Subversion Repositories eco32

//

// rcv.v -- serial line receiver

//

`timescale 1ns/10ps

`default_nettype none

module rcv(clk, reset, full, parallel_out, serial_in);

    input clk;

    input reset;

    output reg full;

    output [7:0] parallel_out;

    input serial_in;

  reg serial_p;

  reg serial_s;

  reg [3:0] state;

  reg [8:0] shift;

  reg [10:0] count;

  assign parallel_out[7:0] = shift[7:0];

  always @(posedge clk) begin

    serial_p <= serial_in;

    serial_s <= serial_p;

  end

  always @(posedge clk) begin

    if (reset == 1) begin

      state <= 4'h0;

      full <= 0;

    end else begin

      if (state == 4'h0) begin

        full <= 0;

        if (serial_s == 0) begin

          state <= 4'h1;

          count <= 651;

        end

      end else

      if (state == 4'hb) begin

        state <= 4'h0;

        full <= 1;

      end else begin

        if (count == 0) begin

          state <= state + 1;

          shift[8:0] <= { serial_s, shift[8:1] };

          count <= 1302;

        end else begin

          count <= count - 1;

        end

      end

    end

  end

endmodule