AXIe products reach the market

Two of the AXIe standard's founding companies are building a base of chassis and system modules, and all three founders are working to increase AXIe's versatility in test applications.

Richard Quinnell -- Test & Measurement World, 3/1/2011 12:00:00 AM

Following an exceptionally fast track for a new modular standard, AXIe products have now started showing up in the test market. Two of the standard's three founding companies are actively building a base of chassis and system modules and expect to release more in 2011. All three are pushing to increase AXIe's versatility in test applications, although they are using slightly different approaches. AXIe (ATCA Extensions for Instrumentation) began when Aeroflex, Agilent Technologies, and Test Evolution founded the AXIe Consortium in November 2009. Within seven months, the organization had released its initial hardware specifications, and products began appearing at the end of the third quarter of 2010. "This is the fastest-growing standard I have come across," said David Poole, CTO of Aeroflex Test Solutions.

This rapid development stems in part from the consortium's adoption of the ATCA (Advanced Telecommunications Computing Architecture) standard as its base. "ATCA has been widely adopted, offers modularity through the use of mezzanine cards, has the advantage of large board size, offers a mesh computing architecture, and can use PCI Express [PCIe] as the data bus," said Poole. The use of PCIe on the ATCA backplane gives AXIe a high degree of compatibility with PXIe (PXI Express) hardware and software, which will allow PXI modules mounted on a carrier card to be used in AXIe systems and provide an immediate base of test functions for AXIe systems.

The AXIe standard has also evolved quickly because it meets a need for larger-format modules than PXI can provide-a need that companies had already begun to address. "The size, power, and form factor of PXI are not sufficient for some applications," said Von Campbell, Agilent's planning manager, Modular Product Operation. "We were designing an internal standard for large-format modules when we were approached by the others [in the consortium] regarding AXIe. There was a lot of similarity and synergy between the efforts."

"The whole target [of AXIe] was to provide much more real estate than PXI could offer for designs where you want everything to fit onto one module," said Aeroflex's Poole.

One such design is digital pin testers for ATE (automated test equipment), according to David Oka, VP of engineering at ATE developer Test Evolution. "PXI is good for RF and AC testing [in ATE]," said Oka. "What's missing from PXI is lots of DC channels and lots of digital pins. There is not enough space when trying to build a 1000-channel tester."

Taking different tacks in AXIe development

Beyond the large-module format, AXIe offers other advantages over PXI, although the consortium founders are exploiting these advantages in different ways.

The higher power limits of AXIe modules are especially interesting to Agilent with its goal of bringing its measurement expertise to a full range of modular form factors. PXI limits modules to 30 W of power, while AXIe allows 200 W per module-a better match for porting box-like instrumentation.

"A lot of high-end ICs and ASICs draw 30 W already," said Steve Narciso, R&D manager for Agilent's Modular Product Operation. "So, we need the extra power of AXIe."

Test Evolution likes the connectivity that AXIe offers from the backplane. Unlike PXI, the AXIe specification includes a backplane area called Zone 3 that users can define. This area allows AXIe instruments to use rear transition modules rather than front-panel connections to link with a test fixture.

"PXI needs costly cabling to connect to a test fixture," said Oka, "which also makes it difficult to change fixtures." Oka explained that attaching the fixture to the rear transition modules not only simplifies connection but also provides more repeatable timing at the DUT (device under test) socket.

"Production ATE timing is adjusted to be correct at the socket," he said, "which is hard to do with uncontrolled cabling to fixtures."

Aeroflex's goal for AXIe is more strategic than immediate. "We were interested in AXIe from a theoretical viewpoint for future efforts," said Poole. "Any such standard is attractive. You never know what you're going to need."

Poole also noted that Aeroflex's participation in developing the standard was an investment toward reducing future design efforts. "It [participating] ensures that if you have a future need, it is easier to get your stuff ported [to the standard]."

AXIe product offerings

These differing areas of interest are reflected in the products each of the companies is offering. Aeroflex, for instance, is not yet producing any AXIe products. According to Poole, PXI currently provides the level of modularity the company needs, although he expressed interest in the multiprocessing potential of AXIe's mesh network structure and in the consortium's plans to eventually develop a small form factor.

Agilent has focused its initial AXIe efforts on creating a base for future instrumentation. In September 2010, the company released a two-slot (M9502A) and a five-slot (M9505A) AXIe chassis, each with a built-in controller module (Figure 1). The company also released the first AXIe instrument-the U4301A PCIe Gen 3 analyzer.

Fig. 1. The five-slot M9505A AXIe chassis with a system module from Agilent Technologies occupies the same 19-in. rack space as a PXI chassis, but it provides much more circuit and power-handling capacity. Courtesy of Agilent Technologies.

The M9505A makes clear some of the advantages AXIe brings to test design, according to Agilent's Campbell. The chassis, which mounts the AXIe modules horizontally with the cooling system adjacent, fits into a standard 19-in. rack. Campbell pointed out that a 4U-high PXIe chassis occupies essentially the same rack space, but the AXIe chassis offers designers much more capacity.

The five AXIe modules together provide a total of 4500 cm² in board space and can handle 1000 W of power. The 17 instrument cards in the PXIe chassis total 2720 cm² in board space and support only 510 W. Thus, according to Campbell, the AXIe chassis offers the equivalent of at least 25 PXIe slots in the space of 18.

Test Evolution's first AXIe offerings target its primary business of ATE equipment development. The Ev500 test system uses a five-slot AXIe 3.1 chassis and provides single-site characterization for a DUT. The Ev2800 uses a dual 14-slot AXIe 3.1 chassis and a 20-slot PXI chassis to provide multisite DUT support and a production test head with more than 1000 channels.

To create these systems, Test Evolution developed its own AXIe modules and chassis, which are also available as stand-alone products. The DD48 dynamic digital pin card offers 48 channels, each with 64 Mbits of capture-and-send memory.

The DPS12 device power supply module provides 12 output channels-which can be ganged-with multiple voltage and current ranges. The module can provide a forced-voltage test and then measure current with 16-bit accuracy, and it offers programmable pulse generation. The company also offers a chassis interface system module for AXIe that functions as both a slot-1 controller and a PXIe hub.

Starter kits available

Oka said that Test Evolution sees AXIe as an open-standard alternative to proprietary designs for semiconductor ATE that also promises significant cost savings. To help fulfill that promise, Test Evolution is offering AXIe products that support custom designs.

One is an AXIe starter module that implements all the system interfaces and leaves a large open area on which developers can attach a rider card containing their own designs (Figure 2). The starter module has an open schematic design and open-source software driver, simplifying the conversion of a developer's rider-card design into a full AXIe module.

Fig. 2. This AXIe starter board from Test Evolution furnishes the power and system interfaces, leaving most of the module open so developers can add a custom rider board. Courtesy of Test Evolution.

Test Evolution also offers a 14-slot chassis with an open framework to support prototype development. The open cage exposes the cards in a way that eases access for probing and debug, a feature Test Evolution found valuable in its own debug efforts. "It was hard to work with cards in a closed chassis," said Oka.

While commercially available AXIe products are still scant, the ones that are available provide test engineers with a basic framework from which they can begin creating their own modules. In that effort, Agilent's Campbell offered some advice. "If you can do things in CompactPCI and PCIe, you're a long way toward being able to use AXIe," he said.

He added, "Also, AXIe software is essentially identical to PXI, so use the same software architectures. Take advantage of what you know in PXI; don't try to be different."

Campbell also advised developers to think about a layout with regard to airflow across the AXIe board. An AXIe board can contain several copies of the circuit from a PXI module, and Campbell pointed out that designers often simply line up functions when replicating them on a larger board. That tends to cause heat sinks to line up and block one another's airflow. "Make sure things don't line up," he said.

If developing your own AXIe board is not an option, you may only need to wait a little longer for more modules to become available. Agilent's Campbell promised, "We'll see a whole lot more product coming out in the next calendar year." He added that "the test community should be looking at what they want in the AXIe format" to help define future offerings.

Meanwhile, the standard continues to evolve. According to Aeroflex's Poole, the AXIe Consortium is defining a standard implementation for a PXI carrier card and has a MicroTCA version of AXIe on its roadmap.

"There is still quite a bit of work to do," Poole said. But the potential is clear. AXIe has launched and is building momentum, promising to substantially raise the bar for modular test instrumentation. "AXIe is for companies looking to push the envelope," said Poole.

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