Arduino Overshoot

[paudav]

My DS1102E arrived today, and I've been playing around with it.  I compensated my probes, and the test signal from the scope looks good.  Nice and square.

So then I hooked up my Arduino, and started flashing an LED, and I noticed that the faster I flashed the LED, the more often I would see some overshoot on the rising edge of logic HIGH.  About 2V worth.  I see a similar (but inverted, obviously) undershoot during the transition to logic LOW, also.

When I slow the LED back down, the overshoot/undershoot disappears.

I realize that my timebase setting here is pretty fast (see the picture), but I was just wondering if anybody happened to know if this is normal behavior with micro controllers (or Arduinos)?  Or is this an erroneous measurement introduced by the scope probes?

Thanks for reading!

-PBD

[Mechatrommer]

if you are using the long gnd clip, its due to the gnd cable loop inductance.