On 06/18/2012 02:57 PM, Eric Vickery wrote: > On 6/16/2012 3:27 PM, Eloy Paris wrote: >> Hi Phil, >> >> On 06/16/2012 07:43 AM, Phil White wrote: >> >>> On 13 June 2012 02:01, Eloy Paris<[email protected]> wrote: >>> >>>> All 1-Wire devices have this "presence pulse" feature that you mention >>>> -- that's a fundamental part of the protocol, and all slave devices need >>>> to generate a presence pulse right after they detect a reset pulse >>>> generated by the master. >>> My belief is that this statement is not correct - and it is this that >>> has caused the confusion and prompted the original question. >> I have no experience with the DS1990A and DS1990R, but after seeing your >> comment that my statement above is incorrect, I read the datasheets for >> both and I still see no indication of a slave that can act on its own, >> i.e. without the master initiating communication first. A slave that can >> do that (initiate communication on its own) would be speaking a protocol >> different than 1-Wire, or a 1-Wire protocol extension that I have never >> heard of. > There is a way for slaves to announce their presence on the bus by providing > a presence pulse when > they are powered up. I'm not sure if all slaves to this or just some (or all) > of the iButtons. Also > I don't know which masters or software supports this, it is mainly used for > things like door lock > systems where the iButton is used as the security FOB.
That's pretty weird. That'd kill any communication initiated by the master that is taking place when the iButton is powered up. Not saying I don't believe you, especially since I have no experience with these devices, but I'm tempted to order a sample just to further my knowledge of the protocol (and a possible extension to it like the one being discussed) ;-) Cheers, Eloy Paris.- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
