Bob Burckle on small form factor computing

 

WinSystems vice president Bob Burckle has been involved in small form factor computing since the late 1970s and the days of STD Bus. How do small industrial computers stack up today, four decades later? What’s been the impact of high-speed serial links? How powerful are legacy interconnects? Burckle discussed these questions, the schism between the PC/104 Embedded Consortium and Small Form Factor Special Interest Group (SFF-SIG), and other topics with Open Architecture Review. 

OAR: What are tha major trends you see in embedded computing today? 

Burckle: When you look at things from the 30,000-foot level, the big picture is “How do I get I/O out of a computer?” How do you attach one of the latest generation processors to an application and make it useful? Just having the best performance from a processor module doesn’t do you much good without the right I/O.  

Another issue is size.  We see more and more functionality packed into less and less space.  Designers are faced with issues of heat, packaging and interconnect technology. 

Finally how do you balance legacy vs. the newest technology?  We see this with PCI Express [PCIe] replacing PCI, USB replacing COM, LPT, mouse and keyboard interfaces, and SATA replacing PATA on the newest processors and chipsets.

 OAR: What’s the “right” I/O?  

Burckle: There’s a plethora of different answers to that question which are dependent upon whether it’s a commercial, industrial, medical or military environment. One needs to consider the issues of functionality, as well as physical interconnection, safety, security, redundancy, RFI/EMI, regulatory compliance, extended temperature operation, plus shock and vibration. System designers need to take different paths to provide the same basic I/O in different environments, especially as it relates to areas of ruggedization. 

OAR: What about in the stackable small form factor world? 

Burckle: What we’re seeing in the stackable realm are different architectures and products from a number of different vendors and standards organizations, all trying to address the same issue: how to get from the real world to the digital domain to wherever the final decision making or monitoring has to occur. What differentiates different approaches is how they package it and balance the amount of I/O power, the size of the connector, the size of the board, etc. Typically what we’re finding is that smaller is better for more and more applications. 

OAR: WinSystems is a member of both the PC/104 Embedded Consortium and the Small Form Factor Special Interest Group, which have competing approaches to bringing the PC/104 framework into the modern age. You’ve opted for the SFF-SIG’s architectures: SUMIT  (Stackable Unified Module Interconnect Technology) and COMIT (Computer on Module Interconnect Technology). Why? 

Burckle: First of all, SUMIT is a connector specification, not a form factor. It allows boards to be stacked together while supporting high-speed signals such as PCIe Gen2. This allows the smaller SUMIT-enabled interconnect solution to be used on a variety of different boards from as small as a 60 x 72-mm Pico-I/O modules to a 5.75 x 8.0-inch EBX-sized board.  

SUMIT represents an amalgamation of a number of very popular interfaces that we’re continuing to see on new x86-based silicon from major semiconductor companies. And that’s PCI Express, USB, LPC Bus, SPI/Microwire and SMBus/I²C Bus. 

From my perspective, as well as that of other embedded companies, SUMIT has the best mix for our particular customer base, especially since it [the SUMIT connector] can be used on different SBCs or I/O cards while taking up a very small amount of space yet supporting tremendous processing power. 

OAR: Why include low-speed buses such as LPC and SPI in the SUMIT mix? 

Burckle: LPC and SPI are gradually replacing the popular ISA bus. These signals are supported in the latest generation of chipsets since they reduce total pin count while still offering an easy, cost-effective way to interface with simple I/O devices. 

If you’re going to do something like toggle a relay on or off, using PCI Express is like trying to get a drink of water out of a fire hose. The data’s coming out so fast and hard that you have to add bridges and software to be able get the data down to where you can use it. So you think to yourself, “Isn’t there an easier way to do this?” And the answer is “Yes!” So it makes sense to dedicate a small number of pins to do such things. The LPC bus is particularly useful for that, as well as providing a bridge to support legacy ISA bus devices on PC/104 cards. 

OAR: When SFF-SIG splintered off from the PC/104 group a few years ago, it reminded me of the STD schism in the early ‘90s over the issue of 32-bit expansion. Is this the same kind of schism? 

