P6-58 8bit Gray change into Binary code適用於DE2-70

P6-58 8bit Gray change into Binary code適用於DE2-70

源自於http://verticalhorizons.in/binary-to-gray-code-converter-gray-to-binary-code-converter/

Binary To Gray Code Converter – Gray to Binary Code Converter

The conversion between gray to binary and binary to gray is very common in digital systems. In one of our previous post we explained what are gray codes and how to convert from binary to gray and gray to binary. This post focus on implementing code converter using logic gates.

Binary to Gray Code Converter

Gray code equivalent of the given binary number is computed as follows:

g₃ = b₃
g₂ = b₃ ⊕ b₂
g₁ = b₂ ⊕ b₁
g₀ = b₁ ⊕ b₀

A binary to gray code converter can be implemented using XORgates. For n input, n-1 gates are required. As shown in the image below for 4 inputs, 3 XOR gates are used:

Gray to Binary Code Converter

Binary code equivalent of the given gray number is computed as follows:

b₃ = g₃
b₂ = b₃ ⊕ g₂
b₁ = b₂ ⊕ g₁
b₀ = b₁ ⊕ g₀

A gray to binary code converter can be implemented using XORgates. For n input, n-1 gates are required. As shown in the image below for 4 inputs, 3 XOR gates are used:

//--------------------------------------

//Convert 8-bit Gray code to binary code 

//using for loop

//filename : gra2bin.v

//--------------------------------------

module gray2bin(SW, LEDR, LEDG , CLOCK_27 ,KEY ,HEX0 ,HEX1 ,HEX2,HEX3 );

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 [7:0] LEDG; // green LEDs

    

    output [6:0] HEX0,HEX1,HEX2,HEX3; //7-segment display

    parameter length = 8;       //8-bit length

  

//set original program input , output 

//bin2gra(Gry, Bin);

//output [length-1:0] Gry;    //Gray code putput

//input [length-1:0] Bin;     //Binary input

reg  [length-1:0] Bin;

wire [length-1:0] Gry;

    

        

    //mapping to hardware 

    assign LEDR = SW;

    assign Gry=SW[7:0];

    

integer i;

always @ (Gry)

begin

Bin[length-1]=Gry[length-1]; 

for (i=length-2; i>=0; i = i-1)

Bin[i]=Bin[i+1] ^ Gry[i];

end

    

    assign LEDG[7:0]=Bin;

endmodule