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Beginner
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help with coding 4bit adder on vhdl

I've been having trouble with coding this simple full adder on VHDL with structural coding more specifically using components

and here's my code :

Library ieee; use ieee.std_logic_1164.all;   Entity 4bfa is port( A : In std_logic_vector (3 downto 0); B : In std_logic_vector (3 downto 0); cin : in std_logic; cout: out std_logic; Sum : out std_logic_vector (3 downto 0) ); end 4bfa;   architecture my of 4bfa is cin := 0; signal c0,c1,c2,c3,s1,s2,s3,s4 : std_logic;   component fastructural is port ( I1,I2, ci: IN std_logic; co,s : out std_logic); end component;   begin u1 : fastructural port map( I1 => A(0), I2 => B(0), ci =>cin, co=>c0, s=>s1); u2 : fastructural port map( I1 => A(1), I2 => B(1), ci =>c0, co=>c1, s=>s2); u3 : fastructural port map( I1 => A(2), I2 => B(2), ci =>c1, co=>c2, s=>s3); u4 : fastructural port map( I1 => A(3), I2 => B(3), ci =>c2, co=>c3, s=>s4);   cout<=c3;   Sum<="s4&s3&s2&s1";   end my;

and he is the errors that I get :

Error (10500): VHDL syntax error at 4bfa.vhd(4) near text "4"; expecting an identifier   Error (10500): VHDL syntax error at 4bfa.vhd(11) near text "4"; expecting an identifier

Also for the fastructural componant is a componant of a full adder for one bit that I already have on another VHDL code and that works just fine.

but I still don't know what is the issue.

 

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2 Replies
Employee
33 Views

Hi,

Basically basic identifiers are used for naming design entities & basic identifier must begin with a letter so in this case entity name must start with letter like 'fa4b'.

 

Let me know if this has helped resolve the issue you are facing or if you need any further assistance.

 

Best Regards

Vikas Jathar 

(This message was posted on behalf of Intel Corporation)

 

Employee
33 Views

Hi,

Have you resolved the issue?

 

Best Regards

Vikas Jathar 

(This message was posted on behalf of Intel Corporation)

 

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