Board signals

[Altera_Forum]

Hi, 

 I'm working with a Cyclone II board from Knjn and suspect something isn't right with some signals coming from the board.   All I'm trying to do is to use the LPM_COUNTER as a frequency divider. Depending on the frequency, the amplitude isn't the same and most importantly the signals do not look square at all.   Could you please have a look at the pic attached and let me know if it seems alright ? It should be a 1.5 MHz square signal. The frequency part looks alright to me however the square part isn't neat.   I've tried it on two different boards, on several pins, with different probes.  I would be very grateful for any help.   Best regards,  Jennifer

[Altera_Forum]

Check the ground connection: you get that kind of wave when you have poor ground connection; I mean probe ground not connected or far from measuring point. 

Another guess: are you driving that signal on long lines? If so, that ringing is present on the actual signal and you may need to put some termination to prevent it. I see on the display DC full. If you are using a >100MHz oscilloscope, limit its channel bandwidth to 20MHz. No need to use full, since your probe would catch up a lot of noise, although I think this is not an issue here.

[Altera_Forum]

Thank you for your help, changing and adjusting the probe did the trick.