Using DSP48s with for addition with a latency of 2 yields the best timing performance, from experience and Xilinx's recommendations, which is why it's hard-coded. -Suraj
On Thu, Jul 28, 2011 at 11:53 AM, Samuel Tun <[email protected]> wrote: > Yes, unchecking the DSP48 adders allows me to change the add latency. > I had that option selected because it was one of the recommendations > towards meeting time constraints. I will test this out now and see. > Thanks for your help. > > -Sam > > > On Thu, Jul 28, 2011 at 12:32 PM, Hong Chen <[email protected]> > wrote: > > Hi Sam, > > Did you activate the 'DSP48 adders in butterfly' option in the > > Implementation section? The add delay value will be fixed to 2 when that > > option is on. Would you mind try turn off that and see if it works? > > Thanks, > > -Hong > > > > On Thu, Jul 28, 2011 at 9:24 AM, Samuel Tun <[email protected]> > wrote: > >> > >> Hi, > >> > >> I am using the latest BWRC libraries in Linux, and I found that I > >> cannot change the add delay values in the FFT block mask. Back when I > >> was using the 10.1 libraries, changing this delay value along with > >> other parameters along the PFB chain allowed me to meet timing > >> constraints for a 1 GHz clock without having to break masks and > >> putting multiple fixes all over the place. Does anyone know if this is > >> just happening to me, or if it was hardcoded, and most importantly, > >> how can I change this value? > >> > >> thanks ya'll, > >> Sam Tun > >> > > > > > >
