Quoting Philip Pemberton : > ... > US Patent number 6,108,751, granted August 22, 2000. > PDF here: http://www.freepatentsonline.com/6108751.pdf > ... > .... Bit of a mouthful, but there you go. Won't expire for another ten > years, near as I can tell. Wow, that's odd -- a different patent #, and a few years later than =20 the one Russell found. So does this mean that there was a correction (possibly because of the =20 Lexmark lawsuit) and a new patent number? Guess I'll find some =20 answers when I read these. > ... > IMHO there is a fair bit of prior art. If you took the signal from MSF > (the Rugby / Anthorn time signal), converted to baseband and sped it up, > you'd end up with something similar to 1-Wire. It's basically > pulse-width modulation. If all you've got is one wire, PWM is pretty > much the only game in town. > ... When I think of PWM, I think of unidirectional signals with many =20 different duty-cycles, such as RC servo control signals. From what I =20 remember of 1-wire from a few years ago, there was a time slot for =20 requesting and reading back whether a bit is '0', then another slot =20 for requesting and reading back if that same bit is a '1', so it did =20 two checks for each bit. > If you don't claim it to be 1-Wire (call it PWM-Bus or something) and > don't implement some of the more esoteric bits of the protocol (i.e. use > it as a physical-layer with your own link-layer protocol) you might be > able to get away with it in the same way lots of companies got away with > making I2C EEPROMs... call them something else. 2-wire, MicroWire, "two > wire addressable serial bus"... Or I can just create my own protocol. What I'm doing is not rocket =20 science, and fairly low speed, so I can do some sort of serial with =20 the master telling each slave when to send over it's data. I don't =20 plan to implement unique serial numbers, because the only thing I =20 didn't care for with 1-Wire is that the order of the slaves (such as =20 multiple temp sensors) was unknown until after they were connected. =20 Yes, it can be corrected in software (with the user indicating which =20 one is sensor 1, sensor 2, etc) or by physically swapping sensors =20 after that. And I don't need it to be 1-wire compatible. Thanks, -Neil. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .