8:3 Encoder

Theory:

The 8 to 3 line Encoder is also known as Octal to Binary Encoder. In 8 to 3 line encoder, there is a total of eight inputs, i.e., Y0, Y1, Y2, Y3, Y4, Y5, Y6, and Y7 and three outputs, i.e., A0, A1, and A2. In 8-input lines, one input-line is set to true at a time to get the respective binary code in the output side. Below are the block diagram and the truth table of the 8 to 3 line encoder.

BOOLEAN EXPRESSION FOR 8X3 ENCODER :

A2=Y4+Y5+Y6+Y7 A1=Y2+Y3+Y6+Y7 A0=Y7+Y5+Y3+Y1

Verilog code:

module encoder_8_3( input[7:0]in, output reg[2:0]out ); always@(in) begin

if(in[7]==1)

out=3'b111;

else if(in[6]==1) out=3'b110;

else if(in[5]==1) out=3'b101;

else if(in[4]==1) out=3'b100;

else if(in[3]==1) out=3'b011;

else if(in[2]==1) out=3'b010;

else if(in[1]==1)

out=3'b001;

else

out=3'b000; end endmodule

Test bench:

module testbench; reg [7:0] in; wire [2:0] out;

encoder_8_3

dut(.in(in), .out(out));

Initial begin

#0 in=8'b10000000;

#10 in=8'b01000000;

#10 in=8'b00100000;

#10 in=8'b00010000;

#10 in=8'b00001000;

#10 in=8'b00000100;

#10 in=8'b00000010;

#10 in=8'b00000001;

#10 in=8'b00000000;

end

initial

begin $monitor("in: %b out: %b ",in, out);

#100 $finish; end endmodule

output: