Created by the Small Form Factor Special Interest Group (SFF-SIG), a collaboration of board, I/O suppliers, and component manufacturers led by WinSystems, VIA Technologies, VersaLogic, Octagon, and Ampro, the SUMIT interface specification is intended to improve I/O issues in next generation, low power, expandable single board computers (SBCs). The interface specification combines high-bandwidth PCI Express lanes, USB ports, and lower-speed multiplexed and serial buses into two, 52-pin high-density (0.025” pitch) connectors with center ground blades for impedance, EMI, and DC ground return purposes.
Each connector is optional depending on the target applications of a particular SBC. The SUMIT Type A connector has one PCI Express x1 lane, three USB ports with global over-current signal, an LPC bus for expansion serial ports (and other legacy I/O, SPI / µWire), and an I²C bus. The SUMIT Type B connector adds another PCI Express x1 lane and a x4 lane. There are three valid configurations known as SUMIT-A, SUMIT-B, and for both connectors, SUMIT-AB.