[Noisebridge-discuss] Sanity check on LED matrix design.

Daniel Pitts Daniel at coloraura.com
Sun May 20 09:18:14 PDT 2012


Hello,

I'm going to try to make a simple LED matrix display powered by an 
Arduino, and wanted to validate my approach with the more experienced 
people here.

My goal is to have something that will allow several "brightness" values 
for each LED. In other words, I'd like each LED to be able to be 
independently one of:  full bright, 3/4 bright, 1/2 bright, 1/4 bright, 
full dark.

The design has 3 of the Arduino outputs connected to a 74HCT138, to 
decode the "column", and then 8 other pins connected to each of the 
"row" (with appropriate resisters).

The software part of this would run through each column, and enable the 
appropriate rows.  I'm hoping to put this process on a 4ms timer, so 
that I can interleave on/off states depending on the desired brightness, 
and still have the entire matrix update at around 50hz

Does this seem like a reasonable approach, or is it likely to cause too 
much flicker?  Does anyone know if the 74HCT138 can keep up with this 
pace? How about the Arduino? The Arduino will be doing more than just 
the display part of course, since I'll have to actually create something 
worth displaying.

Thanks,
Daniel.
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