Not Constant Display???

Discussion in 'Embedded Systems and Microcontrollers' started by dogar sahab, Dec 31, 2008.

  1. dogar sahab

    Thread Starter Active Member

    Mar 15, 2008
    116
    0
    We have made a TEMPERATURE MONITOR PROJECT in which we are using 89C51 microcontroller and LM35 temperature sensor..We are also using ADC 0804...We are going to display this temperature on 7-segment display..
    The problem is that 7-segment display doesnt give a constant reading of the temperature..Suppose if the tempearture is 25C then our display oscillates between 25 then becomes 24 then 26..
    It doesnt give the constant 25C..Is this due to some noise in the analog voltage coming from temperature sensor and if so then how to remove it????
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    It look like there is some noise on the temperature signal.
    How large is the distance between sensor and ADC ?
    You could try to use an RC filter between sensor and ADC.

    Greetings,
    Bertus
     
  3. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    What is the span of your measurement?

    i.e. If ADC0804 output=0, what should be the temperature?

    if ADC0804 output=255, what should be the temperature?
     
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