Yes. But this is what your 8-bit FA will do, assuming you have strung them together correctly. How did you connect the eight separate 1-bit FAs to make the 8-bit FA?I would look at each bit position and add them up and carry over if it is necessary. If I did this right the answer should be: 8.
For the remainder of the "Sign Changer" symbol I am creating I am not limited to any specific gates or logic. I was only limited on what I could use to create the Full Adder - I am also limited on what I can use for a segment display but that is in the next step of the assignment.First, draw a schematic in which you have the following signals: A (the 8-bit input), N (the signal that is HI if you want to negate the input, so it comes from your pushbutton) and Y (the 8-bit output). You have available an 8-bit adder and other 2-input logic gates (what are your constraints at this level?). Hint, you can do it with your FA and eight XOR gates.
Note that, because your top level circuit has no B input, you can actually implement the whole thing with just a slightly modified FA circuit (of course, it would no longer be an FA circuit, but that's fine). I wonder if that would be worth some extra credit for you.
Yes. But this is what your 8-bit FA will do, assuming you have strung them together correctly. How did you connect the eight separate 1-bit FAs to make the 8-bit FA?
That's the easiest way to do it and if you are confident that you've done it correctly, then that is great. Just be aware that we haven't had the opportunity to verify your implementation and so if you DIDN'T do it right, things could get confusing down the road. But an RCA is simple enough that you almost certainly did do it correctly.I would under the impression that I would assemble the Full Adders into a RCA and that is how I would be taking in the input.
Here is how I am planning on setting it up - again my amazing MS Paint skills there.That's the easiest way to do it and if you are confident that you've done it correctly, then that is great. Just be aware that we haven't had the opportunity to verify your implementation and so if you DIDN'T do it right, things could get confusing down the road. But an RCA is simple enough that you almost certainly did do it correctly.
Your diagram only shows a 4-bit adder, not an 8-bit adder.Here is how I am planning on setting it up - again my amazing MS Paint skills there.
http://i.imgur.com/JUothd0.png
I took a look at what you said earlier with using 8 XOR gates, but am confused on how that will be a solution to my problem. If I tie in Switch0 to both A[0] and B[0] that will not give me the output I desire.
Yep.I figured out the answer to my question. I was trying to think of a way that I would have to connect up 8 unique switches to 16 different inputs, but I was thinking about it incorrectly.
When you say "this will only be needed...", what is "this" referring to? Connecting 8 unique switches to 16 different inputs? I don't see what else the pronoun "this" can be referring to.Since I will be using this to change the sign of my number this will only be needed in the case that my number needs to be changed to a 2's complement.
But you don't want B[0] = 1 when you aren't pushing the button. How will you accomplish that (it's easy)?. Also, what do you mean by "negated values froming from A[0-7]." The A[0-7] are INPUTS to your FA, where are these negated values coming from.So I will take inputs A[0-7] and connect them up as those will be my switches, but then B[0] = 1 since that will be 0000 0001 which will be needed to be added to my negated values coming from A[0-7].
I don't see why. It is a purely combinatorial circuit. So what if it glitches? It is going to be glitchy anyway.Also, you are, probably, going to need to debounce your button inputs...
I should have added a caveat that I only drew 4 out of the 8 on there out of time constraints. I have figured out what I need to do with my inputs and how to handle that. Now my next obstacle is telling it which path to take when I press the button that will change the sign and initiate the 2's complement conversion.Your diagram only shows a 4-bit adder, not an 8-bit adder.
Your 8 switches only control the A inputs (or the B, but not both).
My B[0] would be hard-coded to be 1. Then B[1-7] would be all connected to GND. Then, for all of my inputs, B[0-7] would be = 0000 0001. Now if I add that to inverted inputs from A[0-7] (1's complement of my input) it would give me the 2's complement. For example:Yep.
But you don't want B[0] = 1 when you aren't pushing the button. How will you accomplish that (it's easy)?. Also, what do you mean by "negated values froming from A[0-7]." The A[0-7] are INPUTS to your FA, where are these negated values coming from.
I am using Xilinx to construct the circuits themselves and then they will be uploaded to the Digilent Basys2 boards for actual physical testing. I believe I have finished the first portion of the assignment, but now I am having to work on the part where I do a 4-bit to 7-bit conversation. I have the truth table set up, but now my restrictions for setting up this circuit is that I may only use SEVEN 8x1 muxes, and 1 inverter to accomplish this. I have another thread going on this topic if maybe you care to take a peek and give some suggestions of advice.Are you writing this in Verilog, VHDL, Schematic Capture, or <other>?
What are the restrictions for the output to 7 segment?
I'll let WBahn finish his lesson.
So I have a data input, D, and a control input, C. I want the output, Y, to be equal to D if C=0 and D' if C=1. Capture that in a truth table.XOR? I am guessing. Not too sure if I am able to visualize what you are asking.