X marks the spot

Electronics Times, Nov 30, 1998

The x86 architecture is becoming significant in embedded designs. Nick Flaherty finds out why

Traditionally, the x86 processor was one of the last things you would think of to put at the heart of an embedded design. But the rules of design are changing and this architecture is becoming increasingly significant.

The performance of the chip, even for realtime systems, is not so much of an issue. Nowadays, a lack of latency can be addressed by using more cycles when the processor is running at 166 or 266MHz. Far more important factors now include power consumption, the long-term availability of the parts, the compatibility of software and access to of development tools.

The benefits of using x86 are clear - using the high volumes of the PC business, to take advantage all the support chips and buses such as PCI, and the range of applications available on Windows and Windows NT, not to mention a common look-and-feel for user interfaces.

But as more embedded designers move to the x86, other high-end PC technologies migrate down. This has already happened with the PCIbus, spawning the CompactPCI rack systems, and is happening again with I2O, the intelligent I/O specification commonly used in servers.

In the past month, the specification has been opened up to all designers, not just those who are members of the special interest group, and embedded software vendor Wind River Systems is extending its realtime operating system VxWorks to include key elements of I2O.

Of course, the x86 has already been at the heart of a number of embedded designs without engineers really noticing. AMD has been using the 16bit 186 core for its telecoms and networking products for many years now.

Bob McConnell, vice-president of AMD's logic products division, said: "We've found that there is a real desire for a low-cost, high- performance x86 processor core with integrated communications functions."

These controllers are aimed at a range of communications applications including xDSL modems, USB peripherals, ISDN terminal adapters, low-end routers, digital line cards, PBX applications, digital phones, digital loop carriers and key telephone systems.

"The x86 is mature, robust and has a wide range of tools and programmers to help bring products to market quickly," he said. "Plus, x86 offers scalable performance from 6.6mips in the Am186 microcontrollers to the K6 microprocessor."

And now the K6 core is making its way into the embedded world. AMD has announced that it is taking its sixth generation core from the desktop and into the embedded world as the K6E.

"The K6E gives our embedded customers a significant performance boost which enables them to produce superior products," said McConnell.

"For applications such as central office switches, point-of-sale terminals, information appliances and Windows-based single board computers, the AMD-K6E microprocessor is an excellent choice for OEMs looking to take advantage of the x86 instruction set.

"They can continue to use the industry's most prevalent architecture to produce products with high performance and fast time-to-market."

The 8.8 million transistor processor runs both 16 and 32bit software and supports Windows CE, Windows 95 and Windows 98 operating systems and applications, using the low-cost, high-volume Socket 7 infrastructure. It will be built on AMD's 0.25 micro m, five-layer- metal process technology at Austin, Texas.

Rex Meek, director of marketing and systems engineering at AMD's embedded processor division, said: "Our customers have made significant investments in their x86 embedded products, and the AMD-K6E microprocessor allows a path to greater performance while preserving much of their existing software.

"The x86 instruction set is mature, robust and has a wide range of tools and programmers to help bring products to market more quickly."

Intel is fighting back in the embedded market with 2.5V Pentium parts with MMX, built on 0.25 micro m processes so they can run without a heatsink. These processors are specifically intended to provide simplified, lower cost thermal management solutions for embedded system designs.

With core voltages of 1.9V and I/O voltages of 2.5V, the maximum power dissipation at 266MHz is down to 7.6W and to as little as 2.3W for the typical consumption for the 166MHz parts in new packaging.

The chips are also packaged for the embedded market, using the standard 296lead plastic pin grid array for Socket 7 and also a new 352ball grid array package. The HL-PBGA package has a small 35 x 35mm footprint and is only 1.45mm high.

The thermal properties of the package, combined with the low power dissipation of the processor, result in a 0 to 95 degrees C case temperature specification, which is 25 degrees C higher than the previous generation of Pentium processors with MMX technology. The temperature specification of the PPGA package has also been expanded to 0 to 85 degrees C for embedded applications.

These processors are supported by the Intel 430TX chipset, also on Intel's embedded roadmap. The chipset is two chips in a BGA package that provide mobile-style power management and memory interfacing.