What is a Testbench and How to Write it in VHDL? Once you 32 bit ripple carry adder verilog code writing code for your design, the next step would be to test it.
One method of testing your design is by writing a testbench code. A testbench is used for testing the design and making sure it works as per your specified functionalities. Using a testbench, we can pass inputs of our choice to the design to be tested. The outputs coming out of our design can be viewed on a simulation waveform or text file or even on console screen. Lets see how this works with an example. The design above is a 4 bit UP counter with active high asynchronous reset.
The design has 2 inputs – a clock and reset and one output which is the count value. In order to write a good testbench we need to first understand the design. The design we have here is a very simple one, to it shouldn’t be too complicated. Let me show you a sample testbench for this design. Notice that the entity port list is empty here. It’s recommended to use CAPITAL letters to define constants.