Question

Design a module that can perform a binary-coded decimal (BCD) addition. You have two 4-bit BCD (decimal digits 0 to 9) inputs “a” and “b” and an 8-bit output “x” which represents a two digit BCD number.

X [7:4] represents the upper BCD digits

X [3:0] represents the lower BCD digits

In the Verilog file, please code a BCD adder. It should follow the following format.

module bcd_adder( a,b,x );

input wire [3:0] a;

input wire [3:0] b;

output reg [7:0] x;

...

Answer 1

module bcd_adder(a, b, x);

input wire [3:0] a;
input wire [3:0] b;
output reg [7:0] x;

wire [7:0] sum;

wire [7:0] result;

assign sum = a + b;

assign result = (sum[3:0] > 4'b1001 || sum[4] == 1'b1)? (sum + 4'b0110) : sum;

always @ (result)
begin
x <= result;
end

//Simulated