Electronic – 8:1 multiplexer to 6:1 multiplexer

multiplexer

I have 6 inputs that I want to insert in a 8-1 multiplexer. I just want to know how to modify the 8-1 mux to support only 6 inputs. I mean the last two rows on the truth table of the 8-1 won't be available.

This is the 8-1 mux I am using:

and its logic table:

I only want to use the D0 to D5 inputs.

Best Answer

Assume that D6 and D7 are always low. Trace those signals through the gates in your design. If you find gates whose output values must always be the same, those gates can be removed and their output signals changed to a direct connection to logic '1' or '0'. Repeat until no gates are removed. Then remove unnecessary direct connections to logic '1' or '0'.

Related Solutions

Electronic – How a 2-1 multiplexer (MUX) work

The best way to get a proper understanding is to write down the truth table completely. You have 3 inputs (A, B, S), so this will give you 2\$^3\$ = 8 combinations:

S  A  B | S' C  D | Z
--------+---------+--
0  0  0 | 1  0  0 | 0
0  0  1 | 1  0  0 | 0
0  1  0 | 1  1  0 | 1
0  1  1 | 1  1  0 | 1
1  0  0 | 0  0  0 | 0
1  0  1 | 0  0  1 | 1
1  1  0 | 0  0  0 | 0
1  1  1 | 0  0  1 | 1

It's often useful to add intermediate results to make things more clear. I added a term \$C = (A \land S')\$ and \$D = (B \land S)\$. Now it should be clear that \$Z = (C \lor D)\$.

Building an 8 to 4 Encoder from a 8 to 4 Multiplexer

First of all, the 74HC4052 is not an 8-to-4 multiplexer, it is a dual 4-to-1 multiplexer with common select inputs.

If I understand correctly, you want to connect a total of 8 switches, four at a time, to your microcontroller. You would need two of these chips in order to do that.

However, you could connect them two at a time to your microcontroller with just one of these chips.

Best Answer

Related Solutions

Electronic – How a 2-1 multiplexer (MUX) work

Building an 8 to 4 Encoder from a 8 to 4 Multiplexer

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