I don’t think that it’s a 10X problem. When I bit-bang the output with the same setting on the nano, everything looks fine (in 1V/div, 2V/div and 10V/div).
I verified that the issue exists on both the Seeeduino as well as the Arduino MEGA.
When I look at it on a different scope, I get the attached waveform (1V/div, 200us/div, same as DSO nano)
