DS1620 problems

Archiver

I have the DS1620 thermometer IC wired up as shown in the Parallax app note
and am trying their sample code. No matter what I do I always get a
temperature reading of 0 back from chip. I've tried the chip in one shot
and continuous modes with the same results. Reading/writing the
configuration register seems to work OK, but the temperature reading is
always 0.

Any known issues with this chip or suggestions on what I might be doing
wrong?

Thanks,

/* Andrew */
----
Andrew Tucker
Software Engineer
Aegis Software
206-447-4175 x120
mailto:andrewt@a...

Archiver

I use in continue DS1620 in a data logger with parrallax and other code.

From time to time (1 or 2 time a year...), temperature reading drop to 0 and
sure stay to 0 !

The reason ? I have no soldering leads ? Just disconnect 5V for a few time
and then it works fine.

I intend to drive this disconnecting by condition soft... I know it's not the
good way.

Sorry for the bad knowledge of this problem.

Archiver

> I have the DS1620 thermometer IC wired up as shown in the Parallax app
note
> and am trying their sample code. No matter what I do I always get a
> temperature reading of 0 back from chip. I've tried the chip in one shot
> and continuous modes with the same results. Reading/writing the
> configuration register seems to work OK, but the temperature reading is
> always 0.
> Any known issues with this chip or suggestions on what I might be doing
> wrong?
> Thanks,
> /* Andrew */
>----
>Andrew Tucker
>Software Engineer
>Aegis Software
>206-447-4175 x120
>mailto:andrewt@a...

Hi Andrew,

The DS1620 is very sensitive to noise on its power supply, and the effect
is to kick the chip out of the continuous conversion mode. The chip
returns zeros. Be sure you have the bypass capacitor installed. Check the
power supply for oscillations, or for noise from motors etc. You can put
the start-conversion command ($EE) in the main loop _before_ the one second
delay, to continually kick start it.

If you are using single conversion mode, be sure to wait the full one
second after the start conversion before attempting to read the data. The
start conversions command ($EE) _must_ be placed in the main loop _before_
the one second delay.

For more info on the DS1620, you can refer to the Stamps-in-class Earth
Measurements unit number 1. Also on my web site at
<http://www.emesystems.com/OWL2face.htm#DS1620-HR> there is some
information on using the DS1620 in its high resolution mode (reading to
0.01 degree C) and on using its standalone thermostat mode.

-- Tracy Allen
Electronically Monitored Ecosystems
http://www.emesystems.com