inout line undefined

For a start - this is an Altera forum - for Xilinx specific problems you should really go to the Xilinx forum.

But asside from that - I dont know what things should be? having a quick look over this code, the counter wont start counting until i_en = '1', and you have nothing defined for when count = 0.

And why is io_SD an inout? you never read it, so it should just be an Out.