Program not working as expected

You're doing a check for rising_edge(clk_out) inside a process that is only sensitive to clk16. Your next state logic should be in a separate process, sensitive to clk_out.

Also, you need to code your bidirectional (or is it supposed to be a tri-state?) correctly. It should look something like this (replace from_core and to_core with what the pin should be when it's an output and when it's an input:

	start <= from_core WHEN oe='1' 
		ELSE 'Z'; 
	to_core <= start;

There should be some type of output enable control signal for an inout.

Finally, you're doing an if check on start being 0, but then setting start to 0 as an action in that same if check. I'm not sure what you're trying to do.

#iwork4intel