Temperature with the LM34C

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  1. - 29th May 2009, 00:04 #1
    aratti's Avatar
    aratti
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    I don't know if I need to do this or not, but I have the VSS and VDD pins tied together, respectively.
    Dave, Vss is the ground or (zero volts) and Vdd is power or (+5Volts), from what you say it seems you have a short.

    Remove it and re-establish the corrected connections.

    Al.
    All progress began with an idea
  2. - 29th May 2009, 00:07 #2
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    There is no short. There are two VVS pins and two VDD pins. They are tied together respectively. In other words, the VVS pins are tied to each other; the VDD pins are also tied to each other.

    ~ Dave
    Last edited by StoneColdFuzzy; - 29th May 2009 at 00:09.
  3. - 29th May 2009, 07:04 #3
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    mackrackit
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    I had to set this up myself to find the problem.

    When you use "DEFINE" everything has to be upper case. It would not work until I made that change. Problem was so simple but hard to see.
    Code:
    <html>
<body><!--StartFragment--><pre><code><font color="#000000">    <font color="#FF0000">DEFINE </font><font color="#0000FF">OSC </font>20
    @ <font color="#0000FF"><b>__config _HS_OSC </b></font>&amp; <font color="#0000FF"><b>_WDT_ON </b></font>&amp; <font color="#0000FF"><b>_LVP_OFF </b></font>&amp; <font color="#0000FF"><b>_CP_OFF
    </b></font><font color="#000080"><i>'DEFINE loader_used 1    ' Boot loader is being used
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>DEBUG_MODE  </b></font>1    <font color="#000080"><i>' Debug sending INVERTED serial data
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>DEBUG_REG PORTC  </b></font><font color="#000080"><i>' Debug Port = PortC
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>DEBUG_BIT </b></font>6      <font color="#000080"><i>' Debug.bit = PortC.6
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>DEBUG_BAUD </b></font>9600  <font color="#000080"><i>' Default baud rate = 9600
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>ADC_BITS </b></font>8       <font color="#000080"><i>' Set A/D for 8-bit operation
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>ADC_CLOCK </b></font>1      <font color="#000080"><i>' Set A/D clock Fosc/8
    </i></font><font color="#FF0000"><b>DEFINE </b></font><font color="#0000FF"><b>ADC_SAMPLEUS </b></font>50  <font color="#000080"><i>' Set A/D sampling time @ 50 uS
    </i></font><font color="#0000FF"><b>samples </b></font><font color="#FF0000"><b>VAR WORD        </b></font><font color="#000080"><i>' Multiple A/D sample accumulator
    </i></font><font color="#0000FF"><b>sample  </b></font><font color="#FF0000"><b>VAR BYTE        </b></font><font color="#000080"><i>' Holds number of samples to take
    </i></font><font color="#0000FF"><b>temp    </b></font><font color="#FF0000"><b>VAR BYTE        </b></font><font color="#000080"><i>' Temperature storage
    </i></font><font color="#0000FF"><b>samples </b></font>= 0             <font color="#000080"><i>' Clear samples accumulator on power-up

    </i></font><font color="#0000FF"><b>TRISA </b></font>= %11111111   <font color="#000080"><i>' Set PORTA to all input
    </i></font><font color="#0000FF"><b>ADCON1 </b></font>= %00000011  <font color="#000080"><i>' Set PORTA.0,1,2,5 = A/D, PortA.3 = +Vref
    </i></font><font color="#FF0000"><b>PAUSE </b></font>500           <font color="#000080"><i>' Wait .5 second

    </i></font><font color="#0000FF"><b>loop</b></font>:
    <font color="#FF0000"><b>FOR </b></font><font color="#0000FF"><b>sample </b></font>= 1 <font color="#FF0000"><b>TO </b></font>20    <font color="#000080"><i>' Take 20 samples
        </i></font><font color="#FF0000"><b>ADCIN </b></font>0, <font color="#0000FF"><b>temp       </b></font><font color="#000080"><i>' Read channel 0 into temp variable
        </i></font><font color="#0000FF"><b>samples </b></font>= <font color="#0000FF"><b>samples </b></font>+ <font color="#0000FF"><b>temp </b></font><font color="#000080"><i>' Accumulate 20 samples
        </i></font><font color="#FF0000"><b>PAUSE </b></font>250           <font color="#000080"><i>' Wait approximately 1/4 seconds per loop
    </i></font><font color="#FF0000"><b>NEXT </b></font><font color="#0000FF"><b>sample
    temp </b></font>= <font color="#0000FF"><b>samples</b></font>/20
    <font color="#FF0000"><b>DEBUG </b></font><font color="#00FF00"><b><i>&quot;Temperature is: &quot;</i></b></font>,<font color="#FF0000"><b>DEC </b></font><font color="#0000FF"><b>temp</b></font>,<font color="#00FF00"><b><i>&quot; Deg F&quot;</i></b></font>,10,13
    <font color="#0000FF"><b>samples </b></font>= 0             <font color="#000080"><i>' Clear old sample accumulator
    </i></font><font color="#FF0000"><b>GOTO </b></font><font color="#0000FF"><b>loop               </b></font><font color="#000080"><i>' Do it forever
    </i></font><font color="#FF0000"><b>END
</b></font></code></pre><!--EndFragment--></body>
</html>
    Last edited by mackrackit; - 29th May 2009 at 07:11.
    Dave
    Always wear safety glasses while programming.
  4. - 29th May 2009, 11:29 #4
    Darrel Taylor's Avatar
    Darrel Taylor
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    Quote Originally Posted by mackrackit View Post
    When you use "DEFINE" everything has to be upper case.
    That's only true when using MPASM.
    Since Bruce's program had @ device, the program was written for PM.exe, and is therefore not case sensitive.

    Frankly, looking for a problem with one of Bruce's programs seems futile.

    There's something wrong with the hardware. Connected to the wrong pins, grounds not connected across the breadboard, etc.
    <br>
    DT
  5. - 29th May 2009, 14:48 #5
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    Quote Originally Posted by Darrel Taylor View Post
    That's only true when using MPASM.
    Since Bruce's program had @ device, the program was written for PM.exe, and is therefore not case sensitive.
    Bruce did not have @ anything, but the OP did. So yes, the OP must be using PM.
    Frankly, looking for a problem with one of Bruce's programs seems futile.
    Agreed!!! I was just trying to find something obvious that the OP could be doing and thought I did.
    There's something wrong with the hardware. Connected to the wrong pins, grounds not connected across the breadboard, etc.
    <br>
    Must be.
    Dave
    Always wear safety glasses while programming.
  6. - 29th May 2009, 15:06 #6
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    I didn't think that I changed Bruce's code, except for direct serial, but it's good to get more than one set of eyes on it. I'll keep checking connections; it's got to be the hardware. Thanks again y'all!

    ~ Dave
  7. - 29th May 2009, 15:39 #7
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    Dave,

    Are you getting anything from DEBUG, or is it just not showing any change in temp?

    If DEBUG is showing a fixed value even when the temp changes, the sensor may be wired
    wrong.

    If you're using a boot-loader;

    1. It most likely has the USART enabled, so you may need to disable the USART to use the
    USART TX pin with DEBUG.

    2. If your serial connection is through a MAX232 inverter, then you need to use mode 0
    with DEBUG for non-inverted serial.

    3. Most boot-loaders don't allow you to change config settings, so embedding them in your
    code isn't necessary. And the loader might have some config settings different than what
    you expect.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com
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