Brendan Gillatt wrote: > Many people will tell you that you can use a voltage divider for 5v -> > 3v and rely on the 5v logic's 2.5v threshold for 3v -> 5v conversion. > This may work but it is not bidirectional and sounds a bit iffy. I don't see anything iffy? All specs are met without waving of dead fish. There is a tradeoff between speed and current consumption with the resistor divider, but that is no different than the tradeoff of what family gate to use for the other direction. My standard answer is 2K ohms in series followed by 3.9K ohms to ground for 5.0V to 3.3V, but some cases may require lower values. 2Kohms // 3.9Kohms = 1.3Kohms, * 100pF = 130nS, so that should be good for up to 2MHz square wave considering 100pF is very high for on-board traces. Do you have any fact-based objection or is your comment just silly superstition? ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist