Hello!
I was playing around with the example code that has a High Pass and Low Pass Filter cycled through for the EVAL-BF706M-EZLITE Evaluation Board. I wanted to try creating my own effects and basing the backbone off the example code. The function AudioFilter(const fract32 dataIn[], fract32 dataOut[]) is called and the input is the audio samples that are being communicated to the DSP and the output is being directly copied to the Tx Buffer. So I figured that if I made a function in place of the iirdf1_fr32 function found in AudioFilter.c, I would be able to manipulate the dataIn and write the manipulated data to the Tx Buffer. However when I attempted this I heard a High pitch noise when I press the button that calls the filter function. After I noticed this I tried just directly writing the dataIn[] structure to the dataOut[] without calling the iirdf1_fr32 function and the noise appears again when the filter is enabled. However when I write the input data directly to the output when the iirdf1_fr32 function is called the noise is not present. The noise reappears again if the filter initialization is not called. Is the iirdf1_fr32 function altering the data in in some way that I'm missing? Or is it possible there is something that is happening with the delay lines during the filter initialization that prevents the high pitch noise that I am hearing?
Sorry if the description of the problem is kind of vague, I can provide any information that is necessary!
Thank you,
Ethan
