AN-203 - I/O Expansion
suggests why devices are often labeled decoder/demultiplexer * depending on how you connect it, it can be used to perform either operation.
The 74HC138 and 74HC139 are two examples of a decoder/demultiplexer.
The former is a single 1 of 8 device while the latter is a dual 1 of 4 device.
The
ZBasic AN-203 I/O Expansion Techniques Introduction Application Note On more complex projects it is often the case that more I/O lines are needed than the number that are available on the chosen processor.
In this situation, you might first try to redesign the application to require fewer I/O lines.
For example, you may be able to use a given output for multiple purposes.
If you still need additional I/O lines, there are several techniques that you might employ, separately or in combination, t
