Noisy arduino tone output

Hi all I am trying to build a simple opamp circuit but before I could that I am getting a relatively noisy output. The square wave is fine but visibly there are very sharp over and undershoots not in a pattern rather like static. Any ideas why i connected the UNO to a USB power should not be any noise there ?

Details of the circuit (a schematic) would be nice. Perhaps a scope shot if you can. Was your op-amp unterminated ? Does the ringing go away if you add a 1k resistor to the output ?/