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Using the DS1620 Digital Thermometer / Thermostat — Parallax Forums

Using the DS1620 Digital Thermometer / Thermostat

Mike2545Mike2545 Posts: 433
edited 2009-01-07 21:39 in BASIC Stamp
Hi all, First time posting a question. I am experimenting with the DS1620 and found an interesting problem maybe you can help me with. After hooking everything up and running sample program provided by Parallax, I was satisfied with the performance until I discovered it would not calculate 68,70,72,74,& 77 degrees F. There may be more numbers but I gave up running it through the paces. Is this an issue with the conversion from C to F or is it a problem enhanced by Basis Stamps not liking fractions? Any help is appreciated.

Mike2545

Comments

  • Tex4uTex4u Posts: 30
    edited 2009-01-07 03:11
    Hey Mike,

    Post the code and schematic you are using. After the we have a look, it will make everything clearer. I am having no issues with several 1620's I have.

    Thanks

    Tex

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    The more I look for common sense in the world...

    the more·I·find how un-common it is.
    ·
  • Tracy AllenTracy Allen Posts: 6,662
    edited 2009-01-07 08:08
    It probably does have to do with the conversion from whole degrees Celsius to Fahrenheit. There are almost but not quite two degrees F in each degree C.

    The DS1620 can do better. as it does return the temperature to a resolution of about 0.5 degree Maybe the demo program rops the fraction before it converts to Fahrenheit.

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    Tracy Allen
    www.emesystems.com
  • Mike2545Mike2545 Posts: 433
    edited 2009-01-07 12:04
    Tex,
    Here is a copy of the program I am using.
    bs2
    bs2
    TempDS1620BS2.bs2
    2K
  • Beau SchwabeBeau Schwabe Posts: 6,563
    edited 2009-01-07 16:52
    Mike2545,
    What has been suggested as far as the conversion from C to F is indeed what is happening.· Not to add insult to injury, the code that you are using only uses a resolution of 1 Deg C instead of 0.5 Deg C.· This translates to 1.8 Deg F resolution
    Look at the following link on page 161 for a slightly modified version of code that will display the temperature in 0.5 Deg C resolution. (0.9 Deg F)
    http://www.parallax.com/Portals/0/Downloads/docs/books/sw/Web-SW-v2.1.pdf
    ·
    ...There is yet another way to get an even higher resolution out of the DS1620.· Starting on page 168 of the same article, the maximum resolution is 0.0625 Deg C (0.1125 Deg F)
    Since the·article·above was written,·there is no longer a need to read the Slope (or number of Counts per Deg C).· Read here to find out why... http://forums.parallax.com/showthread.php?p=608042
    ·






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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.

    Post Edited (Beau Schwabe (Parallax)) : 1/7/2009 4:58:20 PM GMT
  • Mike2545Mike2545 Posts: 433
    edited 2009-01-07 21:39
    Beau,

    Thanks for the support. I'll re-work my program with this new information.



    Mike2545
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