I was using a FFT Megafunction v12.0 to calculate 512-point FFT, and evaluating it on a DE2-115 board, which has a Cyclone IV E FPGA. The issue I have with this Megafunction is that it always gives incorrect results in the first two run, and gives the correct results in the third run and after, given that I feed the same data into the FFT core. Have any of you met the same problem? I don't understand why this is the case? Is it something to do with the Megafunction itself or it is related to my FFT controller design. Any input is welcome.