RTC Magazine

An amazing thing happens when engineers and product marketers talk directly to customers and end users. This direct, unfiltered interchange provides not only “what” is required, but “how” and “why” specific choices are made. Applying this principle to the small form-factor computer arena provides a fresh round of customer data, which can be used to create standards with cohesion, consistency and stability over a 10-year-plus horizon.

Talking to users about their evolving small form-factor embedded computing needs is leading to a new set of governing standards that can move this fragmented market forward. Coordination and cooperation in what has become the fastest growing area of the embedded computing market can replace the lack of standardization and diffusion common today.

Decades of CPU-Driven Standards

For small form-factor SBCs, board-to-board interfaces have been nothing more than repackaged PC chipset buses for decades. Going forward, these CPU-centric notions must be re-examined, as pressures to bring more functionality into smaller spaces requires flexibility and leaves no room for inefficiency.

When looking at new processors or chipsets, once again the tendency is to bring their highest-speed buses to off-board expansion connectors, with the belief that anything slower can be created with bridge chips or FPGAs. After all, PCI Express is newer than the PCI Bus, which was newer than the ISA Bus. Imagine the possibilities with a PCI Express x16 interface! Now imagine the overhead and waste in this when running relays that operate traffic signal lights if only a x16 PCI Express interface is available.

It is quite easy to examine the current chipsets on the market and create a new interface standard that showcases the highest bandwidth bus. That is essentially how most previous board-to-board interfaces were defined. This approach automatically dictates a particular CPU architecture in a self-fulfilling prophecy. Considering PCI Express high bandwidth versus the low-speed I/O and 100-600 MHz processors used broadly in today’s embedded market, the big question is whether or not the I/O community can drink from a fire hose to supply many garden-variety peripherals of the future.

Power to the People

For the majority of system manufacturers and integrators, what their equipment does and how it operates is all about the application, hardware and software. The Small Form Factor Special Interest Group (SFF-SIG), a new industry collaboration of many types of suppliers, including component vendors, board vendors, power supply and enclosure designers, wants to give system manufacturers a voice regarding the standards that drive the embedded computers they will purchase in the future.

The SIG members have been out talking to embedded systems designers during the last 6 months. These customers are system OEMs who rely upon off-the-shelf embedded computer systems and boards for long-lived applications. The design alternatives of either proprietary (single-vendor) non-standard solutions or full custom designs are plagued with vendor risk and alternative sourcing issues. The open market has always thrived on choice, so it is appropriate to query customer needs and then create useful, multi-sourced standards from their input.

With all of the “legacy free” hype in the market, the members were a bit surprised to learn that in many cases, the concern was not about how many Gigabytes per second will need to flow across the board-to-board interfaces, but rather how easy it needs to be to continue to attach low-speed input and output devices in the future. It appears that rumors of the death of legacy peripherals and the ISA Bus have been greatly exaggerated. Some of the feedback we received is depicted in Figures 1 and 2. Figure 1 represents an aggregation of customer feedback regarding where the requirements for the majority of systems fall with regard to processor power and speed and the capabilities of the I/O.

Serial Ports

The venerable serial port has vanished from desktop motherboards. Many embedded processor boards continue to provide these thanks to legacy serial and super I/O devices. Whether synchronous or asynchronous, serial ports are mainstream in embedded systems, both as external DB9 connectors and as cabled board-to-board interfaces. Medical, industrial, point-of-sale and portable devices all require support for serial peripherals. Bar code scanners, cash drawers, keypads and low-speed wireless converters are just a few examples.