June 28, 2011 AT 12:50 pm

Drive 16 LEDs with one I/O line

291845-Drive 16 Leds With One I O Line Figure 1

EDN always has fun hacky posts..this one could be handy for a DIY project that wants a bunch of LEDs controlled by a single pin

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  1. joshua johnson

    There great vids on Youtube and primers elsewhere on using these. You can also wire them together or with mux/ demux ic’s for improved results. I’d like to see a learning series devoted to this family of chips

  2. There are a fair number of tutorials around on using shift registers to expand the number of outputs from a microcontroller, but the neat part of the EDN note is that they manage to merge the clock and data onto a single output pin, halving the number of pins normally used (2 to 1.)

  3. My preference is for the PCA9922 from NXP ( http://www.mouser.com/search/refine.aspx?N=4294013638&Keyword=PCA9922 ). It works similar to the shift register except it has constant-current outputs set with a single resistor and can optionally detect open-circuit conditions.

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