Freescale Semiconductor's 8640D rekindles SBC powerStory
September 19, 2008
Continued customer demand for more functionality and performance in the same or smaller space envelope, consuming less power, drives every new generation of SBC and DSP engine to stretch the limits of power dissipation in the highly competitive 6U VMEbus, VXS, and VPX rugged embedded computing market. Advanced semiconductor processing and packaging technology now offer COTS vendors the possibility to pack in more functionality and compute performance than can be adequately cooled.
Continued customer demand for more functionality and performance in the same or smaller space envelope, consuming less power, drives every new generation of SBC and DSP engine to stretch the limits of power dissipation in the highly competitive 6U VMEbus, VXS, and VPX rugged embedded computing market. Advanced semiconductor processing and packaging technology now offer COTS vendors the possibility to pack in more functionality and compute performance than can be adequately cooled, introducing the need for trade-offs to be made in some aspects of a product's characteristics.
The rugged, embedded mission-critical market still exhibits strong customer preference for Power Architecture devices and the VMEbus. This is the market's comfort zone with big investment by both vendors and their customers in applications development, system integration, tools, and hardware capability. Many of these customers are looking for the next generation of SBCs but are not yet ready for the complexity of migration to VPX, not necessarily needing more I/O capability or high-speed serial fabrics. The case for other processor architectures is often debated, and Intel's Core 2 Duo line of embedded processors, including the T7400 at up to 2 GHz, is certainly competitive in performance and power dissipation (between 20 W and 40 W). They also offer better integration with graphics. However, it is the application type that differentiates the processor choice. Intel will be selected for Man Machine Interface (MMI) applications and for network-centric, client/server architectures making use of off-the-shelf software solutions hosted on Solaris, Linux, or Windows. Power Architecture still dominates hard real-time, mission-critical applications, which are often custom developed to a specific platform type and must be robust and verifiable. Most of these applications are based on Wind River's VxWorks, LynuxWorks LynxOS, or Green Hills' INTEGRITY.
The Freescale Semiconductor 8641D is the high-performance processor device of choice for this latter class of application. Vendors offer the 8641D on both SBC and DSP products with as many as four dual-core devices per 6U module already available. However, because of the potential to exceed the module's cooling capability, it might be necessary to push and pull each end-user's application parameters to best effect. This can be done by using single-core devices, reducing clock rates, restricting PMC/XMC additions, limiting the operating temperature range, or using the wider 1-inch pitch of VPX to gain extra cooling capacity, for example.
The 8641D was designed for the next generation of serial fabric-based architectures offering integrated 1 GbE, Serial RapidIO, and PCI Express (PCIe) as replacements for parallel data paths such as PCI, PCI-X, and even the VMEbus backplane. While providing this wealth of high-speed serial capability neatly targeted to either VXS or the newer VPX standards, the 8641D, by virtue of its e600 processing cores, also presents an opportunity to upgrade existing VMEbus SBCs. The majority of these SBCs use G4 (7447, 7457) Power Architecture devices and a Marvell Discovery bridge to provide the parallel PCI and PCI-X buses that provide connectivity to multiple I/O devices, the VMEbus and, in general, two PMC sites. From a user's perspective, changing from an existing SBC's PCI/PCI-X to the 8641's PCIe will be transparent, allowing easy migration of applications from one generation to the next.
A number of VMEbus SBCs have also been offered with two G4 devices, using the Discovery's versatile crossbar switching to provide links between processors and shared peripheral or I/O devices. This produces an innovative architecture configurable with one or two processor devices that can be loosely or tightly coupled as required by the application. To upgrade these dual-processor SBCs to dual 8641D devices, each potentially dissipating 30 W, pushes the power envelope of VMEbus and brings with it the need yet again to consider some application-dependent restrictions or performance limits. The newly introduced low-power Freescale Semiconductor 8640D goes a long way toward resolving this dilemma by offering comparable performance to the 8641D, yet dissipating 25 percent less power. The VG6 dual-processor SBC from GE Fanuc Intelligent Platforms shown in Figure 1 supports either dual 8641D or dual 8640D processors plus two PMC sites, being customizable for performance, functionality, or power dissipation to suit a broad spectrum of end-use applications.
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The 8640D provides the boost needed for the next generation of VMEbus SBCs. In a dual-processor configuration, a quad-core SBC can be implemented that supports compatible I/O functionality plus PMC/XMC sites offering no-compromise power dissipation. VMEbus and Power Architecture still have a lot of life left in the marketplace, capable of offering that continuous, plug-in upgrade path when the next performance boost is required.
To learn more, e-mail Duncan Young at [email protected].