led_pio.v

这个是基于NIOS II的FPGA平台的一个CF卡的接口模块

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// synthesis translate_off
`timescale 1ns / 100ps
// synthesis translate_on
module led_pio (
                 // inputs:
                  address,
                  chipselect,
                  clk,
                  reset_n,
                  write_n,
                  writedata,

                 // outputs:
                  out_port
               );

  output  [  7: 0] out_port;
  input   [  1: 0] address;
  input            chipselect;
  input            clk;
  input            reset_n;
  input            write_n;
  input   [  7: 0] writedata;

  wire             clk_en;
  reg     [  7: 0] data_out;
  wire    [  7: 0] out_port;
  assign clk_en = 1;
  //s1, which is an e_avalon_slave
  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
          data_out <= 0;
      else if (chipselect && ~write_n && (address == 0))
          data_out <= writedata[7 : 0];
    end


  assign out_port = data_out;


endmodule