Here is another video about the project: https://www.youtube.com/watch?v=NjxL4i6Dl8oOverview
This project is one among others built by the Maker Club at my school. Two people worked on this project: me and my friend Anand. We wanted to build a LED board because Anand is about to go to college and wants to have this in his dorm, possibly functioning as a display for music equalizers.
We participated in Bay Area Maker Faire 2017 with this project. I was really delighted to see that there are many people who also are trying to build a LED board, and being able to talk to them and sharing my experiences of building the board with them was for me a pleasure.
How it works/ how to build one
Please visit the How-To section.Workspace
We used the Fab Lab at Santa Clara High School to build the project. Fab Lab is a makerspace available to all students at Santa Clara High School. We were able to discuss the details of the project, solder the LED strips, and test different patterns in Fab Lab.
Image credit: Terrell Lloyd @49ers
Through building the LED board, the most important thing I learned was probably being creative in terms of solving a problem. When the hot glue gun did not stick the LED strips to the board, we tried out epoxy glue. When epoxy glue was too slow for us, we used adhesive squares. When we realized we had enough LEDs, we also improvised to build a 15x15 board instead of a 10x10 board, which was decided after some calculations about the current and our power supply.
Thanks to Matthew Dalton and his team for filming & editing the show & tell video! A more explanatory and more comprehensive video will be uploaded in mid-August.
The 5V and the ground pin is wired in parallel, while the control pin is wired in series. The 5V and the ground pin are connected to another power supply. The control pin is connected to the Arduino, which is then connected to the computer with Glediator running.
Parallel vs. series circuit
We originally wired both the ground pin and the 5V pin in series; however, our advisor suggested that the great amount of current (about 3A) through the 2 pins when wired in series would possibly burn out the wire. Thus, we added bridges between LED strips to wire it in parallel to alleviate the current passed through one LED strips.
Manual Bit-mapping Vs. Glediator
To display a logo, the Glediator software does a poor job in terms of downsizing the image to a lower resolution; thus, we manually bitmapped the image through Photoshop so the logo is recognizable even with only 225 pixels.
How can 1 pin control the colors of 255 LEDs
The LEDs are controlled by hexadecimal RGB values, with 8 bit each to represent the amount of red, green, and blue of a color. The Arduino pin implements the serial protocol, which is basically a shift register. In stead of each LED having a specific address to send the RGB values to, each pin gets enough data before passing the data onto the next pin. The advantage of using the serial protocol is that each pin of each LED does not have to have an address explicitly assigned, making this a scalable system for adding more pixels.