2 Replies Latest reply on Aug 20, 2013 5:47 AM by userc_43240

    Filter configuration - alternative input?



      I'm new to the community and to PSoC developing.


      I just have a quick question about a fairly simple project that I am currently up to.


      Plain and simple, I grab a signal from a generator, pass it through ADC, then on to a lowpass filter, DAC and Oscilloscope. No real problems there, I was just wondering if I can run the configurations (be it the filter stages, cutoff frequency etc) without reprogramming. Let's say by sending the parameters through UART, I2C etc.


      Thanks in advance for your time!

        • 1. Re: Filter configuration - alternative input?

          The answer to your question depends on the target device you are thinking of: PSoC1, PSoC3 or 5, you are here in the "pure" software-forum.





          • 2. Re: Filter configuration - alternative input?

            PSOC 1, filters are switch cap, you can modify filter parameters with register writes. However


            the filter response is not a simple write to a single register. You would build an array of


            values for all the caps and clocks, for a given response, and  use that to control config  thru


            register writes. Designer wizard could be used to get values for each desired response.




            PSOC 3/5 different matter. Depends on use of IIR or FIR how you would approach. Right


            now not well documented how to do this. But you can access coefficients of filter to alter


            response. Or use the DFB assembler http://www.cypress.com/?rID=60720 and build from


            the ground up. Note Creator wizard gives you coefficient values to use.




            PSOC 4 has no DMA or DFB, but does have a 32 x 32 multiplier, so if sample rate of filter


            not to high simple FIR or IIR coding for a filter could be done.




                      In closing the DSP approach in PSOC 3/5 probably easier to tune than PSOC 1, but all could


            work depending on your goals.




            Regards, Dana.

            • 3. Re: Filter configuration - alternative input?

               Thank you for your assistance.


              Bob Marlowe, I'm using PSoc 5.




              danaaknight, I'll use an FIR filter. The DFB assembler you're suggesting seems interesting, although it looks like a lot of effort for a relatively simple task as this.