Hi Phil, On 06/12/2012 08:36 PM, Phil White wrote:
> Hi All, > > This may, or may not, be applicable to this list. However, I am hoping > that someone here knows enough about MicroLAN to be able to clarify > something for me. > > Up to know, all my sensors have been polled. Simplistically speaking, > the PC asks "What is the temperature now?" > > What I am pondering is the ability for a sensor to suddenly, without > any warning, say "Gosh! It's hot here". > > Now, some of the iButtons come with a feature called a Presence Pulse > - although I am also interested in getting events via a DS2408 switch, > and the DS18B20 comes with an alarm function. > > Questions: > Is this possible (preferable, but not necessarily, with OWFS) without > polling the chip all the time? > what are my options? The 1-Wire protocol does not allow for slave-initiated communications; everything is initiated by the master. 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. I think the closest option to a non-polling solution is to use the alarm function that some 1-Wire devices offer -- it still requires polling but it can minimize it since only devices in an alarmed state would be contacted. The way the alarm function works is that only devices that are in an alarmed state will respond to a conditional search, so then you would only read the sensors that show up in a conditional search. 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
