Hi. I'm trying to use the Xilinx FFT generator 9.0 (for a project that's trapped in the sticky goo of Vivado 2015.4 due to third-party IP).
The manual's description of the startup sequence for the realtime FFT mode is a bit confusing. I see that tvalid is used to signal the start of the first data frame and then ignored for the rest of the frame. But then the manual says that tready will be deasserted by the core for one or more cycles as the FFT engine starts working.
This seems wrong to me, since it's a realtime FFT that should be able to accept realtime data in real time. I can't stop the clock on the analog signal coming in from the telescope. Is the first frame just assumed to be garbage? (That would be okay.)
What is the startup sequence, really, for realtime mode?