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Altera_Forum's avatar
Altera_Forum
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15 years ago

Missing Source Error - Buses & Nodes = Help!

Hi there, I'm currently doing a project for my Digital Systems course. I'm fairly new to Quartus and am attempting to compile a simple 4 Bit BCD Adder using block diagrams.

I was hoping that someone could describe to me why I cannot do this (I believe the problem area is highlighted):

http://img.photobucket.com/albums/v232/MasterChief117/problem.png

When I try and compile, it gives me:

error: node "i[1]" is missing source

error: node "i[2]" is missing source

error: node "i[0]" is missing source

error: node "i[3]" is missing source

All I want is to have I[3],I[0] at 0 permanently, and I[1],I[2] read the value the output of the OR gate. Any pointers?

Thanks in advance,

Andrew

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    You can do this way, for example:

    Name the wire connected to the ZERO input pad as "zero"

    Name the OR gate output as "out_or"

    Draw a piece of conduit from the A[3:0] input port of adder but DON'T connect it to anything else; rename it as "zero,out_or,out_or,zero"
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    In schematic design, you can use the wire and constant symbols to connect the inputs as required.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    In schematic design, you can use the wire and constant symbols to connect the inputs as required.

    --- Quote End ---

    Thank you very much both of you. I'm just tried the method with constant and wire. I feel like a bit of a fool asking, but I'm having trouble figuring out how to use the constant symbol. It doesn't appear to take to wires. I tried assigning it to some named wires but got compilation errors saying some of my wires didn't have inputs. Would you be able to offer a brief explanation on how to use it? Google and forum searches are coming up empty.

    Thanks!!
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    My suggestion was to use constant to supply constant values and wirre to connect different nets. But instead of constant, you also have GND and VCC for 0 and 1 binary values.

    Schematic entry is perfect WYSIWYG, just play around and figure it out.