1 wire Temp sensor


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  1. #1
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    PortlandJohn Guest

    Red face 1 wire Temp sensor

    I am trying to use a DS1821 1-wire temperature sensor with a 16F877a. Using the OWIN and OWOUT commands I can see the signals going out on my scope but the sensor does not respond.
    Has anyone got any good ideas or working code samples.

    Thanks

    John

  2. #2


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    I've played with the 18B20 and the 18S20 with great success. I'm not too sure about the 18S21 though. I think it is the same type of sensor as the 18S20 but with less accuracy.

  3. #3
    Join Date
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    John,

    could you post your schematic?

    The problem is most likely a missing (or incorrect) resistor.
    If you want to run the Sensor on "parasitic power" have close look at the datasheet regarding the timing.

    BTW
    I'm sure there are already several code examples on this forum.
    regards

    Ralph

    _______________________________________________
    There are only 10 types of people:
    Those who understand binary, and those who don't ...
    _______________________________________________



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