Santa Clara, CA, February 2, 2010 – The Small Form Factor Special Interest Group (SFF-SIG), a collaboration of leading suppliers of embedded component, board and system technologies, today announced the availability of revision 1.5 of the SUMIT (Stackable Unified Module Interface Technology™) Specification. This new revision offers two significant improvements over previous versions. First, it describes the implementation of USB channel shifting in SUMIT-based systems. Channel shifting in stackable systems means that when an I/O card consumes a resource such as a USB channel or PCI Express lane, it shifts the remaining available resources of a like kind to the pins used by the consumed resource when they are passed to the next I/O card above it in the stack. For example, an I/O card that uses USB channel 0 would shift channel 1 signals to channel 0 pins, channel 2 signals to channel 1 pins and channel 3 signals to channel 2 pins when these signals are passed up the stack. No special hardware or software decoding is required. Each I/O card is thus assured of a USB port being available on channel 0 up to the maximum number of USB ports provided by the base SBC. See Figure 1 for a graphic describing this feature.
Secondly, this new revision describes a simple, universal resource label which conveys interoperability of a company’s SUMIT-compatible product since all the interface signals supported by SUMIT may not always be supplied by a SBC or used by an I/O module. A SUMIT compatible SBC can provide PCI Express™ (up to 6 x1 lanes, or 2 x1 and 1 x4 lane), up to 4 USB 2.0 ports, LPC, I2C and SPI interfaces, along with 3.3V and 5V power, to the SUMIT compatible I/O modules above it in the stack. Intended for data sheets and other product documentation, the resource label for an SBC quickly shows the resources made available by an SBC on the SUMIT connector(s). Likewise, the resource label for a SUMIT-compatible I/O card defines at a glance the resource(s) consumed/required by the I/O card. Systems designers can match the labels of the I/O cards in a system against the SBC resource label to determine if the required interfaces and power are available. See Figure 2 for an example of an SBC resource label and Figure 3 for an example of an I/O card resource label.
SFF-SIG released the original SUMIT Specification in April, 2008 to provide an advanced, robust and reliable multi-technology board to board interface for stackable systems regardless of form factor based upon the new generation of low-power high integration microprocessors such as the Intel® Atom™ family and VIA Nano™ family using high speed serial bus technology. The new SUMIT revision may be used with either ISM or Pico-I/O form factor stacks plus other standard or even custom form factors. The new revision 1.5 of the SUMIT Specification is fully upward compatible from previous revisions and may be downloaded freely without registration from www.sff-sig.org/sumit.html
About the Small Form Factor SIG
The Small Form Factor Special Interest Group is an international organization devoted to identifying, creating, and promoting standards that help electronics system and device manufacturers and integrators move to small form factor technologies and building blocks in their products, and protect their investments. Benefits of small form factor products include smaller size, reduced power consumption (eco-friendly, “green” products), and greater reliability compared to larger legacy products. The SIG’s philosophy is to embrace the latest technologies, as well as maintain legacy compatibility and enable smooth transition solutions to next-generation interfaces. For more information about the SFF SIG, visit www.sff-sig.org or e-mail info@sff-sig.org.
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