FPGA Graphing Calculator
December 2021 - January 2022
Status: Completed
Embedded Files
This project is based on the DE10-Nano System-on-Chip (SoC) in order to design a fast, customizable, and HDMI driven graph. The FPGA portion of the chip was used for driving the HDMI output (written in Verilog), and the HPS side was used for the graphing functionality (written in C++). It can graph any amount of curves and has options for animated drawing due to the versatile C++ library.
Purpose of the project
After learning the basics of FPGAs in Embedded Design during the fall semester of 2021, I challenged myself to learn more in depth about FPGAs than what was taught. Although I will formally learn Verilog in more detail during spring 2022 classes, I wanted to challenge myself to make a graphing application using an FPGA. In doing so, my goals were learn more about Verilog, HDMI, and the basics of creating a project using FGPAs and System On Chips.
Early prototype of the graph with the pixels hard-coded in order to test the HDMI display
Outcome
After completion of this project, I have now proficiency in:
Verilog
Basic HDMI interfacing
Timing analysis
Creation and optimization of RAM for a larger system
General FPGA development workflow
The project exceeded my expectations with the final implementation being fast and easy to use. In the future, I may come back to this project to add more features such as a user interface with a keyboard or other interfacing options.
Steps
Set up HDMI interface
The first step of the project was to learn how to output through HDMI on the DE10-Nano. After following documentation and learning through examples, I was able to code an interface. Although the goal of the project was to simply make graphs, I wanted to make a system that was reusable for any application. At this point in the project, the pixels were hard coded in to achieve the three lines shown in the photo above.
Set up HPS-FPGA Interface
In order to connect the Linux system to the FPGA, the HPS-FPGA bridge was used. By setting up a 25-bit bridge, the position and color information can be sent over to the FPGA (20 bits for which pixel, 4 bits for color, and 1 enable bit). Next, RAM was created in order to store the pictures so they can be accessed asynchronously to set and read. At this point, all that was needed to complete the project was an easy way to code any graph.
Create C++ Graphing Library
Lastly, a library was made in order to graph any function. It works by accessing the memory addresses of the HPS which the FPGA reads from. At the end of the project, what is left is an extremely easy to use coding interface in which any 2D graph can be made at any color. In addition, I added animations, gridlines, and a movable origin, so that the user can view an easy-to-read graph at any x-y range. With this addition, the project was complete.
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