help: xilinx area constraint warning

[sawaak]

area constraint ratio

Hi,
i got the following warning while synthesizing in xilinx ISE 9.1.03.

WARNING:Xst:2254 - Area constraint could not be met for block <fft_ifft_serial>, final ratio is 298.

before the warning, the following lines appear.
Found area constraint ratio of 100 (+ 5) on block fft_ifft_serial, actual ratio is 303.
Optimizing block <fft_ifft_serial> to meet ratio 100 (+ 5) of 4656 slices :

what does that mean????

thanks
sawaak

 

[ehsanelahimirza]

found area constraint ratio of 100

if it is the area constraint then the FPGA u have selected is not having that much gates............try by changing ur selection of hardware

 

[salma ali bakr]

area constraint could not be met for block

it means that your design is taking 303 but it should take 105
so it's short by 298
so you have to change your code to fit your design on the hardware

 

[echo47]

xilinx xst:2254

The XST User Guide (I have 9.2i) has some words describing the area constraint ratio message in chapter "FPGA Optimization", section "Speed Optimization Under Area Constraint".