All, Has anyone used the I2C bit bang routines from the "SERIAL PIC'N" book? I am using the IISLAVE routines and am trying to get a master (PC) to send an address and a register select number to the slave and then have the slave send the contents of the selected register back to the PC. All works fine up to the point of the slave returning the register contents. The PC (Master) always seems to recieve all zeros. I've looked at the slave output with a scope and sure enough, I see all zeros. I've run this software through the simulator and it runs like a hose. But put it in a part (16F84) and it just doesn't quite work as planned. I know the simulator can't simulate everything, but I always thought it was very good at simulating the logic of my software. Does anyone have any ideas? I'd be grateful to hear from anyone regarding this. I've been working on this particular aspect for over a week now with no luck in getting it going. I've checked the archives but didn't find anything that dealt with this directly. So if anyone has any ideas, let me know at your earliest convenience. Thanks and Regards, Jim -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.