> can someone tell me the name of the transmission protocol that is self > clocking There are many communications schemes that don't require a separate clock signal or require the transmitter and receiver to agree on a clock frequency in advance. Manchester encoding is popular because it makes good use of the bandwidth. > and where can I find any info on it. The net, of course. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.