重温FPGA设计之bcd加法器verilog实现

1.题目

 2.源码

// *********************************************************************************
// Project Name : BCD_adder
// Email        : 2972880695@qq.com
// Website      : https://home.cnblogs.com/u/hqz68/
// Create Time  : 2019/12/11 
// File Name    : BCD_adder.v
// Module Name  : BCD_adder
// Abstract     :
// editor		: sublime text 3
// *********************************************************************************
// Modification History:
// Date         By              Version                 Change Description
// -----------------------------------------------------------------------
// 2019/12/11    宏强子           1.0                     Original
//  
// *********************************************************************************
`timescale      1ns/1ns	
module BCD_adder (
	input			[3:0]	a				, 
	input			[3:0]	b				,

	output	reg		[3:0]	sum				,
	output	reg				c 				
);

//========================================================================\
// =========== Define Parameter and Internal signals =========== 
//========================================================================/

reg		[4:0]		sum_r	;

//=============================================================================
//****************************     Main Code    *******************************
//=============================================================================
always @ (a or b) begin
		sum_r = a + b;        
end


always @ (sum_r) begin
		if (sum_r >4'd9) begin
			sum  = sum_r - 4'd10;
			c = 1'b1;
		end
		else begin
			sum = sum_r;
			c = 1'b0;
		end        
end

    
endmodule

3.测试平台

`timescale      1ns/1ns
module tb_bcd_adder();

reg		[3:0]	a 	;
reg		[3:0]	b 	;
wire	[3:0]	sum ;
wire			c	;



initial begin
	a = 4'd5;
	b = 4'd2;
	#100

	a = 4'd6;
	b = 4'd7;
	#100

	a = 4'd4;
	b = 4'd9;
	#100

	a = 4'd8;
	b = 4'd9;
	#100

	a = 4'd6;
	b = 4'd9;

end


 BCD_adder 	BCD_adder_inst(
	.a				(a 		), 
	.b				(b 		),

	.sum			(sum	),
	.c 				(c 		)
);

endmodule

4.仿真波形