60 Hz Notch filter design

[od805]

Hi,

I am running into this error for a 60 Hz notch filter and idk why: 

Possible reason(s):

Digital Filter Design Toolkit: To design a filter by using the Q factor, you must specify the center frequency value f0 in the range (0, fn), where fn is the Nyquist frequency. If you want to design a filter with the center frequency at DC, choose the By Bandwidth instance.

I don't understand why it won't let me use 40 and 80 for f0 and fs when my sampling frequency from the bandpass is 256 Hz (Nyquist of 128). Can anyone explain how to maneuver this error? And if I'm setting up this notch correctly? Picture and VI attached. Thanks!

[billko]

Is there a reason you are trying to handle this in software, instead of handling it in the circuit design?

[od805]

I'm using an arduino coupled with an EEG click so I'd rather handle this in software. 

mikroe.com/eeg-click

[od805]

Hi,

For the life of me I can't figure out why I'm getting these errors with my filter I've created. I'm reading an analog signal from my arduino and putting them through a series of filters for EEG analysis. First of all, why do these filter settings reset? Every time I STOP the code and click on the filter VI the parameters have reset to their initial state. What the heck? Second I keep getting one of two errors: 

1.  (-24021) Digital Filter Design Toolkit: You must specify frequency values that are greater than zero and less than the Nyquist frequency.

2. 

−24101

The center frequency f0 must be greater than or equal to 0 and less than the Nyquist frequency.

I don't why these errors are happening more so because I don't know how to determine the frequency I'm sampling at. I'm using a for loop of 500 iterations (ie 500 data points approx) and auto indexing this array to feed into the filters to get an output. Regardless, I can't figure out how to fix these errors. Can somebody please take a look at my VI. It's attached and picture below. It has become frustrating. Thanks so much. 

Sincerely,

Omeed

[od805]

Well GerdW merged this post with another of one mine. Hopefully it doesn't lose the ability to gain exposure from the rest of the community. I would really appreciate any help on this matter.