1993 patent appears to be 5210846 Here's a 1998 discussion on Dallas 1 wire appolication. Refence 1 cites a 1997 paper. That's 13 years - about at the upper limit of any patent that may have applied originally. http://archives.sensorsmag.com/articles/0698/wir0698/index.htm Half duplex on a single pair was used since time immemorial and hald duplex with ground return was used by Noah in the ark ((had problems due to poor ground). Atmel think they/you can do it http://www.atmel.com/dyn/resources/prod_documents/AVR274.pdf 2000 http://www.sensorsmag.com/sensors/humidity-moisture/a-1-wire-humidity-sen= sor-1080 1997 Feb. 1997. "Transmitting Data and Power over a One-Wire Bus," Sensors, Vol. 14, No. 2:48-51. Text from 1997 paper here http://www.datasheetarchive.com/datasheet-pdf/03/DSA0036838.h= tml Related http://blog.onlinecomponents.com/post/buddy-can-you-spare-an-i-= o-pin-try-a-1-wire-interface Patent litigation 1998, re 1993 patent http://www.uspto.gov/web/offices/com/sol/og/1998/week30/patrequ.htm On 24 September 2010 01:57, PICdude wrote: > Sometime years ago, I had heard (IIRC on this forum) that 1-wire > technology is patented, such that I can't implement my own slaves. > I've not come up with the patent yet, and Maxim hasn't responded to me > yet. =A0Anyone know if this is true, if the patent is still valid, and > what the general details are? > > I want to bi-directional communication to a PIC application, and have > only 1 wire available. =A0I also have no room for additional (1-wire > slave) chips, but that would be pointless anyway as that slave chip > would need more than one wire for communicating with the PIC. > > If this is not doable, I may end up rolling my own protocol that can > work with a single wire, but I'd need to know what specifically is > patented with respect to 1-Wire technology. > > Cheers, > -Neil. > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .