Hello,

excuse-me to disturb you, but I am working on a system to manage the
temperature of  a CCD camera (Audine), but we have a problem with the
DS1820 sensor.
We read the temperature (in fact 8 bytes), next the CRC byte. But 10% of
the time the CRC is bad. It's seem that a bit is read as 1, but it must
be read as 0. We have a pull-up resistor of 4.7k between the +5v and the
data line. We have made test with a PIC controller and we have used two
different compiler (picc and pic-basic). I have also tried to weld the
sensor just on the pins of the pic to avoid distorsion (but the problem
is the same).
So this problem is not the most important, because when we have a bad
CRC, we read again. But after a while (between 5min and 1 hour),  the
temperature send is allways the same, the CRC is OK, but we know that
it's not the good temperature, for example 40C with ice on the CCD chip!!!
If you have an idea, tell it to me.

Thank you

Best regards

Michel Meunier

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu