Q: DS18S20 + Pic

[Chris]

I have a DS18S20 connected to a pic, readings fluctuae on every read ie,
25.01 ,.10, .20, .06 etc, should the reading be stable? is there a way
to stabalise them? i also get the same reactions when reading values
from the ad ports ie 24,26,23,27 steps it doesn't stay too stable even
though the value via a dmm is....

Thanks for any advice

 

[Bob Masta]

On Fri, 06 Aug 2004 19:06:36 -0400, Chris <chrispol@videotron.ca>
wrote:

I have a DS18S20 connected to a pic, readings fluctuae on every read ie,
25.01 ,.10, .20, .06 etc, should the reading be stable? is there a way
to stabalise them? i also get the same reactions when reading values
from the ad ports ie 24,26,23,27 steps it doesn't stay too stable even
though the value via a dmm is....

Thanks for any advice

Without knowing anything about your particular system,
I will point out that DMMs are relatively insensitive to
interference and noise that is synchronous with the
power mains, since they average over an integral number
of powerline cycles. Your A/D may be reading mains
hum at 60 Hz, but asynchronously so that it doesn't hit
the same phase each time. If you can adjust the timing
of your A/D readings to be nearly an integer multiple of the
60 Hz period, see if the variation in readings slows way
down or stops as you get in phase with the line.

Hope this helps!



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com