Loren, >From what I'm hearing my problem seems to be fairly unique.
I'm using the LinkUSB bus master, not Hobbyboards. Paul W Panish Mobile: (603) 343-8901 > On Apr 29, 2015, at 21:03, Loren Amelang <lo...@pacific.net> wrote: > > On Wednesday, April 29, 2015 at 12:06 PM, > owfs-developers-requ...@lists.sourceforge.net wrote: > From: Paul W Panish <ppan...@panishnet.com> > Subject: [Owfs-developers] Temperature sensitive bus timing using DS18B20 > >> My problem is that there seems to be a strong temperature dependency for >> bus read/write errors caused by the DS18B20 sensors. I?ve replaced the >> sensors a few times with devices purchased at different times and from >> different vendors to rule out random bad devices. >> >> I?m using a polling loop to read the DS18B20?s and PIO inputs at 5 >> second intervals with a conversion resolution of 10 bits >> (temperature10). When the system is cold (<140 degrees F) it can go >> forever (months) with no errors indicated in any device access. However, >> when I fire the boiler I start seeing access errors (file not found) as >> the boiler temperature rises above roughly 150 degrees. The error rate >> increases as temperatures rise to a maximum level of about 185 degrees >> at which point they are quite severe. > > I would say there is no such problem with the 18B20 itself. I've had ten of > them strung around my house since 2002, from solar panels on the roof to the > wood boiler on the lowest level, easily 100 feet of CAT5 in a single bus with > the computer connected in the middle. The solar and wood sources regularly > take them to 160F and fairly often beyond 185F, occasionally over 200F, and > (unless I've done something transient to mess up the communication) I see > exactly zero errors. These are not on OWFS, they are directly wired to an > ancient microcontroller with custom software, which reports and logs _every_ > failed or anomalous reading - once per second to 12 bits, year after year. > Since I added the active pullup and pulldown interface, and Schottky diodes > and TVS protection at each end of the bus, they have been absolutely > bulletproof. > > I'm here because I'd like to duplicate that reliability using modern hardware > with the convenience of swapping a USB plug instead of tinkering with my > jungle of discrete wiring. My first experiment was to hang a couple of 18B20s > off the w1 interface of my BBB with OWFS, and while they are read reliably, > the readings are consistently about 4F and 8F higher than the same chips when > connected to the old controller (where they match my thermocouple thermometer > exactly). So I'm watching for ideas on which USB interface to try... > Hobbyboards seems to be well recommended, but this kind of report makes me > worry. Are you using their USB interface to reach your 18B20s? I guess you > didn't actually say that... > > Loren > > > > > ------------------------------------------------------------------------------ > One dashboard for servers and applications across Physical-Virtual-Cloud > Widest out-of-the-box monitoring support with 50+ applications > Performance metrics, stats and reports that give you Actionable Insights > Deep dive visibility with transaction tracing using APM Insight. > http://ad.doubleclick.net/ddm/clk/290420510;117567292;y > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
