4 Replies Latest reply on Feb 16, 2016 10:34 AM by rogac_1123691

    DFB and real time audio filtering?

              So i am familiar with the psoc4 and I have just got a PSoC5 i am really excited about the DFB although there does not seem so be a whole lot of info out there and examples using it. I am totally new to DSP, i want to make sure the PSoC is capable of doing what I need before I dive in to learning how to use the DFB assembler. I would like to use a PSoC5 to make a phono preamp. For those who dont know when you play a record back you have to EQ the sound and lp filter at 50hz 200hz and 22khz. I belive those are the right frequencys.. if one were to google riaa curve you can see the what the filter should look like. Im wondering if the psoc can handle this kind of filtering at 16 and 24 bits? If so what is the advantage of doing this with the DFB? Hitting that curve correctly with standard size components even with great tolerance can be a pita do to temp co drift and johnson noise. Will switching from passive/active analog filters to DSP keep a stable filter with out anything to SNR or attenuating the signal? Currently im doing all this with passives and opamps. I would like to design a higher end product and if i can pack all the parts for digital control and analog filtering/amplification on one chip that would be awesome, especially if DSP will help with drift and noise! My thinking could be totally wrong too... but like i said idk much about DSP and want to choose the right tool for the job!   
        • 1. Re: DFB and real time audio filtering?

          Welcome in the forum!


          The DFB assembler is a pain in the a..!  What can be used quite well and with good performance is the filter component. When you are able to define some filters (not more than 4) which when chained will fit your RIAA you're fine off. You will just have to set the filter parameters.
           It will be somewhat complicated to change the filter on-the-fly for equalizing etc.


          The real problem for your audio occurs at the end of the filtering: What are you going to do with your digital data stream? converting to analog with an 8 bit DAC? Lol (Lots of losses). There are quite more sophisticated DSP chips that will do that job better than a PSoC.





          • 2. Re: DFB and real time audio filtering?
                    Thank you :) Well in that case it would be perfectly fine to just use an external dac, wouldnt it? I was also hoping maybe you could explain to me the performance difference between analog and dsp?   
            • 3. Re: DFB and real time audio filtering?

              Sorry, I'm a digital man, so no comparisons with analog performances. The external DAC would help. To maintain the high speed you probably will need DMA.





              • 4. Re: DFB and real time audio filtering?

                Im using the PSoC5 proto kit, that is nuts.... I originally got it to do some SDR work with the ADC and DFB.... I never paid attention to the DAC specs!! I can't believe it only has an 8 bit DAC, most everything else built in to the PSoC5 would be somewhat higher priced parts if they were bought as discrete components, the DAC is pretty jelly bean though.