Multiplexed LED Driver for RGB LED Bar Graph

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Multiplexed LED Driver for RGB LED Bar Graph

Post by ktmglen » Mon Jul 24, 2017 1:52 pm

I’m just sharing this project of mine in case any body else is still trying to figure out how to drive the Sparkfun RGB LED bar graph.

A few months ago, I purchased one of the common-anode 48-segment RGB LED bar graphs from Sparkfun. It has 144 LEDs arranged into a 16 x 9 matrix. Unfortunately, 16 x 9 is one LED too big to be driven by most (all?) of the multiplexed LED driver ICs so I had to build my own multiplexed driver.

I built the driver to be electrically-compatible with the 32x32 RGB LED matrices that Sparkfun also sells. I used an FPGA and some existing RTL and software to drive a pseudorandom noise pattern to the bar graph. It worked well and I wrote a blog post about it here: ... bar-graph/

Last week, I decided that for a potential project I may build soon that the Digilent Arty FPGA board was too big to stuff into the project’s small enclosure so I needed something that could drive the bar graph equally as well but physically much smaller—enter the Teensy 3.2 microcontroller board.

On Sunday, I hooked up the Teensy 3.2 board to my driver board and the RGB bar graph. I then wrote a small sketch using the Pixelmatix SmartMatrix 3 library to drive the RGB bar graph. It worked just as well as with the FPGA. Blog post about moving from the FPGA to the microcontroller here: ... eensy-3-2/


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