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font-size: 12px;" lang="x-western">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
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.