BCD Adder:
A 4-bit binary adder that is capable of adding two 4bit words having a BCD (binary-coded decimal) format. The result of the addition is a BCD-format 4-bit output word, representing the decimal sum of the addend and augend, and a carry that is generated if this sum exceeds a decimal value of 9.
We have implemented a 4-bit BCD adder using 1-bit full adder, AND, OR gate. Three inputs are taken as a, b, cin and three outputs are produced as sum, carry and cout.
Verilog Code for BCD Adder:
module bcd_adder(sum,cout,a,b,cin);
output
reg [3:0]sum;//4bit sum output.
output
reg cout;//carry output.
input
[3:0]a,b;//4bit input a and b.
input
cin;//carry input.
always@(*)
begin
sum=a+b+cin;//here
we are adding a , b and c .
if(sum>9)
begin//if sum is greater then we will add 6.
sum
= sum +6;
cout
= 1;//and carry become 1.
end
else
begin
cout
= 0;
sum
= sum;
end
end
endmodule
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