-----Original Message----- From: <owner-src-committ...@freebsd.org> on behalf of Warner Losh <i...@bsdimp.com> Date: 2016-05-23, Monday at 10:37 To: Justin Hibbits <chmeeed...@gmail.com> Cc: Ravi Pokala <rpok...@mac.com>, src-committers <src-committ...@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, Luiz Otavio O Souza <l...@freebsd.org>, "svn-src-...@freebsd.org" <svn-src-...@freebsd.org> Subject: Re: svn commit: r300421 - in head/sys: arm/allwinner arm/broadcom/bcm2835 arm/freescale/imx arm/mv dev/acpi_support dev/acpica dev/amdtemp dev/coretemp dev/iicbus powerpc/powermac
>On Sun, May 22, 2016 at 1:12 PM, Justin Hibbits <chmeeed...@gmail.com> wrote: >> >> On May 22, 2016 13:51, "Ravi Pokala" <rpok...@mac.com> wrote: >>> >>> Out of morbid curiosity, why do these things report in deciKelvin anyway? >>> Are there sensors we support out there which report native Kelvin, or that >>> report sub-degree precision? >>> >>> Thanks, >>> >>> Ravi (rpokala@) >>> >> >> There are many i2c sensors which report in sub-degree centigrade. Though >> some of them are in 1/8 (or other power of 2) degree precision, not 1/10. > >ACPI reports in decikelvin, and it was the first thing we supported. Some 1 >wire >devices support 1/16th a degree, and we support it in millikelvin since 1/16th >is 0.0625. So the precision needed is actually greater than what we're >reporting. >However, the accuracy of the measurement isn't +/- 0.001, it's closer >to +/1 0.063 >or so (well, that's a relative accuracy, absolute accuracy is closer >to +/- 1 degree). >We report the higher level of precision so that applications that use >the relative >temperature can use it to inform a control loop. We have no good way to report >relative precision for a measurement, or the absolute accuracy. > >Warner Good to know. Thanks guys. -Ravi _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
