I see your hack, which will certainly work. The delay was supposed to be not at the time of "simultaneous", but at the time of the first temperature read, so work could be done in between.
I'll include your change in the next release. Thank you for your work! Paul On Thu, Jan 6, 2011 at 2:20 PM, Jim Kusznir <[email protected]> wrote: > We did some hacking on the source code. With a very basic hack to > change the delay on a simultanous temperature command, alarming on > bus-powered 18b20's now work. I think this hack is not > production-ready, but it does appear to be a fairly easy fix. > > --Jim > > On Tue, Jan 4, 2011 at 3:34 PM, Jim Kusznir <[email protected]> wrote: >> Hi all: >> >> I've been reporting for a while that alarming was not working with >> DS18B20 temperature chips. Today we have finally gotten the traces >> and compared to the Dallas data sheets to figure out exactly why >> they're not working. >> >> Thanks to the relatively new bus traffic debug feature, we were able >> to get this. >> >> It appears that all the alarming setup stuff works. We did find a bug >> in the reading of the alarm values: owfs only reads from the >> scratchpad; it does NOT first copy from the alarm EEPROM to the >> scratchpad. Therefore, unless you just set the alarm value, the value >> OWFS reads out is actually not correct. >> >> After setting Thigh and Tlow, we entered into a loop of echo "1" > >> simultaneous/temperature followed by a ls of the alarm directory. In >> our case, the temperature chip always shows up in the alarm directory, >> even when it should not. However, if we cat fasttemp for a chip, it >> will disappear from the alarm directory. >> >> Today's research revealed that the issue is that OWFS is NOT handling >> the bus powered situation correctly. It looks like the alarming >> function would work perfectly if all of our DS18B20s were externally >> powered. However, we run all of ours parasitic. I suspect that some >> logic needs to be added to OWFS to "know" if it has at least one >> bus-powered chip (there's a simple OW command that can be run to do >> this, IIRC), and then it would need to execute the strong pullup after >> a convert command. >> >> Thanks! >> >> (BTW: our test version of OWFS 2.8p3 with owtraffic, used with the >> dallas USB bus master blows up randomly with cannot reconnect errors; >> 2.8p2 worked stably. We did not check 2.8p4.) >> >> --Jim >> CASAS Lab Manager @ Washington State University >> > > ------------------------------------------------------------------------------ > Learn how Oracle Real Application Clusters (RAC) One Node allows customers > to consolidate database storage, standardize their database environment, and, > should the need arise, upgrade to a full multi-node Oracle RAC database > without downtime or disruption > http://p.sf.net/sfu/oracle-sfdevnl > _______________________________________________ > Owfs-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/owfs-developers > ------------------------------------------------------------------------------ Gaining the trust of online customers is vital for the success of any company that requires sensitive data to be transmitted over the Web. Learn how to best implement a security strategy that keeps consumers' information secure and instills the confidence they need to proceed with transactions. http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
