Mathematics and remainder for PLL MC145158

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  1. - 21st August 2005, 20:33 #1
    Darrel Taylor's Avatar
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    OOPS, you're right.

    Somehow, in the process of posting it, I lost two 0's in the third DIV32.

    This works better.
    Code:
    <font color="#000000"><b>Freq1      </b><font color="#008000"><b>VAR WORD
</b></font><b>Freq2      </b><font color="#008000"><b>VAR WORD

</b></font><b>N          </b><font color="#008000"><b>VAR WORD
</b></font><b>A          </b><font color="#008000"><b>VAR WORD
</b></font><b>Remainder  </b><font color="#008000"><b>VAR WORD


</b></font><font color="#0000FF"><b><i>; --- Frequency must be split into 2 variables ---
</i></b></font><b>Freq1 </b>= <b>4336   </b><font color="#0000FF"><b><i>; 433687.5
</i></b></font><b>Freq2 </b>= <b>875
</b><font color="#008000"><b>GOSUB </b></font><b>PLL_Calc

</b><font color="#008000"><b>STOP

</b></font><b>PLL_Calc</b>:
    <b>N </b>= (<b>5018 </b>- <b>Freq1</b>)     
    <font color="#008000"><b>IF </b></font><b>Freq2 </b>&gt; <b>0 </b><font 

color="#008000"><b>THEN          
        </b></font><b>A </b>= <b>1000 </b>- <b>Freq2   
        N </b>= <b>N </b>- <b>1      
    </b><font color="#008000"><b>ELSE                       
        </b></font><b>A </b>= <b>0              
    </b><font color="#008000"><b>ENDIF                      
    </b></font><b>N </b>= <b>N </b>* <b>8          
    A </b>= <b>A </b>* <b>8          

    N </b>= <b>N </b>+ (<b>A</b>/<b>1000</b>)       
    <b>A </b>= <b>A </b>- (<b>A</b>/<b>1000</b>*<b>1000</b>)  
        
    <b>N </b>= <b>N</b>*<b>10                   
    N </b>= <font color="#008000"><b>DIV32 </b></font><b>64                   
    Remainder </b>= <b>R2                     
    Remainder </b>= <b>Remainder </b>* <b>10000      
    Remainder </b>= <font color="#008000"><b>DIV32 </b></font><b>64               
    
    A </b>= <b>A </b>* <b>10000              
    A </b>= <font color="#008000"><b>DIV32 </b></font><b>6400       <font color="#0000FF">; <-- Changed, was 64</font>           
    
    A </b>= <b>A </b>+ <b>Remainder
    A </b>= <b>A </b>* <b>64
    A </b>= <font color="#008000"><b>DIV32 </b></font><b>10000
    Remainder </b>= <b>R2
    </b><font color="#008000"><b>IF </b></font><b>Remainder </b>&gt;= <b>5000 </b><font 

color="#008000"><b>THEN </b></font><b>A </b>= <b>A </b>+ <b>1
</b><font color="#008000"><b>RETURN</b></font>
    Last edited by Darrel Taylor; - 22nd August 2005 at 00:10.
    DT
  2. - 22nd August 2005, 11:09 #2
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    Default still not Ok

    Sorry Darrel, can you have a look again ?
    In the code A = (A/1000*1000) does not do anything
    So the A counter value is not calculated correctly


    Is it possible to use for freq1 only the 3 first digits
    for freq2 4 digits, it makes more sense and easyer for the serin2 command
    to enter the completer frequency

    433.6875 Mhz so we can split 433 and 6875 into 2 variables

    What you think ?
  3. - 22nd August 2005, 19:13 #3
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    In the code A = (A/1000*1000) does not do anything
    Yes it does! Since PBP only works with integers, dividing by 1000 then multiplying by 1000 will isolate any digits over 1000. With Freq2 only being 3 digits, anything over 1000 gets added to the N value.


    Is it possible to use for freq1 only the 3 first digits for freq2 4 digits
    No. Due to overflow and accuracy problems, Freq2 must only be 3 digits. Since, the numbers are being parsed from ascii text, it shouldn't matter how many digits are in each parameter.

