Hi Paul, On 08/11/2011 07:12 PM, Paul Alfille wrote:
> On Thu, Aug 11, 2011 at 4:27 PM, Pascal Baerten > <[email protected] <mailto:[email protected]>> wrote: > > > However, even if you reach the same timing, you may exceed your > 250ms requirement if you read successively the four devices. > To solve this, the next step is to explicitly force a simultaneous > conversion on the four _powered _devices and simply read the > _cached_ temperatures. > We have however to clarify with Paul if the simultaneous is able to > explicitly trigger the fasttemp? > > > simulteous triggers a "conversion" (temperature measurement) at whatever > resolution was previously set on each sensor. However owfs must lock out > the next temperature reading until the conversion is done. I currently > lock out for the full 1 second as the safest strategy, although I > suppose the lockout could be for the minimum needed by that device and > resolution. It just takes more logic. When not under parasite power (a prerequisite for simultaneous conversion), the DS18B20 will send 0s while it is converting temperature. Based on your comment I understand that the code does not use this feature. Is this correct? Don't know if the other 18x20's behave this way but I noticed the 18B20 behavior when reading its datasheet. Cheers, Eloy Paris.- > > Reading /uncached ignores a simultaneous conversion and forces new > measurement. > > Paul > ------------------------------------------------------------------------------ Get a FREE DOWNLOAD! and learn more about uberSVN rich system, user administration capabilities and model configuration. Take the hassle out of deploying and managing Subversion and the tools developers use with it. http://p.sf.net/sfu/wandisco-dev2dev _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
