HDLForBeginners_Examples/NexysBaseProject/src/eth_rst_gen.sv

`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date: 13.11.2021 14:32:12
// Design Name: 
// Module Name: eth_rst_gen
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//////////////////////////////////////////////////////////////////////////////////


module eth_rst_gen(
    input clk,
    input rst,
    output eth_clk_out,
    output eth_rst_out,
    output ETH_REFCLK,
    output ETH_RSTN
    );
    
    logic locked;
    logic eth_rst;
    logic eth_clk;
    
   
    // 50M clk gen
  clk_wiz_0 gen_50M
   (
    .clk_out1(eth_clk),         // output clk_out1
    .clk_out2(ETH_REFCLK),     // output clk_out2
    .reset(rst),            // input reset
    .locked(locked),           // output locked
    .clk_in1(clk));         // input clk_in1
    
    
    localparam WAIT_CYCLES_50M = 2000000; // 40ms
    logic [31:0] wait_counter_50M;
    
    // Generate output reset signals in 50M domain
    always_ff@(posedge eth_clk) begin
        // remain in reset until global reset is released
        if (rst) begin
            eth_rst <= 1;
            wait_counter_50M <= 0;
        end 
        else begin
            // PLL locked
            if (locked) begin
                // remain in rst till counter is done
                if (wait_counter_50M < WAIT_CYCLES_50M-1) begin
                    eth_rst <= 1;
                    wait_counter_50M <= wait_counter_50M + 1;
                end
                else begin
                    eth_rst <= 0;
                end 
            end
            // PLL not locked. Remain in reset until locked
            else begin
                eth_rst <= 1;
                wait_counter_50M <= 0;
                
                
            end
        end
    end
    
    assign ETH_RSTN = ~eth_rst;
    assign eth_clk_out = eth_clk;
    assign eth_rst_out = eth_rst;
    
endmodule