maybe you should use simultaneous + cached read since it can put all temperatures in cache, while you just read 1 temperature check source code, but i think that's something like it
2011/2/5 Roberto Spadim <[email protected]>: > i didn't read the code about this skip rom command in owfs, but i > think it's just a bit (a file) to change from 0 to 1 > and all new temperatures will be read as simultaneous > the problem is > if owfs just read one file, how could you use this function? you > should read 100 files at once, but it doesn't exists (i think) > > 2011/2/5 Mick Sulley <[email protected]>: >> Yes I have seen the 85 degree situation, it happens sometimes if you run >> in parasitic mode and do not ground the VDD line, but sometimes it seems >> to run happily like that. >> >> I see the reference in the spec sheet to issuing a Skip ROM command, but >> I have no idea how to do that using pyowfs. I guess I need to read a >> bit deeper into basic owfs documentation. >> >> Thanks >> Mick >> >> On Sat, 2011-02-05 at 03:29 +0100, patyrk wrote: >>> Dnia 2011-02-04, pią o godzinie 23:34 -0200, Roberto Spadim pisze: >>> > i never used simultaneous... >>> > but ds18b20 and ds18s20 sometime have a problem (maybe low power or >>> > problem on wire, i never founded why) >>> > it restart internal cpu (ds1820) >>> > and send 85 degree (i don't remember but it's a fixed value) >>> > if you get that value, you need read more two times to get the real value >>> > i think simultaneous read will make it more problematic... >>> >>> Just read the ds18b20 specs and found this (page 11) >>> http://datasheets.maxim-ic.com/en/ds/DS18B20.pdf >>> SKIP ROM [CCh] >>> The master can use this command to address all devices on the bus >>> simultaneously without sending out >>> any ROM code information. For example, the master can make all DS18B20s >>> on the bus perform >>> simultaneous temperature conversions by issuing a Skip ROM command >>> followed by a Convert T [44h] >>> command. >>> >>> So it should be possible to make conversion and the read all >>> scratchpads? Is should be much faster. The specs doesn't mention that >>> ds18b20 can't be in parasite mode. I think that just blocking the bus 1 >>> second will give enough time for conversion to take place. >>> >>> Now I don't see any performance increase when invoking simultaneous >>> before temp. read. >>> >>> -- >>> P4trykx >>> >>> > >>> > >>> > 2011/2/4 patyrk <[email protected]>: >>> > > Dnia 2011-02-05, sob o godzinie 01:10 +0000, Mick Sulley pisze: >>> > >> My sensors are powered, the temperature sensors are a mix of DS18B20 >>> > >> and >>> > >> DS18S20, I just used DS1820 as a generic term. >>> > >> >>> > >> Is there a way to use simultaneous conversion with pyowfs? >>> > > I don't know pyowfs >>> > > but when mounted by owfs there is a >>> > > >>> > > /mnt/owfs/simultaneous/temperature >>> > > >>> > > file and I suspect writing 1 to this file trigers the conversion signal >>> > > >>> > > >>> > > >>> > > -- >>> > > P4trykx >>> > > >>> > > >> >> >> ------------------------------------------------------------------------------ >> The modern datacenter depends on network connectivity to access resources >> and provide services. The best practices for maximizing a physical server's >> connectivity to a physical network are well understood - see how these >> rules translate into the virtual world? >> http://p.sf.net/sfu/oracle-sfdevnlfb >> _______________________________________________ >> Owfs-developers mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/owfs-developers >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > -- Roberto Spadim Spadim Technology / SPAEmpresarial ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
