I would like to perform my own memory using LUTs with one input in ise in schematic.When I make test for one LUT in modelsim I always have 0 at the output whatever the bit at the input.What should I do to get the same bit in the input and output of LUT? How do I connect LUTs to obtain a memory?
In the HDL world, you typically instantiate a different entity which is a memory entity, NOT a LUT.
Your schematic library most likely has a different symbol to use. According to the Xilinx Libraries Guide, Spartan-3 has a number of primitives called things like “RAM16X1S” and “RAM16X1D” and so on. Try looking for these.