read digital information on 4051

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi,
I've read about 4051 on forums, and I've still 2 questions I can't find an answer for:

  1. What if I only need to read digital information on an analogue pin of 4051 from Arduino? To simply use digitalRead()?

  2. As I understand, the change between using the chip as a multiplexer and demultiplexer happens by simply using analogRead() and analogWrite() ?

Thank you,

2

There is neither input nor output with analog multiplexers, it's both at the same time. That will answer both of your questions.

However, this information has been given many times (at least by me) in this forum.

Note that the unswitched connections are high-impedance. This is not like a digital multiplexer. The switched connection has an resitance of about 100 ohms.

3

Thank you for the answer, but how it is not input/output?

for example I found this on the next link:
"4051[ch8242]s in an 8×8 matrix can check the status of 64 digital inputs without using any of your digital I/O;"

http://www.embedds.com/core2duino-dual-core-arduino/

What is a reasonable solution for expanding digital and analogue I/O for Arduino?

What I came to is:
4051 for analogue pins,
74HC595 for digital pins.

Am I right with this please?