reconfig_request_pio.v

nios下的lcd驱动开发源代码（仅供参考）

//Copyright (C) 1991-2004 Altera Corporation
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//support information, device programming or simulation file, and any other
//associated documentation or information provided by Altera or a partner
//under Altera's Megafunction Partnership Program may be used only to
//program PLD devices (but not masked PLD devices) from Altera.  Any other
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// synthesis translate_off
`timescale 1ns / 100ps
// synthesis translate_on
module reconfig_request_pio (
                              // inputs:
                               address,
                               chipselect,
                               clk,
                               reset_n,
                               write_n,
                               writedata,

                              // outputs:
                               bidir_port,
                               readdata
                            );

  inout            bidir_port;
  output           readdata;
  input   [  1: 0] address;
  input            chipselect;
  input            clk;
  input            reset_n;
  input            write_n;
  input            writedata;

  wire             bidir_port;
  wire             clk_en;
  reg              data_dir;
  wire             data_in;
  reg              data_out;
  wire             read_mux_out;
  reg              readdata;
  assign clk_en = 1;
  assign read_mux_out = ({1 {(address == 0)}} & data_in) |
    ({1 {(address == 1)}} & data_dir);

  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
          readdata <= 0;
      else if (clk_en)
          readdata <= read_mux_out;
    end


  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;
    end


  assign bidir_port = data_dir ? data_out : 1'bZ;
  assign data_in = bidir_port;
  always @(posedge clk or negedge reset_n)
    begin
      if (reset_n == 0)
          data_dir <= 0;
      else if (chipselect && ~write_n && (address == 1))
          data_dir <= writedata;
    end




endmodule