topic GDFLIB IIR Fuction confusion in Digital Signal Controllers https://community.nxp.com/t5/Digital-Signal-Controllers/GDFLIB-IIR-Fuction-confusion/m-p/687094#M1075 <HTML><HEAD></HEAD><BODY><P>The User Reference Manual of the 'General Digital Filters Library'(which is available here [<A href="http://www.nxp.com/assets/documents/data/en/user-guides/56800Ex_GDFLIB.pdf">http://www.nxp.com/assets/documents/data/en/user-guides/56800Ex_GDFLIB.pdf</A>]) has functions to implement IIR Filters. But on Page 3-19, it says that the filter coefficients are calculated using Butterworth Approximation.Does this mean that we can only use Butterworth Filter? Also, as per my knowledge, we have to give the coefficients and therefore other filters can also be implemented.</P><P><span class="lia-inline-image-display-wrapper" image-alt="Capture.JPG"><img src="https://community.nxp.com/t5/image/serverpage/image-id/21581iBAB1839819E23FDE/image-size/large?v=v2&amp;px=999" role="button" title="Capture.JPG" alt="Capture.JPG" /></span></P><P></P><P>Can someone please clear this confusion!</P><P><SPAN style="color: #434648; background-color: #ffffff;">What exactly does the function do? Can I implement a Elliptic filter using this function or not? If not, then what should I do use Elliptic filter?#</SPAN></P></BODY></HTML> Wed, 14 Jun 2017 12:55:24 GMT ritikmadan 2017-06-14T12:55:24Z GDFLIB IIR Fuction confusion https://community.nxp.com/t5/Digital-Signal-Controllers/GDFLIB-IIR-Fuction-confusion/m-p/687094#M1075 <HTML><HEAD></HEAD><BODY><P>The User Reference Manual of the 'General Digital Filters Library'(which is available here [<A href="http://www.nxp.com/assets/documents/data/en/user-guides/56800Ex_GDFLIB.pdf">http://www.nxp.com/assets/documents/data/en/user-guides/56800Ex_GDFLIB.pdf</A>]) has functions to implement IIR Filters. But on Page 3-19, it says that the filter coefficients are calculated using Butterworth Approximation.Does this mean that we can only use Butterworth Filter? Also, as per my knowledge, we have to give the coefficients and therefore other filters can also be implemented.</P><P><span class="lia-inline-image-display-wrapper" image-alt="Capture.JPG"><img src="https://community.nxp.com/t5/image/serverpage/image-id/21581iBAB1839819E23FDE/image-size/large?v=v2&amp;px=999" role="button" title="Capture.JPG" alt="Capture.JPG" /></span></P><P></P><P>Can someone please clear this confusion!</P><P><SPAN style="color: #434648; background-color: #ffffff;">What exactly does the function do? Can I implement a Elliptic filter using this function or not? If not, then what should I do use Elliptic filter?#</SPAN></P></BODY></HTML> Wed, 14 Jun 2017 12:55:24 GMT https://community.nxp.com/t5/Digital-Signal-Controllers/GDFLIB-IIR-Fuction-confusion/m-p/687094#M1075 ritikmadan 2017-06-14T12:55:24Z Re: GDFLIB IIR Fuction confusion https://community.nxp.com/t5/Digital-Signal-Controllers/GDFLIB-IIR-Fuction-confusion/m-p/687095#M1076 <HTML><HEAD></HEAD><BODY><P>Hi, Ritik,</P><P>I think the words "Butterworth" is confused. As you know the DSC only care about filter coefficents, it does not care about how you get the coefficents. of course, you can use <SPAN style="color: #434648; background-color: #ffffff;"> Elliptic</SPAN>, Butterworth, Chebyshev filter，Bessel filter to get the coefficents and use DSC to implement the digital filtering.</P><P>Hope it can help you</P><P>BR</P><P>Xiangjun Rong</P></BODY></HTML> Thu, 15 Jun 2017 07:01:43 GMT https://community.nxp.com/t5/Digital-Signal-Controllers/GDFLIB-IIR-Fuction-confusion/m-p/687095#M1076 xiangjun_rong 2017-06-15T07:01:43Z