 <p>What is your desired functionality? I assume: shifting which LED is on every 2 seconds, keeping all the other LEDs off? "Sliding LED"...</p> <p>Also, I am assuming your target is an FPGA-type board.</p> <p>There is no free "wait for X time" in the FPGA world. The key to what you are trying to do it counting clock cycles. You need to know the clock frequency of the clock that you are using for this block. Once you know that, then you can calculate how many clock rising edges you need to count before "an action" needs to be taken.</p> <p>I recommend two processes. In one, you will watch rising edge of clock, and run a counter of sufficient size, such that it will roll over once every two seconds. Every time your counter is 0, then you set a "flag" for one clock cycle.</p> <p>The other process will simply watch for the "flag" to occur. When the flag occurs, you shift which LED is turned on, and turn all other LEDs off.</p>