Try adder latency 1, multiplier latency 2, bram latency 3. Be sure to optimise to use DSP48 multipliers and tick any boxes asking to "pull adders into DSP48s".
This should allow adders following multipliers to use a single DSP48 slice, with registered input and output (making for a shorter signal path and higher speeds). You might want to check the physical layout of a completed design (using floorplanner) to see what it's actually done. This should help you to figure out why things aren't optimal. If it comes down to it, you might have to resort to manual placement of some bits (something I've never attempted). Jason On 03 Sep 2010, at 3:58 PM, Danny Price wrote: > Hi all, I'm trying to get the tute 3 spectrometer design running at 250MHz, > and am running into timing issues. The timing report suggests problems in the > PFB and FFT -- does anyone have some recommended settings for the PFB and FFT > (i.e. latencies etc), before I start adding delays haphazardly under the mask? > > Also, any suggestions on a methodical strategy to meet timing? > > Thanks > Danny >
