2 digit BCD Adder at Behavioral level Modeling 適用於DE2-70

2 digit BCD Adder 00+00+0=00 ~99+99+1=199

module _2digit_BCDAdder(SW, LEDR, LEDG , CLOCK_27 ,KEY ,HEX0 ,HEX1 ,HEX2,HEX3,,HEX4,HEX5,HEX6,HEX7 );
 input  [17:0] SW;   // toggle switches
 input  [7:0] KEY;       // Push bottom
 input  CLOCK_27;   //Clock 27MHz , 50Mhz

 output [17:0] LEDR;   // red  LEDS   
 output [8:0] LEDG;   // green LEDs
   
 output [6:0] HEX0,HEX1,HEX2,HEX3,HEX4,HEX5,HEX6,HEX7; //7-segment display

 reg [3:0] a1,a0;
 reg [3:0] b1,b0;
 reg cin;
 wire [3:0] S1,S0;
 wire C4,C8;

 wire [7:0] segout0;   //HEX 0
 wire [7:0] segout1;   //HEX 1
 wire [7:0] segout2;   //HEX 2

 assign LEDR[17:0]=SW[17:0];

 always@(SW)
 begin
  a0=SW[3:0];
  a1=SW[7:4];
  b0=SW[11:8];
  b1=SW[15:12];
  cin=SW[17];
 end 

 BCD_adder U0(a0,b0,cin,S0,C4);

 BCD_adder U1(a1,b1,C4,S1,C8); 



  //Display BCD Sum to 7-segment Display

    _7seg UUT0(.hex(S0),.seg(segout0));
    _7seg UUT1(.hex(S1),.seg(segout1));
    _7seg UUT2(.hex({3'b000,C8}),.seg(segout2));
    
           
 assign HEX0=segout0[6:0];
 assign HEX1=segout1[6:0];
 assign HEX2=segout2[6:0];

 assign HEX3=7'h7f; //Blank 7-segment 
 assign HEX4=7'h7f;
 assign HEX5=7'h7f; //Blank 7-segment 
 assign HEX6=7'h7f;
 assign HEX7=7'h7f;   //set 1 => off LED

endmodule 


module BCD_adder(a,b,cin,s,cout);
 input [3:0]a,b;
 input cin;
 output [3:0]s;
 output cout;

 reg [3:0]s,a_tmp,b_tmp;
 reg cout;
 reg [4:0]z;   //5bit Sum 

 always @ ( a or b )
  begin
   if (a>9)
    a_tmp= 4'b1001;   //若是>9 則為9
   else
    a_tmp=a;

   if (b>9)
    b_tmp = 4'b1001;   //若是>9 則為9
   else
    b_tmp=b; 
  end



 always@(a_tmp or b_tmp or cin)
  begin
   z=a_tmp+b_tmp+cin;
   if (z>9)
     {cout,s}=z+6;
   else
     {cout,s}=z;  

 end
endmodule




//-----------------------------------------
//Common-cathod seven segment display
//using case.....endcase statement
//Filename : sevenseg_case.v
//----------------------------------------- 
module _7seg(hex , seg);
    input  [3:0] hex;
    output [7:0] seg;
    reg    [7:0] seg;
 // segment encoding
 //      0
 //     ---  
 //  5 |   | 1
 //     ---   <- 6
 //  4 |   | 2
 //     ---
 //      3
 always @(hex)
 begin
  case (hex)
       // Dot point is always disable
       4'b0001 : seg = 8'b11111001;   //1 = F9H
       4'b0010 : seg = 8'b10100100;   //2 = A4H
       4'b0011 : seg = 8'b10110000;   //3 = B0H
       4'b0100 : seg = 8'b10011001;   //4 = 99H
       4'b0101 : seg = 8'b10010010;   //5 = 92H
       4'b0110 : seg = 8'b10000010;   //6 = 82H
       4'b0111 : seg = 8'b11111000;   //7 = F8H
       4'b1000 : seg = 8'b10000000;   //8 = 80H
       4'b1001 : seg = 8'b10010000;   //9 = 90H
       4'b1010 : seg = 8'b10001000;   //A = 88H
       4'b1011 : seg = 8'b10000011;   //b = 83H
       4'b1100 : seg = 8'b11000110;   //C = C6H
       4'b1101 : seg = 8'b10100001;   //d = A1H
       4'b1110 : seg = 8'b10000110;   //E = 86H
       4'b1111 : seg = 8'b10001110;   //F = 8EH
       default : seg = 8'b11000000;   //0 = C0H
     endcase
   end
   
endmodule