Burckle: Unfortunately, yes. It comes down to a philosophical difference between two groups. The SFF-SIG’s charter is devoted to identifying, creating and promoting standards that help companies move to small form factor technologies in their products in order to protect their investments over the long term. The SIG is focused on the new ultra low power and mobile processors, as well as other emerging technologies. 

The Consortium’s new specification supports PCIe expansion on a 90 x 96-mm board but no longer directly supports PC/104 modules since the PCIe connector occupies the exact location of the PC/104 connector, forcing its obsolescence. This requires another interface board to convert either PCI or PCIe signals to ISA so that existing off-the-shelf standard or customer-designed PC/104 boards can be added to a stack. 

The Consortium also opted for a x16 PCIe, which requires a larger, more expensive connector and does not support as many USB and other legacy interfaces. We feel that x16 PCIe may be appropriate for high-end video displays, but it demands too much power otherwise, creating cooling issues for small, stackable solutions. Moreover, x16 PCIe is not supported by the latest Intel Atom and VIA Nano families of low-power chipsets designed for the embedded market. Besides, most of that market already went to COM Express due to the advantages of using a simple heatspreader over custom heat pipes and milled aluminum blocks. 

In my opinion, these issues are show-stoppers. We weren’t able to philosophically work out our differences, so we agreed to disagree. The SFF-SIG has come to market with our SUMIT-ISM [Industry Standard Module] solution, and embedded customers wanting stacking solutions will vote on the alternatives with their dollars and Euros as to which suits their needs best. WinSystems is still dedicated to PC/104-based products since the ISA bus is not EOL in stacking applications, and we will continue to introduce new products based on this popular worldwide standard.    

OAR: I can’t say I’ve seen much activity yet in SUMIT and even less in COMIT. Will this change?

Burckle: The SFF-SIG expects 2010 to be the breakout year for people designing them in, but SUMIT has the most activity based on the connectors showing up on PC/104 size boards plus EPIC and EBX size boards. You also have SUMIT-based products on Pico-ITXe and Pico-I/O boards.

COMIT is behind because it came out a year and a half after the SUMIT specification. However, WinSystems introduced the first COMIT-based SBC using Intel’s Atom processor at ESC/Boston in September 2009. Look for significant activity and new product introductions at Embedded World in March [this year] and the Embedded Systems Conference/Silicon Valley in April. 

OAR: There seem to me to be too many COM specifications around like COMIT. Couldn’t the SFF-SIG have adopted something that was already out there?

Burckle: We first surveyed the market of COM products in an attempt to use an existing standard.  However, none of them met our design goals at the time. 

OAR: Specifics? 

Burckle: The then-current PICMG spec, for example, only supported PCI, and we wanted a smaller, more robust, high-speed connector with one instead of two connectors to eliminate connector registration tolerances. For COMIT, we wanted to support at least second-generation PCIe, USB 3.0, SATA 300 and 10 Gbit Ethernet. For long-term availability, we didn’t want to define a product that we would have to redesign in a year or so. 

OAR: Frankly, I don’t understand the rationale for the ISM spec. Do I understand right that it addresses only board dimensions and mounting holes and that these are the same as for PC/104?

Burckle: Yes. The purpose of ISM is to define a truly open standard for modular, stackable systems.  Customers were confused about whether PC/104 refers to the bus, the board outline or both. We’re trying to codify, define and provide some semblance of clarity and structure within the multiple variations you’re seeing in 90 x 96-mm boards. 

The 90 x 96-mm board size has certainly become an industry standard module; however, there are multiple variations with connectors located in different parts of the board. It makes a great deal of sense to separate connector issues from the expansion board form factor. That lets you choose a different connector and place it where it’s most appropriate on the board. By sticking to the 90 x 96-mm “PC/104” form factor and mounting holes, you can upgrade a system using the same form factor and sometimes the same enclosure. 

OAR: Upgrade from buses to high-speed serial links? 

