FIR lowpass Filter on FPGA

[Slev1n]

Hey guys,

I have the DFD Toolkit and already builded some  fir lowpass filters.I have a Samplerate of 50kHz and I decimate it with a CIC filter with changeable decimation rate. After the CIC filter I need a high roll-off for the FIR low pass filter because I only want my DC signal. As I can vary my decimation rate, the sampling rate of my FIR filter also changes.

The problem is, that the filter coefficients cant be changed on the run like the IIR Butterworth-Filter function which labview has implemented in the math section of the fpga function palette.

Are there examples how to build such FIR filters where I can change the coefficients on the run?

Do you think its possible to build a FIR lowpass with the DFD toolkit and just change the array with the coef. to a control? Than I could change them on the run...

Greetz

Slev1n

[msind · Accepted solution]

Hi Slev1n,

just found this in the Community, maybe this could help you already:

Polyphase Interpolation FIR Filter on FPGA with DFD and Coregen

https://decibel.ni.com/content/docs/DOC-16650

greetings

Michael

[Slev1n]

Hey,

thank you for the link. I havent checked the xilinx core generater yet. I will try if the coefficients are changeable on the run. But as I can see from your link its possible to save up to 256 sets of coefficients.

Thanks for the link!

Slev1n

[msind]

No problem Stev1n,

glad that I could help 😉