    Here are some sample results of actually running the routine on a PIC16F877.
    Scroll to the right for the PIC results.
    Code:
    <table BORDER="1" CELLSPACING="0" BORDERCOLOR="#000000" CELLPADDING="2" WIDTH="789" height="279">
  <tr>
    <td WIDTH="11%" HEIGHT="23">
      <p></p>
    </td>
    <td WIDTH="9%" HEIGHT="23">
      <p></p>
    </td>
    <td WIDTH="9%" HEIGHT="23">
      <p></p>
    </td>
    <td WIDTH="3%" HEIGHT="213" rowspan="11">
      <p></p>
    </td>
    <td WIDTH="48%" HEIGHT="23" colspan="5">
      <p ALIGN="CENTER">Calculated</td>
    <td WIDTH="2%" HEIGHT="213" rowspan="11">
      <p>&nbsp;</p>
      <p>&nbsp;</p>
      <p>&nbsp;</p>
      <p>&nbsp;</p>
      <p>&nbsp;</p>
      <p>&nbsp;</p>
    </td>
    <td WIDTH="19%" COLSPAN="2" HEIGHT="23">
      <p ALIGN="CENTER">Results from PIC</td>
  </tr>
  <tr>
    <td WIDTH="11%" align="center" ><b>
      <p >Freq</b></td>
    <td WIDTH="9%" align="center" ><b>
      <p >Freq1</b></td>
    <td WIDTH="9%" align="center" ><b>
      <p >Freq2</b></td>
    <td WIDTH="11%" ><b>
      <p >C Result N</b></td>
    <td WIDTH="8%" ><b>
      <p >INT N</font></b></td>
    <td WIDTH="11%" ><b>
      <p >Remainder</font></b></td>
    <td WIDTH="11%" ><b>
      <p >C Result A</font></b></td>
    <td WIDTH="7%" ><b>
      <p >INT A</font></b></td>
    <td WIDTH="10%" align="center" ><b>
      <p >N</font></b></td>
    <td WIDTH="9%" align="center" ><b>
      <p >&nbsp;A</font></b></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">430000.0</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4300</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">0</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">897.5</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">897</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.5</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">32</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">32</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">897</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">32</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">430816.5</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4308</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">165</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">887.29375</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">887</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.29375</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">18.8</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">19</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">887</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">19</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">431123.3</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4311</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">233</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">883.45875</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">883</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.45875</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">29.36</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">29</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">883</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">29</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">432000.0</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4320</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">0</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">872.5</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">872</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.5</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">32</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">32</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">872</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">32</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">432086.1</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4320</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">861</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">871.42375</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">871</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.42375</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">27.12</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">27</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">871</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">27</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">433010.7</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4330</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">107</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">859.86625</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">859</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.86625</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">55.44</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">55</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">859</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">55</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" ><b>
      <p ALIGN="RIGHT">433687.5</font></b></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4336</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">875</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">851.40625</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">851</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.40625</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">26</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">26</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">851</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">26</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">438214.0</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4382</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">140</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">794.825</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">794</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.825</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">52.8</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">53</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">794</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">53</font></td>
  </tr>
  <tr>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">440000.0</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">4400</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">0</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">772.5</font></td>
    <td WIDTH="8%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">772</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">0.5</font></td>
    <td WIDTH="11%" >
      <p ALIGN="RIGHT">32</font></td>
    <td WIDTH="7%" BGCOLOR="#ffff00" >
      <p ALIGN="RIGHT">32</font></td>
    <td WIDTH="10%" >
      <p ALIGN="RIGHT">772</font></td>
    <td WIDTH="9%" >
      <p ALIGN="RIGHT">32</font></td>
  </tr>
</table>
    The only possibility I can see for getting the wrong answer, is that I am rounding the A value in the last line of the routine. You had only requested the integer. If you don't want it to be rounded, simply comment out the ...

    IF Remainder >= 5000 THEN A = A + 1

    If you still get the wrong numbers, let me know.

    <br>
    Last edited by Darrel Taylor; - 22nd August 2005 at 19:21.
    DT
  4. - 23rd August 2005, 22:00 #4
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    Default oeps

    Hi Darrel

    Oeps, I changed A var word to A var byte to save some place
    But as A is only 127, but you use the word space to calculate

    Thanks again, it looks that it works
  5. - 23rd August 2005, 23:30 #5
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    Just curious where the "R2" comes from?
  6. - 23rd August 2005, 23:53 #6
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    R2 is one of PBP's system variables. They are defined in the PBPPICxx.RAM files, located in the PBP folder.

    In this case R2 holds the modulas (remainder) of the DIV32 command.

    For more info ... http://www.picbasic.co.uk/forum/showthread.php?t=48

    <br>
    DT
  7. - 23rd August 2005, 23:59 #7
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    So this is basically the same as the // but only for DIV32?
  8. - 24th August 2005, 02:02 #8
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    Question

    Quote Originally Posted by Darrel Taylor
    R2 is one of PBP's system variables. They are defined in the PBPPICxx.RAM files, located in the PBP folder.

    In this case R2 holds the modulas (remainder) of the DIV32 command.

    <br>
    I was looking through this file, hoping to learn some of that voodoo that Darrel pops on us time to time... but all the definition said was "System Register". Does anyone know just what exactly these other variables mean or do? Is it documented somewhere that I have missed?
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