More than 2 Filters Needed

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Anonymous
Not applicable

 Hello PSOC Community!

   

 

   

I have seen the Filter Componet and it seems to have quite a nifty configuration menu for setting two seperate digital filters quite easily, however, I am wondering what are our options if we need more than 2 filters, and adding external capacitaors to the op-amp inputs is not an option.

   

I looked at the DFB data sheet, and it is limited to two seperate input channels, but I was thinking at least using that I could probally come up with some sort of scheme where I would run one set of samples on one channel under one filter, then output the results to main memory, then run the same samples in that same channel under a different filter and output the new results to a different memory location, and repeat the same process for the second channel giving me 4 effective filters.

   

Before I spent to long trying to investigate that path, I was wondering what kind of solutions normally come up for this problem? Speed is definitly a concern for my applicaiton.

   

 

   

Any advice that could be rendered would be greatly appreciated!

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3 Replies
HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

If you have no realtime needs, your suggestion might work. Having the same filter configuration for all channels (or at least the two pairs) will help.

   

The implementation of this solution might be easier with DMA, in that case you can even have it more or less automatically (by doing ping-pong-DMA between two buffers).

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ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

Certainly using the DFB Editor and assembler one could easily imagine

   

multiple IIR or FIR solutions exceeding 2 filter limitations. Basically

   

create from scratch your own DFB.

   

    

   

 

   

          http://www.cypress.com/?docID=46425

   

 

   

Or using Verilog and the MAC in the DFB.

   

 

   

All depends of course on required filter performance and sampling rates

   

associated with filter requirements.

   

 

   

From an analog perspective the TIA has effectivley programmable bandwidth.

   

There are techniques of using the 1 pole comped OpAmp for filtering appications

   

with just resistors. Just google "capacitorless OpAmp Filters".

   

 

   

    

   

          https://www.google.com/search?q=dfb+editor+psoc&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:officia...

   

 

   

Regards, Dana.

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Anonymous
Not applicable

 HLI and Dana,

   

 

   

Sorry for not responding sooner, last week was very hectic for me!

   

My exact timing contstraints have yet to be figured out, but as fast as performance as possible would be desired, so I think I will examine using the DFB as a DSP engine along with some judiciouse use of DMA.

   

 

   

Thanks!

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