about the PSoC3 DFB

Anonymous · ‎Jan 08, 2010

        Now I create a project

I need use the DFB, but the DFB datasheet write "Only one filter component should be placed in a design. There is nothing to prevent placing two components but the design will not build and work correctly"

my question is I need use more filter about 10.
I don't know the software can allow me to do " Put 10 DFB and use mux to switch everyone DFB"

hey let's think together (Actually I'm anxious.....haha)

Anonymous · ‎Jan 15, 2010

        I'm not sure if I am correctly answering your question, but there is only 1 DFB block in the PSoC 3 architecture. The block can setup more than one filter via channels.

Are you looking for 10 different filter setups, or 10 different signals that might be running thru a similar filter configuration?

Thanks,
Bobby

Anonymous · ‎Jan 15, 2010

        thanks rjo
yes, i'm looking for 10 different filter setups. because my input is audio, so i want to show the 10 band like the players show.

but the DFB in the PSoC3 is only 2 channel !! right?

thanks

Anonymous · ‎Feb 19, 2010

Im also looking and answer for this topic. In the TRM it says you can get many channels but the number of channels depends on DFB memory and programing.... I think the control block of DFB must be programmed using the special Assembler instruction set for this block. Im trying to get this working without success, i join to your question and i hope that the people from cypress who program de DFB Component could help us.

AnuM_41 · ‎Feb 22, 2010

        For your clarification about PSoC3/5 DFB:

1) There is only one DFB block inside PSoC3/5 which can be used to implement one or multiple filters.

2)The DFB block has two 24 bit channels - i.e. two 24 bit staging and holding registers [ Architecture targeted for stereo streaming applications]along with two set of RAMs - RAM A and RAM B each of 24bit *128(depth) .

3) The number of filters that can be implemented using DFB depends on your filter characteristics like type of filter , roll off etc.It is basically limited by the amount of RAM available to store the Filter coefficients and state variables. For eg. in IIR filters - TypeII - each biquad requires 5 RAM locations for storing filter coefficients and 2 RAM locations for storing the state variables. So the total memory requirement is 5*N+2(overhead for storing scaling factors) for storing coefficients and 2*N for storing state variables. Suppose we store filter coefficients in RAM A and state variables in RAM B , the number of biquads that can be implemented using DFB is limited by the coefficient RAM(RAM A = 128 *24bit). Hence the maximum number of biquads that can be implemented using this architecture is 25((25*5+2)<128)

4) Currently we have only one Filter component in PSoC creator which can support the design of only FIR filters with a maximum of 128 filter taps. This FIR filter component supports two channels and upto 4 cascaded filters in a single channel.

5) If you want more filters you might want to go for some custom IIR filter implementations , but this requires some custom components and assembly coding , which is not yet supported in PSoC creator.

Hope you have got your doubts clarified.

Anonymous · ‎Feb 23, 2010

OK!!
thanks guys

Anonymous · ‎Nov 21, 2013

I'm reviving this thread, since I'm trying to implement more than two filters and would like to use the DFB resources. I understand that it is possible to do it, but I'm not quite seeing the path forward. Is there an example that shows the DFB filtering more than two data streams? It would be extremely helpful. Thanks.