Now and again there’s a need to expand the I/O capabilities of your chosen micorocontroller, and instead of upgrading you can often use external parts to help solve the problem. One example of this is the 74HC4067 16-channel analog multiplexer demultiplexer. That’s a mouthful – however in simple form it’s an IC that can direct a flow of current in either direction from one pin to any one of sixteen pins. Another way to think abou it is that you can consider the 74HC4067 to be a digital replacement to those rotary switches that allow you to select one of sixteen positions.
74HC4067 16-Channel Analog Multiplexer Demultiplexer – [Link]