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  Working on the matrix in our lab (The Living Room)

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  Each square-segment is 0.2m x 0.2m

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  A close-up of the LED strips we used to illuminate each square-segment

About the Matrix

My brother and I built the 5x5 LED matrix in the summer of 2016. It has 5 common anode columns and 5 common cathode rows with an LED at the intersection of each.

The matrix displays a pattern by applying 12 volts across a cathode-row-anode-column pair, lighting the LED at their intersection. 25 LEDs can be controlled using only 10 IO pins by multiplexing. Each of the 12 volt LED square-segments is lit up by a 5V relay connected to an Arduino through a 2222A MOSFET transistor. To turn on multiple LEDs in a specific pattern, I created an algorithm to switch on one LED at a time and flicker through the required LEDs, one at a time, at a speed too fast for the human eye to perceive.

We designed the LED matrix to help explain how such matrices work and to experiment with code and, for this reason, we scaled it up significantly. The panel is 1m X 1m and each square-segment is 0.2m X 0.2m. I coded it using the Arduino Programming Language to take row and column numbers as input and then display corresponding patterns on the matrix.

Built With

• 2222a-mosfet
• arduino-programming-language
• arduino-uno
• relays
• strip-leds