Monday, March 17, 2014

16 RGB blinkie take two

The previous multiplex circuit wasn't working out. I was doing a modified CharliePlex but with the different colors (with different forward voltages) involved and the common anode configuration, I couldn't avoid ghosting while driving 16 RGB LEDs from 8 I/O pins.

This one uses a 74HC595 chip, I'll be using a 74HC164 in the final design to save another 20 or 30 cents. The code to drive this is far simpler, the board layout should be almost trivial to do in comparison to the other one, and the performance is better.  The extra chip only adds about 30 cents to the whole board.

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