Elastic interface bus

=Overview=

Elastic Interface buses (EI bus connections) can be generalized as bus connections which are high speed interfaces that have clock sent with data. All of the data bits are aligned to the clock to be able to latch the data at these high speeds. It requires that the net topology and timing characteristics for each net on the bus are at cast similar to each other in order to make it possible to line up the edges of the data to the clock. In this environment re-working connections in the connection module were not easily possible due to the fact that all the nets had to have similar topology and timing characteristics. This increased the difficulty of a re-work solution or made it impossible. This increased the modules that needed to be scrapped as not usable.

Repair

The advent of Elastic Interface repair introduced the concept of a spare wire built in the bus interface in the connection module that had the same topology and characteristics of the rest of the nets in the bus. It includes the hardware to be able to switch from the bad net in the interface to the spare net. However this operation must now be supported from original manufacture and through out to the customer use in the field. The connection module is tested at several different process corners such as low and high temperature, low and high voltages are good examples of some of these process corners. When a net on the interface is known to be bad the spare net should be used on the bus for testing and the known bad net should not be tested. When the bus does not have a defect the spare net needs to be tested in addition to all the functional nets. In the original design specification for the EI spare not it was driven with a constant zero when not used. [ [http://www.peertopatent.org/patent/20080082878/activity Peer to Patent activity on US Pre-Grant Patent Publication Number: US20080082878 “System and method to support use of bus spare wires in connection modules” July 20, 2008] ]

Applications

IBM, inventor of the elastic inteface bus, uses it in it's PowerPC 970FX [ [http://www.ibm.com/developerworks/power/library/pa-nldec04-poweron/index.html Guillaume Peron, "IBM PowerPC 970FX power-on reset mechanism" 15 Dec 2005] ]

Mai Logic is a licensee of the Elastic Interface technology. [ [http://goliath.ecnext.com/coms2/summary_0199-1215399_ITM Mai Logic, Inc. Licenses IBM(R)"S Elastic Interface Technology For Its Articia Chipset Family and Teron Series Systems in Support Of IBM(R)"S Powerpc(TM) 970 Microprocessor Family. Press Release, 12/22/03] ]

ee Also

HyperTransport

References