>> A: is there a way to force new acquisition with each request? > > if you do a "ls /mnt/1wire" you see a couple of special directories. One > is named "uncached". That should be evocative enough ...
I've only been playing with owfs for about two days: I hadn't yet found 'uncached' in the documentation. That sounds like it'll do what I need. Having a cache system for concurrent access is a very cool idea. >> B: would +5V external rather than parasitic powered DS help? > > Well, somewhat. The point is that if you use external power the > converter will tell the host when it's done. Otherwise you have to > wait however long a pessimistic estimate of the conversion time is. > > My own measurements were measurably different (and more jittery) with > parasitic power, so I decided not to use it anywhere if possible. > (Some of these devices manage not to *have* a +5V input...) Interesting. Well, +5V it is, then. > The question is, how fast does your input change, so that you need the > quick updates to make your algorithm behave correctly? That's something I'm trying to figure out right now. Obviously a furnace full of molten glass is going to be seeing degree-per-hour changes at max, but an annealing oven has a door covering one whole side open every five minutes, with drops of fifty degrees per second or so. What I'd like is to find the limits of the system and do what I can with those, and that'll let me decide which hardware I can keep using and which needs to be upgraded. I built a fancy megahertz-capable dedicated thermocouple amplifier and A/D converter but it's a pain to debug and develop for, whereas OWFS is quick, so until I have all my other problems hammered into shape, OWFS is great for prototyping. >> The software is C; I'm using fopen and fscanf to >> acquire the contents of /mnt/.../temperature and work with the results. > > You might want to use one of the provided libraries instead. > It's much faster and depends on fewer pieces of software you might not > really need, or want, in a production environment. This will never be production-worthy: it's purely for my own projects. With that said, I'll look into the provided libraries. All I really need, though, is the temp value, so reading the text file containing it seems pretty straightforward, though I'm always open to better ways of doing things. I apologize for taking up time on a development list, for applications questions, but appreciate the advice from both respondents. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
