Arduino and Multiplexer: 16 I/O from 5 pins

Demonstrating using a CD4051 multiplexer chip to get 16 input/output (digital or analog) from 5 pins on the Arduino. I'm reading doing analog reads on 8 CdS cells and using those values to output to 8 LEDs.

Gorey details at http://dawson-station.blogspot.com/2010/01/mux-demux-cd4051-parlor-tricks.html

Category:

Science & Technology

Tags:

• Arduino
• multiplex
• mux
• demux
• microcontroller

[McGuywer]

What's the 5th pin for? 3 pin for A, B, C on the chip and the 4th pin as LEDs sink / photodiode common input.

But I believe with charlieplexing you can light up 20 LEDs from 20 photodiodes from 5 pins, without the CD4051.

[aspro648]

Three pins are addressing (A, B, C), and two are common input outputs, one set ground and the other to source. The chip handles 8 IO, but by switching the common IO pins you double that.

I've not done much more than look at charlieplexing. It looks like a programming headache to me. Hardware and software design have to meet somewhere reasonable.

[aspro648]

@McGuywer

Three pins are addressing (A, B, C), and two are common input outputs, one set ground and the other to source. The chip handles 8 IO, but by switching the common IO pins you double that.

I've not done much more than look at charlieplexing. It looks like a programming headache to me. Hardware and software design have to meet somewhere reasonable

[maubarr]

great program it would be excelent if i can see the code please

i need to know how that multiplexer works