The purpose of these instructions is to create a 4-bit adder in Quartus II. A 4-bit Adder is a simple model of a calculator. It takes in two numbers of 4 bits each, allowing us to take numbers 0-15, but we will be using numbers 0-9. The numbers are then added together. The circuit is made in Quartus II and then is programmed onto a Field Programmable Gate Array (FPGA) which allows the circuit to be used.
This project is intended to be for fun or could be a final project for a class, but is mostly to become more familiar with logic circuits. This project will make more sense if you have already taken or are currently taking a digital logic class and have a basic understanding of logic gates. Some basic commands of Quartus are also covered if you have never used it.
The FPGA has buttons, switches, LEDs, and number displays to accommodate most circuits. Quartus 2 can be purchased for around $3,000-$4,000; although, the web edition of the software is free, but still requires the purchase of an FPGA. I found FPGAs online for around $200. I used the campus software, so I did not have to purchase any equipment. It took me 6 hours to complete the adder from scratch my first time. My hopes with these instructions are for you to be able to complete the 4-bit adder in less than 5 hours. Completion of this circuit will bring you greater understanding and fulfillment with its complexity.
Note: Pictures at the beginning of each page show given steps in the process. They are to prevent confusion
Step 1: Starting Quartus
1) If not already installed, install Quartus onto your computer.
Note: I did not have to install Quartus since I used a campus computer. Follow the installation wizard and everything should work fine.
2) Open Quartus from your main window.
3) The project wizard should appear. Click on create a new project.
4) The first page tells you about the project wizard. Click next to go to the next page.
5) Select a directory to work from.
Note: Any directory is fine. It is simply where you will save your files. It is best to create a folder specifically for any project you do.
6) Name the project 4BitAdder. This will also appear as the top level design entity.
7) Click to the next page.
8) We will be starting from scratch, other than the basics that are included in the program, so click next again.
9) Choose the family name of the FPGA you have. (Cyclone, stratix, etc.)
10) Your device will have a specific name given in the scroll bar. Select it and hit finish. The last two pages will not be changed.
a) To figure out the family name and specific name of your device, find the processor on the FPGA. It is a larger chip with ALTERA written on it.
b) The family name will be on the second line in slightly smaller print than ALTERA.
c) Below the family name is the device’s specific name, containing letters and numbers.
11) The project will load with a blank screen saying Altera Quartus II. In the upper left corner, click on file, and then click on new from the drop down menu that appears.
12) Select Block Diagram/Schematic File (BDF) from the window that appears. The screen will be white with small dots.
13) Save the file right away under the name 4BitAdder. The file should default to this name when the save screen appears.
Note: To save, click file, then save as. You can also click on the floppy disk in the tool bar to save after parts are added.
Caution: Save often. Computers and software are known to crash. To keep from losing information and redoing steps, save your files whenever you think of it.
This file will be where the main project comes together. Smaller components will be created in other files and made into a block, where only the inputs and outputs are seen without all of the gates and mess. These blocks are smaller and create less clutter for the project.