My clock is a clock though PLL. This waveform is messy
Messy? What do you mean?
the project is UART，they logic is very simple。The frequency of clock is 50Mhz. however, they waveform is so mess. I don't know why the waveform like this.
Without an explanation as to why this is "messy" or showing the design, there's no way we can help.
Have you zoomed into the waveforms (left click)? Do they look correct when you do?
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