. Interface- and product-level interoperability was given careful consideration because unlike the COM Express market, instrumentation customers do care about backward compatibility and maintaining legacy systems. Besides performance improvements, Rev 2 clears the way for modern revisions and I/O updates to the (non-PICMG) complementary test and instrumentation specification called PXI. CompactPCI Express Rev 2 “has parallel interfaces, like the old CompactPCI, some serial interfaces like the newer CompactPCI Serial, but extra pins and functions for instrumentation users like clocks and triggers,” says Pavlat.

In Europe, MEN MikroElektronik pushed forward a new specification called CompactPCI Serial in 2011 which replaces parallel interfaces with high-speed serial: SATA, PCI Express and Ethernet on the backplane. Driven by MEN’s customers in the transportation and industrial control markets, “It really gives CompactPCI a mid-life kicker,” says Pavlat, “and depending upon how you build the backplane, you can use old CompactPCI cards as peripherals if you want, or build the system entirely out of CompactPCI Serial cards.”

All totaled, says Pavlat and a press release (http://picmg.org/officersadmin/NewsPDFs/CompactPCI%20Express%20Enhancements%20-%20PICMG%20PR.pdf) issued by PICMG in April 2013, the market for all things CompactPCI “represents well over $400 million in annual revenues,” making CompactPCI one of PICMG’s most successful specifications.

Figure 2: JPL’s Mars Rover Curiosity uses dual CompactPCI boards designed by BAE Systems. (Courtesy: PICMG, NASA, and JPL.)

AdvancedTCA: HA and Hot Swap Spawn MicroTCA

PICMG’s third major specification series is xTCA which includes AdvancedTCA (ATCA), Advanced Mezzanine Card (AMC) and MicroTCA. The AdvancedTCA market, according to Pavlat, is somewhere between $1.5B-2.5B per year, primarily driven by the telcos in applications ranging from central office switches to cellular base station back haul equipment. Conceived in 2001 by a collection of telco companies looking to focus on their software IP instead of building proprietary hardware that added no value, “ATCA is our most successful specification to date,” says Pavlat, “because it had the most direct customer input. It’s been a huge success.” The requirements documents that drove ATCA came from companies such as Alcatel, Lucent, Nortel, Motorola and more.
Technically, the most important feature of ATCA is the high-availability, managed architecture that makes sure if something fails, another entity takes over. In fact, the extensive infrastructure—enabled by infrastructure standards such as IPMI—monitors fan speeds, voltages, currents, temperatures and is capable of predicting the failure of a fan, for example, weeks before it fails. “With over 30 years of mostly proprietary HA experience,” asserts Pavlat, “the telcos knew what they wanted and needed…” Part of that architecture required a bladed architecture that could evolve with changing processor standards such as Intel Xeons and packet processors, but also included a hot-swappable, HA mezzanine card with I/O tailored to each system requirement.

The result was the Advanced Mezzanine Card (AMC), which spawned its own card standard called PICMG MicroTCA (or µTCA for short).Ratified in 2006, the specification MTCA.0 is going on eight years old and has itself spawned four subsidiary specifications (Table 3). Small and compact, AMC cards plug into a backplane that forms an HA, hot-swappable system “ that gets close to the two-level maintenance holy grail in military and defense applications,” chuckles Pavlat.

Like the story in 3U CompactPCI, the military was searching for a lower-cost alternative to the very rugged ANSI VITA 1 (VME) specification. The first version MTCA.1 in 2009 was a “slightly rugged” air-cooled version. But driven by companies such as BAE and Emerson Network Products, the hardened, conduction-cooled MTCA.3 was released in 2011.”The connectors, wedgelocks and other mechanicals were either influenced by or taken directly from lessons learned on VME and VPX,” says Pavlat. The multiyear effort was “extremely well-thought-out, extremely well-tested and was followed by an air-cooled version which was only ratified last month in April 2013,” says PICMG’s Pavlat. [At the time of my interview with Pavlat in May, MTCA.2 “Hardened Air-Cooled MicroTCA” had not yet been announced. Ed.]

