I'm using an msgeq7 with the reference design applied in an automotive environment. I pass the audio through, but get alternator whine feedback on the audio. Do I need to better filter the power to the arduino, or somehow isolate the audio without signal degredation? Using an electret microphone instead of line in is not an option...
Weird... The MSGEQ7 is running off a 5V regulator, right? The regulator should keep power-line noise out of the circuit.
I wonder if it's a ground loop... If everything is hooked-up and running, and you break the signal connection to the MSGEQ7 (without changing disconnecting the grounds), does the noise go away?
The MSGEQ7 is indeed after a 7805 and a few caps, but does this filter out ground noise? Not only is there alternator whine in the audio, but also if I set a Flashing pattern, which does not use the MSGEQ7 input, there are clicks/pops in the audio in time with the flashing. Disconnecting the board and connecting the phone directly to the stereo does away with both of these.