Hello, I have a further question now:
Beside the filter I want also generate sine-waves (0Hz-500Hz) with the Arduino.
I thought I could use one of these methods:
DDS
http://interface.khm.de/index.php/lab/experiments/arduino-dds-sinewave-generator/
DAC (Digital Analog Converter)
but they are maybe to heavy for the microcontroller (slow sample rate). I did some tests and the filter didn’t work anymore.
What do you think, it’s principally possible to use a filter and generate sine-waves simultaneously?
I found also this Audio Shield:
Maybe that’s a good solution because it works “asynchronously as an interrupt, so the Arduino can perform tasks while the audio is playing.”
What do you think about? Do you know maybe other methods to generate sine-waves which don’t overload the microcontroller?