Subversion Repositories s80186

// Copyright Jamie Iles, 2017

//

// This file is part of s80x86.

//

// s80x86 is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// s80x86 is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with s80x86.  If not, see .

module BaudRateGen #(parameter clk_freq = 50000000)

                    (input logic clk,

                     input logic reset,

                     output logic rxclk_en,

                     output logic txclk_en);

localparam RX_ACC_MAX = clk_freq / (115200 * 16);

localparam TX_ACC_MAX = clk_freq / 115200;

localparam RX_ACC_WIDTH = $clog2(RX_ACC_MAX);

localparam TX_ACC_WIDTH = $clog2(TX_ACC_MAX);

reg [RX_ACC_WIDTH - 1:0] rx_acc = 0;

reg [TX_ACC_WIDTH - 1:0] tx_acc = 0;

assign rxclk_en = (rx_acc == 5'd0);

assign txclk_en = (tx_acc == 9'd0);

always_ff @(posedge clk or posedge reset) begin

    if (reset) begin

        rx_acc <= {RX_ACC_WIDTH{1'b0}};

    end else begin

        if (rx_acc == RX_ACC_MAX[RX_ACC_WIDTH - 1:0])

            rx_acc <= {RX_ACC_WIDTH{1'b0}};

        else

            rx_acc <= rx_acc + 1'b1;

    end

end

always_ff @(posedge clk or posedge reset) begin

    if (reset) begin

        tx_acc <= {TX_ACC_WIDTH{1'b0}};

    end else begin

        if (tx_acc == TX_ACC_MAX[TX_ACC_WIDTH - 1:0])

            tx_acc <= {TX_ACC_WIDTH{1'b0}};

        else

            tx_acc <= tx_acc + 1'b1;

    end

end

endmodule