I am using a DS18B20, with Bruce Reynolds program, a 18f14k22 running at 16 mhz internal osc.

I notice that when the temperature "changes direction", in other words, when it first starts to increase or decrease, the first reading of the DS18B20 does not change. After that it works fine, updates each time a new read takes place.

I noticed this a couple of years ago, and disregarded it, because it was more of a nuisance than anything. However, now I want to detect the temperature change immediately.

To definitely confirm this, I placed a short delay (say 5 seconds or so) following the "Start_Convert" line, to allow warming or cooling the DS18B20. To indicate the delay I simply used a LED, which is turned on for that time, and then briefly turned turned off ( 1 second) after the Convert_Temp subroutine return, prior to the GOTO back to Start_convert.

I tried using a different MODE number on the OWIN, either a 0 or 1 for the reset pulse, with no change.

This seems to be some weird characteristic of the DS18B20 -

Anyone else experienced this ?

Ken