Table 3: MicroTCA, a rugged offshoot of PICMG’s Advanced Mezzanine Cards, has multiple specifications. The appeal of MicroTCA is the high-availability, hot-swappable compact architecture and backplane. (Courtesy: PICMG.)

Rounding out the MicroTCA family is MTCA.4 aimed at the niche market for high-energy physics data acquisition in places such as CERN searching for the Higgs boson particle. MicroTCA Enhancements for Rear I/O and Precision Timing brings the high availability of MicroTCA to the thousands of detectors used in particle physics experiments. When there’s an uncertainty on the order of Avogadro’s number of creating or detecting a particle, scientists want the electronics to work reliably and keep on working should something fail, without having to power down the accelerator. It turns out that the original high-availability goal of ATCA is finding greater traction in many niche markets, from military to instrumentation and control.

And what of ATCA itself? Pavlat recounts a presentation by Verizon’s CTO at the 2012 ATCA Summit which stated 60 percent of all telecom traffic is video driven by smartphones, expected to climb to a whopping 80 percent by 2015. “They need a 60-fold increase in total network bandwidth within 10 years to hope to pull this off,” remarks Pavlat. ATCA reached a major milestone in 2012 when the standard for 40Gbps Ethernet was released.

“ATCA has been 10Gbps/channel Ethernet since the very beginning,” says Pavlat. “PICMG 3.1 R2 quadruples the bandwidth of a single chassis. A full mesh chassis can handle 10 Terabits/s of data across 256 channels!” This rate is exceptionally important for the telecom industry given the constraints of size, power and legacy rack space traded off against the industry’s bandwidth forecast. Other updates during 2012 include the introduction of Hardware Platform Management HPM.2 (LAN-Attached IPM Controller) and HPM.3 (DHCP-Assigned Platform Management Parameters), which enable more remote management capabilities, among other things.

Not content to rest on their heels, PICMG members will later in 2013 be defining ATCA extensions and enhancements that will “describe how to build double-width modules, increase power from 400W to 800W and eventually put hundreds of gigabits of cheap DIMM memory in the double-board sandwich,” asserts Pavlat. In effect, this should make ATCA more attractive to the high-end server market by alleviating the need for more costly, 45-degree low profile DIMMS used in single high (1.2-inch pitch) ATCA boards.

Bandwidth: It’s What’s for Dinner
As my time with Joe ran short, I asked him to summarize the frenetic pace of PICMG over the last twelve months. “It’s the insatiable need for bandwidth in what I believe is the largest, or one of the largest, markets on earth. We’ve gotten to 40Gbps on copper and I’m pretty confident we’ll get to 100Gbps before long,” he muses. But he sees the day coming when copper will “run out of gas” and PICMG will need to add optical on the backplane. Reflecting back on the plethora of specs PICMG has launched in the last year, I wonder how many of those will eventually need to be revised one more time…just to add fiber.

It’s certainly exciting. These high-end HA features found on all of PICMC’s initiatives will eventually move down into embedded and ultimately into consumer electronics, which is perhaps the biggest global market of all. Summarizes PICMG’s Pavlat: “I’m a convert towards cheap electronics running high availability. It’s the new paradigm.”

ciufo_headshotChris A. Ciufo is editor-in-chief for embedded content at Extension Media, which includes the EECatalog print and digital publications and website, Embedded Intel Solutions, and other related blogs and embedded channels. He has 29 years of embedded technology experience, and has degrees in electrical engineering, and in materials science, emphasizing solid state physics. He can be reached at cciufo@extensionmedia.com.

Joe Pavlat has been president and chairman of the PCI Industrial Computer Manufacturers Group (PICMG) since 1995 and was directly involved in the development of both the CompactPCI® and AdvancedTCA® standards.

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