Monday, November 14, 2011

COUNTER USING AN FPGA

I have decided to implement a counter as a start for FPGA applications.

I wrote the following verilog code of a counter from 0 to 8 for my digital electronics class & thought it would be a great idea to implement it on an FPGA Board;



module counter (count, clk, reset);
output [8:0] count;
input clk, reset;

reg [8:0] count;
parameter tpd_reset_to_count = 3;
parameter tpd_clk_to_count   = 2;

function [8:0] increment;
input [8:0] val;
reg [3:0] i;
reg carry;
  begin
    increment = val;
    carry = 1'b1;
    /*
     * Exit this loop when carry == zero, OR all bits processed
     */
    for (i = 4'b0; ((carry == 4'b1) && (i <= 8));  i = i+ 4'b1)
       begin
         increment[i] = val[i] ^ carry;
         carry = val[i] & carry;
       end
  end      
endfunction

always @ (posedge clk or posedge reset)
  if (reset)
     count = #tpd_reset_to_count 8'h00;
  else
     count <= #tpd_clk_to_count increment(count);

endmodule

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