> i have a star topology with serial resistors > (about600..800 ohms) in the scl and sda wires at each node. > that works fine! Don't try this at home, folks. A number of standard IIC devices may not work this way, or may even get damaged. The IIC bus is specified with a maximum sink current of 3mA on each line. If you're going to recommend something like this, please point out that you are only using IIC protocol, not true IIC. I assume you are using your own line drivers and not connecting off the shelf IIC devices to the bus, right? ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, olin@embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.