6 Replies Latest reply on Sep 21, 2015 6:03 PM by scott.carlson

    Compensating for Two's Compliment input for DFB Fitler

    scott.carlson

      Hi all,

         

       

         

      I'm using the DFB filter block which takes in data as two's compliment values.  To compensate for this I have offset my original data so it is all positive.  I am transferring all the data via DMAs in and out of the filter to a buffer in SRAM.  I was wondering if there is any way other than manually using the cpu to de offset the data again so it is both positive and negative?

         

      or rather and more preferred, a way to get the data into and out of the filter as negative values either by some trick with the filter or a way to convert the adc data into 2's compliment?

         

       I am going to analyzing the fft so I would rather not have a giant spike right at the beginning.

         

       

         

      I was thinking of the possibility of using udbs (if even possible) or configuring a specialized data path, as I know that would probably work, but I have not created my own datapath yet and I know that can quickly get very hairy, and I don't have much of an idea where I would start.  But I'm more than willing to learn if that's the only option.

         

       

         

      If you frequent these forums, you probably remember at least one of my previous questions since they are all similar to each other.  I AM making substantial progress on my project, and I do spend quite a bit of time reading through the ANs and troubleshooting my code. 

         

       

         

      All your help is/has been greatly appreciated.

         

       

         

      -scarlson