lowpass filter

[coradi]

Does anybody have working code(im Beginner) for an lowpass filter?
I need this for my Mikro Pascal Projekt for ADC Measurement

[Zvoni]

https://forum.lazarus.freepascal.org/index.php?topic=15412.0

[dseligo]

https://forum.lazarus.freepascal.org/index.php?topic=15412.0

Link in the post (http://www.antillasoft.com/) doesn't work, user AntillaSoft was last active in 2013.
Maybe someone has copy of components?

[Zvoni]

Did you have a look in OPM?
I'm currently at work, and we've restricted Internet-Access (cannot access OPM-Repo)

EDIT: https://github.com/jakobsche/equalizer

[avra]

Does anybody have working code(im Beginner) for an lowpass filter?

Here is one in MikroC. Shouldn't be too hard to adapt to MikroPascal.
https://libstock.mikroe.com/projects/view/252/digital-low-pass-filtering-or-how-to-add-more-bits-of-resolution-to-an-adc

If simple integrator for smoothing the signal is enough then maybe this will work:

Code: Pascal  [Select][+][-]

1. function SimpleIntegrate(const OldVal, NewVal: float; const factor: byte): float;
2. var
3.   x: float;
4. begin
5.   x := (OldVal * factor) + NewVal;
6.   Result := x / (factor + 1);
7. end;

[Thaddy]

https://www.musicdsp.org/en/latest/Filters/225-delphi-class-implementation-of-the-rbj-filters.html should work.

[Nitorami]

For tasks like smoothing ADC values I would suggest something very simple like

Code: Pascal  [Select][+][-]

1. xout := xout*k + xin*(1-k);
2.  

where xin is the next input value from the ADC and xout is your smoothed output. Just repeat this for each sample from the ADC. 
k is a fixed value in the range 0...1. The closer k is to 1, the slower the output will follow the input.

[avra]

For tasks like smoothing ADC values I would suggest something very simple like

Code: Pascal  [Select][+][-]

1. xout := xout*k + xin*(1-k);

That is just a variation of SimpleIntegrate() function, which was not written as a one liner for the sake of clarity. I prefer SimpleIntegrate() form because it is very clear that if you feed the function with the same NewVal for factor number of iterations, result will reach the value of NewVal.