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Visitor f.vermersch
Registered: ‎03-13-2019

Force the use of the SLICE / CLB in spartan-3E FPGA


I need to use a CLB in a particular way on my project.

I have 8 inputs. My function is the following one :

out_Y(i) <= in_F(0) or in_F(1) or in_F(2) or in_F(3);
out_X(i) <= in_G(0) or in_G(1) or in_G(2) or in_G(3);


I need to use the same SLICE for both operation. All the F inputs need to be mapped on the CLB inputs F, idem for G, and my output X and Y are completely independant. 

When I use the tools in an automatic way, two different SLICEs are used. How can I force the tools to use only one ? Attribute, constraint, manual placement ...?

Thank you

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