Troubleshooting VHDL Circuit: Undefined Symbol in Line 30

In summary, you are having trouble with the following VHDL code:You are having trouble with the following VHDL code:
  • #1
Dinosaur
4
0
I'm having trouble with the following VHDL code:

Code:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity circuit is
	port (a, b, c: in std_logic;
		f1, f2, f3, f4, f5, f6: out std_logic);
end circuit;

architecture Structural of circuit is
	component NOT1
		port(in1, in2, in3, in4: in std_logic;
			out1, out2, out3, out4: out std_logic);
	end component;

	component AND1
		port(in1, in2, in3, in4, in5, in6, in7, in8: in std_logic;
			out1, out2, out3, out4: out std_logic);
	end component;
	
	component OR1
		port(in1, in2, in3, in4, in5, in6, in7, in8: in std_logic;
			out1, out2, out3, out4: out std_logic);
	end component;  	
	
	signal anot, bnot, cnot, or3, or8, or11, and8, or6, and6 : std_logic;
begin
G0: NOT1	port map (in1 => a, out1 => anot, in2 => b, out2 => bnot, in3 => or3, out3 => f1, in4 => or3, out4 => f4);
G1: AND1	port map (in1 => c, in2 => or11, out1 = f3, in3 => a, in4 => bnot, out2 => and8, in5 => a, in6 => or6, out3 => f2, in7 => anot, in8 => b, out4 => and6); 					   	
G2: OR1 	port map(in1 => and8, in2 => and6, out1 = or11, in3 => bnot, in4 => c, out2 => or8, in5 => anot, in6 => bnot, out3 => or3, in7 => bnot, in8 => c, out4 => or6);
end Structural;

The compiler says that 'out1' is an undefined symbol in line 30 (G1). I have each gate defined separately, and all port definitions match between the gates and the whole circuit. The individual gates run with no problems, so I don't understand why the program chokes when I try to string them together. Renaming the outputs in G1 and the AND gate have no effect. I'd appreciate any pointers on where I'm going wrong. Everything's fine when I comment out G1 and G2.
 
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  • #2
Sorry, but I've been preoccupied for the last couple of weeks, and didn't see this. I'm sure you've figured it out by now, but your oversight was a simple typographical one. In your code:

begin
G0: NOT1 port map (in1 => a, out1 => anot, in2 => b, out2 => bnot, in3 => or3, out3 => f1, in4 => or3, out4 => f4);
G1: AND1 port map (in1 => c, in2 => or11, out1 = f3, in3 => a, in4 => bnot, out2 => and8, in5 => a, in6 => or6, out3 => f2, in7 => anot, in8 => b, out4 => and6);
G2: OR1 port map(in1 => and8, in2 => and6, out1 = or11, in3 => bnot, in4 => c, out2 => or8, in5 => anot, in6 => bnot, out3 => or3, in7 => bnot, in8 => c, out4 => or6);
end Structural;

You have a couple of simple of instantiation errors. You might try a couple of tricks to make it a bit easier, especially if you use particular components over and over. There is a different way to assign input signals, using the "port map" construct, than with the {=>} construct. This is to put the signals into the "port map" construct in the order in which they were originally assigned, simply separated by commas. Thus the trick is to simply copy the original "port" statement, paste it into a backup area (say on a Notepad screen), and there remove all but the original port representations and their commas. Then everytime that component is used, copy the part in parentheses back into the "port map" construct, and overlay each input port representation with the name of the signal that goes there.

Thus, as an example, if we take the device "AND1" and copy it and paste, we get:

port(in1, in2, in3, in4, in5, in6, in7, in8: in std_logic;
out1, out2, out3, out4: out std_logic);


Removing that not needed, we have:

(in1, in2, in3, in4, in5, in6, in7, in8, out1, out2, out3, out4)
Then, when we replace the port names with the signals to them, in the "port map" statement, we get:

G1: AND1 port map(in1, in2, in3, in4, in5, in6, in7, in8, out1, out2, out3, out4);

which becomes:

G1: AND1 port map(c, or11, a, bnot, a, or6, anot, b, f3, and8, f2, and6);

Note that, all signals must be in the correct order.
 
  • #3
Yup, I got it. Thanks for the help!
 

1. What does it mean when a VHDL circuit has an undefined symbol in line 30?

An undefined symbol in line 30 of a VHDL circuit means that there is a variable, signal, or component that has not been declared or initialized properly. This can cause errors in the operation of the circuit and must be resolved before the circuit can function correctly.

2. How do I troubleshoot an undefined symbol in line 30 of a VHDL circuit?

To troubleshoot an undefined symbol in line 30 of a VHDL circuit, you should first check all declarations and ensure that all variables, signals, and components have been properly declared and initialized. You should also check for any typos or misspelled names in the code. If the issue persists, it may be helpful to review the entire circuit and check for any other potential errors.

3. Can an undefined symbol in line 30 of a VHDL circuit cause the circuit to not work?

Yes, an undefined symbol in line 30 of a VHDL circuit can cause the circuit to not work properly. This is because the circuit relies on all variables, signals, and components being properly declared and initialized in order to function correctly.

4. How can I avoid an undefined symbol in line 30 when designing a VHDL circuit?

To avoid an undefined symbol in line 30 when designing a VHDL circuit, it is important to carefully plan and organize the code. This includes properly declaring and initializing all variables, signals, and components, as well as checking for any potential typos or misspelled names. It may also be helpful to review the code and troubleshoot any potential issues before running the circuit.

5. Are there any tools or resources available to help troubleshoot an undefined symbol in line 30 of a VHDL circuit?

Yes, there are various tools and resources available to help troubleshoot an undefined symbol in line 30 of a VHDL circuit. These include online forums and communities where you can ask for assistance, as well as debugging tools and simulators that can help identify and resolve errors in the code. It may also be helpful to consult with other experienced VHDL designers for guidance.

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