4-way 16-bit mux

[BrandonK]

BrandonK again, I am having another problem. I am trying to build the 4-way 16-bit mux but the hdl implementation seems to be having problems, the test script is giving me errors. I have looked at the hdl file an have found nothing wrong with it. Could someone please take a look at it and see if you can find any errors. I have also included a picture of my diagram of the implementation on paper. I am really tired, I might need some sleep.

Here's the link for the files: http://www.filedropper.com/4waymux
                                     (mirror) http://www.mediafire.com/?9a16a52z0iyp433

Thanks, again. :)

[BrandonK]

Ok I have got it working by switching the two selectors, sel[0] is now sel[1], and sel[1] is now sel[0]...Could someone take a look at my diagram and tell me why I need to switch them?

It just doesn't make any sense, before I switched them I went through every 1-bit possibility and it worked perfectly, now after switching them I went through all the possibilities and it no longer works, but the hardware simulator says it works, soo... Any ideas?

[culchie]

Hi Brandon
    I just had a look and I haven't given it the time to understand it, as it is quite long.
    What jumps out though is that you are doing it the really hard way.
    How long will your Mux8Way16 be if you try and do it this way?
    Think about it. Why are you using 1 bit Muxs inside this chip which has 16 bit inputs?
    Also can I suggest that you have a look at this thread

[cadet1620]

Hi BrandonK,

In the truth table on your schematic, label the select bits as per fig 1.10 in the book.  You should see the problem.

I strongly recommend implementing the chips in the order they occur in the book.  Once you have Mux16 you can use it instead of 16 repeated groups of commands and save a lot of typing.

culchie's post came up as I was looking at this;  so I don't have to say that...


[You might want to become a registered member, then people can send you private messages with stronger clues that they may be reluctant to post on the forum.]

--Mark

[BrandonK]

Thanks culchie, I've switch to the 16 bit Mux and it is alot smaller, but I still don't understand why I need to switch sel[0] and sel[1]. Could you take a look at the diagram and see if you can figure out why I need to switch them. Thanks.

[BrandonK]

Ohhh, I can't believe I missed that. Thanks so much you guys, I appreciate it very much.