For the first lab and first project of ELEC 220 we will be focusing on the creation of circuit diagrams using Altera’s Quartus II Web Edition. In addition to simulating these circuits on a computer, we will also be configuring Field-Programmable Gate Arrays (FPGAs) from these diagrams. Our target platform will be Terasic’s DE0 Development and Education Board which uses Altera’s Cyclone III FPGA chip.
FPGAs
An FPGA is an integrated circuit, composed of many logic elements, which can be reconfigured by the user to reproduce a variety of circuits. Each logic element contains several different logic gates and memory elements which can be used to recreate a wide variety of circuit components. The DE0 board we will be using has over 15,000 logic elements although we will only be using less than 1% of these, even for the calculator project. Hopefully, after completing this project you will have a better understanding of the power and versatility of FPGAs.
FPGA Configuration
In order for an FPGA to emulate a desired circuit, it must first be set to the proper configuration specified in a data file uploaded to the board. This data file is created, and often uploaded to the board, using FPGA design software such as Altera’s Quartus II. By providing Quartus with information regarding the specific FPGA to be configured, a Quartus project can be easily replicated on an FPGA, shortening delays between concept and protype stages in designing circuits.
HDL vs. Schematic Diagrams
There are two ways to specify the intended function of a Quartus project. The more straightforward method is to simply create a schematic diagram of the desired circuit as though you were drawing it out on paper or building it on a breadboard. This has the advantage of being very easy to grasp, however, it requires you to work out the logic for the entire circuit and lay out all the components. The other more abstracted method is to use a Hardware Description Language (HDL) such as Verilog. Writing using this specification language allows you to specifiy the intended function of the circuit from which Quartus creates an optimized circuit layout. Although this method does not give you as much individual control over the design, it allows you to more easily go from concept to end product by tasking your computer with the bulk of the design work. However, for simplicities sake, we will be using schematic diagrams for the majority of this course, with HDL files provided to you for use in later designs.
