Linear to S Curve conversion

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  1. - 20th May 2007, 11:10 #1
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    luminas
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    Wow, this is more than what I expected from the forum. Great !

    Darrel: You are right, first problem is solved with the negative sine things,

    now the question is" how to adjust the " hardness " of the curve


    Alain: The purpose of this curve is to compensate the output of a joystick to suit players response in a game.

    Some player like "agrresive" joystick response while some other like "standard,linear" response.

    Jon
  2. - 20th May 2007, 11:31 #2
    mat janssen's Avatar
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    Gain!
    x-aSIN(B)
    a is the gain.
  3. - 20th May 2007, 23:55 #3
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    Quote Originally Posted by mat janssen View Post
    Gain!
    x-aSIN(B)
    a is the gain.
    Yup again,

    But, PBP will have problems trying to multiply the negative values from the SIN function.
    So you'll need to remove the sign before multiplying.

    Been playing with it here. I think this program might do what you want Jon.

    It's only for 1 axis, but it should get you started. There are 3 POT's in this example. AN0 is the axis input, AN1 is the Gain setting, and AN2 is a Trim setting. 10-turn 10K pots should be good for the Gain and Trim.

    It uses HSEROUT to display the results in Hyperterminal.
    Code:
    <code><font color="#008000"><b>DEFINE </b></font><b>ADC_BITS </b><font color="#800000"><b>10
</b></font><b>ADCON1</b>.<font color="#800000"><b>7 </b></font>= <font color="#800000"><b>1        </b></font><font color="#0000FF"><b><i>; Right Justify
;ADCON2.7 = 1        ; 18F4550

</i></b></font><b>NEG      </b><font color="#008000"><b>VAR BIT
</b></font><b>Temp     </b><font color="#008000"><b>VAR BYTE
</b></font><b>Result   </b><font color="#008000"><b>VAR WORD
</b></font><b>Xaxis    </b><font color="#008000"><b>VAR WORD
</b></font><b>Xgain    </b><font color="#008000"><b>VAR WORD
</b></font><b>Xtrim    </b><font color="#008000"><b>VAR WORD
</b></font><b>ADvalue  </b><font color="#008000"><b>VAR WORD
</b></font><b>GainAvg  </b><font color="#008000"><b>VAR WORD
</b></font><b>TrimAvg  </b><font color="#008000"><b>VAR WORD
</b></font><b>Avg      </b><font color="#008000"><b>VAR WORD
</b></font><b>AvgCount </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>16
</b></font><b>spread   </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>50

</b></font><b>Main</b>:
    <font color="#008000"><b>ADCIN  </b></font><font color="#800000"><b>0</b></font>, <b>Xaxis               </b><font color="#0000FF"><b><i>; Axis input is not averaged
   
    </i></b></font><font color="#008000"><b>ADCIN  </b></font><font color="#800000"><b>1</b></font>, <b>ADvalue             </b><font color="#0000FF"><b><i>; 0 = no gain, 1023 = gain 3.98
    </i></b></font><b>Avg </b>= <b>GainAvg </b>: <font color="#008000"><b>GOSUB </b></font><b>Average </b><font color="#0000FF"><b><i>; Gain is averaged to stabilize it's value
    </i></b></font><b>Xgain </b>= <b>Avg   </b>: <b>GainAvg </b>= <b>Avg
    
    </b><font color="#008000"><b>ADCIN  </b></font><font color="#800000"><b>2</b></font>, <b>ADvalue             </b><font color="#0000FF"><b><i>; 0 = adjust center -127, 1023 = adjust +128
    </i></b></font><b>Avg </b>= <b>TrimAvg </b>: <font color="#008000"><b>GOSUB </b></font><b>Average </b><font color="#0000FF"><b><i>; Trim is averaged to stabilize it's value
    </i></b></font><b>Xtrim </b>= <b>Avg   </b>: <b>TrimAvg </b>= <b>Avg
    
</b><font color="#0000FF"><b><i>;--- Add Sine and Trim to the Xaxis input ------------------------------------
    </i></b></font><b>Temp </b>= <font color="#008000"><b>SIN</b></font>(<b>Xaxis</b>&gt;&gt;<font color="#800000"><b>2</b></font>)
    <b>NEG </b>= <b>Temp</b>.<font color="#800000"><b>7
    </b></font><b>Result </b>= <font color="#008000"><b>ABS</b></font>(<b>Temp</b>) */ <b>Xgain
    </b><font color="#008000"><b>IF </b></font><b>NEG </b><font color="#008000"><b>THEN </b></font><b>Result </b>= -<b>Result
    Result </b>= <b>Xaxis </b>+ <b>Result </b>+ (<b>Xtrim </b>&gt;&gt; <font color="#800000"><b>2 </b></font>- <font color="#800000"><b>127</b></font>)

