how to make an 8-3 encoder using 4-2 encoders

[lamiajoyee]

encoders

hello there! can anybody please tell me how to make an 8-3 encoder using 4-2 encoders or using logic gates. please help me. i will be grateful to you

 

[keith1200rs]

Are you talking about digital or analogue multiplexers? Do they have a disable? For two 4-2 analogue multiplexers, if they have a disable you would connect the outputs together, use the same two control lines connected to D0 & D1 of each, then use the D2 for one chip enable and NOT D2 for the other.

Keith.

 

[AdvaRes]

Fill Karnaug map for both the 8-3 and 4-2 Encoder and then extract the output equations relating 8-3 outputs to the 4-2 output. Then implement this fuction using simple logic gates to transform the 4 outputs of the 4-2 encoders into only 3 output.

Advares.

 

[keith1200rs]

If it's digital the same sort of solution will apply, just add an inverter, assuming it has an enable:

Keith.

 

[lamiajoyee]

im talking about 8-3 encoders. the figure you gave me is of a decoder

 

[keith1200rs]

Oops, sorry. I must read more carefully

In my defence, I was just working on some 8 way analogue multiplexers :|

In which case it's a bunch of logic gates:

http://tams-www.informatik.uni-hamburg.de/applets/hades/webdemos/10-gates/45-priority/priority83.gif

Keith.

Added after 58 minutes:

Actually, you probably can combine a couple of 8:3 encoders. This may be helpful:
**broken link removed**

Keith

(I'll get this link to work if it kills me!)