Pages created and updated by Terry Sturtevant Date Posted: October 31, 2019

PC/CP220 Digital Electronics Lab

Multiplexer Lab



For this lab consider a MUX with one output and four inputs, where one of the four inputs must be selected for output through 2 selection lines.


Suppose these are the signals going in on each of the inputs, from I3 to I0:
multiplexer timing

If the select inputs are set to 0, the output will be:
multiplexer timing bit 0

If the select inputs are set to 1, the output will be:
multiplexer timing bit 1

If the select inputs are set to 2, the output will be:
multiplexer timing bit 2

If the select inputs are set to 3, the output will be:
multiplexer timing bit 3

So if the select inputs cycle through all four possibilities, the output will be:
multiplexer timing all

Background: Strobe, Gate, and Enable pins

Certain chips, like the multiplexer here, have "extra" inputs which allow more control over the outputs. With this multiplexer, there is a pin called strobe. This pin has to be connected correctly for the device to work as expected. Look at the device truth table to figure out whether this pin needs to be tied high or low.


Always start by creating a new folder. Do not put new files in the same folder as your previous projects!
Then create a new project.
Then create a BDF file. Do not start by creating a BDF file. Make sure all of your files are in the project folder.

You will use Altera Quartus II to draw your circuit diagram, and use the 74153M multiplexer from the others | maxplus2 library.
choosing a library

Quartus II may use different pin names than the datasheet (from ON Semiconductor) or the lab writeup. You should be able to figure out which pin maps to which based on the number and function of the various pins.
Simulate your circuit to confirm that the multiplexer works as expected.

Hint: Look at the inputs to the multiplexer and see if there are logical ways to group the inputs. You can make more than one input group in Quartus, and not all of the inputs need to be in a group.

Note that you can change how fast a group counts with the value in the "Count every" field.
changing count value

Demonstrate the circuit to the lab demonstrator.

After Quartus II is closed, if you worked on the C: drive copy your directory to the E: (flash) drive or to the I: drive, since C: drive files will be erased when the computer is shut down.


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