<font color="#0000FF"><b><i>;--- Display the results in HyperTerminal ------------------------------------
    </i></b></font><font color="#008000"><b>HSEROUT </b></font>[<font color="#800000"><b>27</b></font>,<font color="#FF0000">&quot;[H&quot;</font>,<font color="#FF0000">&quot;Xaxis = &quot;</font>,<font color="#008000"><b>DEC </b></font><b>Xaxis</b>,<font color="#FF0000">&quot;    &quot;</font>,<font color="#800000"><b>13</b></font>,<font color="#800000"><b>10</b></font>, <b>_
      </b><font color="#FF0000">&quot;Xgain = &quot;</font>,<font color="#008000"><b>DEC </b></font><b>Xgain</b>&gt;&gt;<font color="#800000"><b>8</b></font>,<font color="#FF0000">&quot;.&quot;</font>,<font color="#008000"><b>DEC2 </b></font>((<b>Xgain </b>&amp; <font color="#800000"><b>$0FF</b></font>) */ <font color="#800000"><b>100</b></font>),<font color="#FF0000">&quot;    &quot;</font>,<font color="#800000"><b>13</b></font>,<font color="#800000"><b>10</b></font>, <b>_
      </b><font color="#FF0000">&quot;Xtrim = &quot;</font>,<font color="#008000"><b>SDEC </b></font>(<b>Xtrim </b>&gt;&gt; <font color="#800000"><b>2 </b></font>- <font color="#800000"><b>127</b></font>),<font color="#FF0000">&quot;    &quot;</font>,<font color="#800000"><b>13</b></font>,<font color="#800000"><b>10</b></font>, <b>_
      </b><font color="#FF0000">&quot;Result= &quot;</font>,<font color="#008000"><b>SDEC </b></font><b>Result</b>,<font color="#FF0000">&quot;    &quot;</font>,<font color="#800000"><b>13</b></font>,<font color="#800000"><b>10</b></font>]
     
    <font color="#008000"><b>PAUSE </b></font><font color="#800000"><b>100
</b></font><font color="#008000"><b>GOTO </b></font><b>Main

</b><font color="#0000FF"><b><i>' -=-=-=-=-=-=  Average Analog values -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
</i></b></font><b>Average</b>:    <font color="#0000FF"><b><i>' Smooth data
    </i></b></font><font color="#008000"><b>IF ABS </b></font>(<b>ADvalue </b>- <b>Avg</b>) &gt; <b>spread </b><font color="#008000"><b>THEN
        </b></font><b>Avg </b>= <b>ADvalue
    </b><font color="#008000"><b>ELSE
        </b></font><b>Avg </b>= (<b>Avg</b>*(<b>AvgCount</b>-<font color="#800000"><b>1</b></font>)+<b>ADvalue</b>)/<b>AvgCount 
    </b><font color="#008000"><b>ENDIF
RETURN

</b></font>
    The output in Hyperterminal should look like this ... (in real time)



    HTH,
    DT
  4. - 20th May 2007, 13:06 #4
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    Quote Originally Posted by luminas View Post
    The purpose of this curve is to compensate the output of a joystick to suit players response in a game. Some player like "agrresive" joystick response while some other like "standard,linear" response.
    I'm a bit puzzled by that - wondering if you could explain further?
  5. - 20th May 2007, 13:39 #5
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    Trent ...

    That's just to give a so called " exponential " response to the Joystick :

    smooth ( reduced output / stick displacement ) in the center region and give full output for full stick displacement ...

    so, the gain depends on the input variable value ... to use intellectual language.

    Modellers use that feature most of time ...

    Alain
    Last edited by Acetronics2; - 20th May 2007 at 13:43.
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************
  6. - 20th May 2007, 14:07 #6
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    I see. I think a lot of games now rely on non-proportional digital. Guess in this domain there's not a lot that can be done to tweak things. All arcade games use digital.
  7. - 21st May 2007, 01:50 #7
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    Quote Originally Posted by Acetronics View Post
    Modellers use that feature most of time ...
    Alain
    MOST?
    Heck, I use it ALL of the time...makes me look like a better pilot!
    I only wish that the full size light aircraft had the same type of setup, might make some of my landings look a bit better
  8. - 21st May 2007, 02:03 #8
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    Hey!

    We're trying to help somebody out here.

    You two(3) want to chit chat. Start another thread.
    <br>
    Last edited by Darrel Taylor; - 21st May 2007 at 02:19. Reason: We're - not I'm
    DT
  9. - 21st May 2007, 04:37 #9
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    Thanks Darrel,

    The code is working now

    After experimenting, I am still confused how to adjust the x axis width, independently to left and to right from the center

    The real problem is that the stick (mechanical ) stroke is not identical, say to left 30 degree, to right 26 degree
    but electrically they are centered [ at 50k on 100k stick ]
    this will make our curve response not equal


    If we can adjust the most left / right position, then we can have nice curve, which has true equal left / right width


    Jon
  10. - 21st May 2007, 05:00 #10
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    That's what I was trying to do with the Trim.

    It allows you to adjust the "Center" position of the Control.

    I'm just using pots on a breadboard here, maybe it's not doing it right on the real thing.

    Can you give me any numbers?
    <br>
    DT
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