Burckle: Yes. The challenge for small form factor suppliers is how to embrace the next generation mobile and ultramobile chipsets coming out from Intel, Via, AMD and others in that space. We’re in a transitional period right now and, to use a Texas colloquialism, we’re beholden to the semi vendors and have to use what they provide. 

OAR: The first PC/104 kicker was PC/104-Plus, which added a PCI bus to the existing ISA bus. SUMIT-ISM replaces the PCI bus in that specification with a selection of high-performance and legacy serial links. Why do you like that approach? 

Burckle: The main reason that SUMIT-ISM was defined and subsequently adopted by the SFF-SIG is that we don’t want to abandon existing customers that have designed or purchased PC/104 modules for years. Somewhere in the range of 50-80% of existing customer stacks include PC/104 (ISA) bus cards. If you’re using the PC/104 bus, you don’t want additional stack height or software changes for existing I/O cards from third party vendors or the customers themselves. To go out and summarily dismiss all that–to say “Sorry, we’re moving on and you’ve got to requalify with all new PCI boards and device drivers, or add a bridge card that increases the stack height by 0.6 inches”—is not cost or time effective and doesn’t make a whole lot of sense to me. 

SUMIT-ISM allows you to preserve the size envelope but doesn’t tie you down to the older I/O expansion. The PC/104 connector and PC/104-Plus connector together take up from 10 to 15% of a board. The SUMIT connector gives us about sixteen times the bandwidth of the PCI connector in about one-quarter of the space. 

OAR: Don’t you also support other approaches, as well? 

Burckle: Yes. Our product offering is evolving. We’re in transition and in two or three years, our product line-up will look different than it does today, but we wanted to make sure that we didn’t leave any of our customers behind. Newer Intel and VIA chips have dropped the ISA bus entirely, so we can use LPC and SPI [on a SUMIT connector] to replace it for low-speed signaling. In that case, we don’t need the PC/104 connector and it can drop off. 

OAR: What’s an embedded computer company’s biggest challenge today? 

Burckle: Managing obsolescence coupled with the rapid movement of technology, and that’s our customers’ biggest problem, too. But if we have good open standards, then when a particular device is no longer available for whatever reason, we can probably expect to replace its functionality with little or no impact on anyone’s wallet. 

OAR: That sounds easier than it probably is. 

Burckle: Yes, but it’s the tightrope all of us in the technology field have to walk. 

OAR: Meanwhile, as we travel into the future, tell me how powerful is legacy when it comes to industrial computing interfaces? 

Burckle: Remarkably. We’re still making Z80 and 8085 STD boards that we made 20 years ago because people still want them. When Hurricane Katrina hit, we had refineries calling and asking for replacements for an STD Bus processor and I/O boards with an NSC800 [National Semiconductor microprocessor], and some of the earliest express deliveries going into Louisiana were these boards to get the refineries back on line.

OAR: You don’t actually have STD boards available off the shelf when people call, do you?! 

Burckle: Many we do, and others we just have bare boards; it’s a function of inventory control and how active the products are. If just a handful are trickling out, we may have pretty much brought them down to zero. With the Katrina example, we had enough boards in finished goods stock. We just needed to add conformal coating. In other instances, if we have the bare PC boards in stock, we try to find enough components to build the boards. 

The revolution is coming with SUMIT and all the new interfaces, but it’s important to support existing customers as long as possible because in a lot of cases, the engineers who designed their products aren’t there any more, and it’s a tremendous burden for a customer to go back in and redesign everything. If it’s possible to manufacture, test and warrant old products, we will, until it’s no longer physically possible.  However, we work with our customers to find a solution. 

In certain instances, we have no choice. If we can’t get the components and the manufacturer stopped making them, then we’re dead in the water. It seems a lot of times it’s the small stuff that bites you: an oscillator or baud rate generator or some PAL for combinatorial logic that we used many years ago that we can’t get anymore. 

Click SUMIT to see a white paper on SUMIT.  

Click COMIT to see a white paper on COMIT.