I'm a bit new to ZYNQ devices, and embedded systems in general.
I'm trying to get a 20 MHz SPI to come out of PMOD JA, and it is indeed coming out. The problem is at the frequency I have it set to (20MHz), the square wave seems to be slewed out ( All triangles, no squares). I increased the Slewrate in the .xdc file, and the drive current, but I still have the same problem. When I lower the frequency it tends to be more square (as you'd expect), but at 20 MHz, it is just not happy, as can be seen in the picture below. The Clock is in Red and the MOSI data in Blue.
I assumed that the PMOD ports could handle this frequency, was i just wrong?