Building an LED matrix is a fun project, but it can be a bit of a pain. Usually it starts with hand-soldering individual LEDs and resistors together, then hooking them up to rows and columns so they can be driven by a microcontroller of some sort. That’s a lot of tedious work, but you can order an LED matrix pre-built to save some time and headache. You’ll still need a driver though, and while building one yourself can be rewarding there are many pitfalls and trade-offs to consider when undertaking that project as well. Or, you can consider one of a number of drivers that [deshipu] has outlined in detail.
The hangups surrounding the driver board generally revolve around the issue of getting constant brightness from LEDs regardless of how many in the row or column are illuminated at one time. Since they are typically driven one row or column at a time, the more that are on the lower the brightness each LED will have. Driver boards take different approaches to solving this problem, which usually involve a combination of high-speed scanning of the matrix or using a constant-current source in order to eliminate the need for resistors. [deshipu] outlines four popular chips that achieve these purposes, and he highlights their pros and cons to help anyone looking to build something like this.
Most of these boards will get you to an 8×8 LED matrix with no problem, with a few going a few pixels higher in either direction. That might be enough for most of our needs, but for something larger you’ll need other solutions like the one found in this 64×32 LED matrix clock. There are also even more complicated drivers if you go into extra dimensions.
Photo credit: Komatta [Public domain], from Wikimedia Commons
8 thoughts on “A Guide For Driving LED Matrices”
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Staring at the LED picture and scrolling up and down makes for a cool optical illusion.
yep, I only came to see if others spoted this
A while back someone posted a link to a nice table that listed the most efficient way to control a given # of LEDs vs number of available pins, comparing a lot of methods like shift registers, charlieplexing, and even “use a bigger microcontroller”. Haven’t been able to find it, anyone got a link?
Did you mean this one?
Ooo, that’s a neat breakdown.
The only recent spreadsheet that I could think of which compared the various methods was about input matrix scanning rather than LED driving…
That’s the one! Thanks
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