题解 | #信号发生器#

`timescale 1ns/1ns
module signal_generator(
	input clk,
	input rst_n,
	input [1:0] wave_choise,
	output reg [4:0]wave
	);
//方波的周期是20，锯齿波的周期是21，三角波的周期是40，且wave的最大值是20。
reg [4:0]cntf;
reg [4:0]cntj;
reg [4:0]cnts;
reg flag;
//assign flag=(wave==0 || wave==5'd20)?~flag:flag;
always@(posedge clk or negedge rst_n)begin
  if(!rst_n)
  cntf<=5'b0;
  else if(cntf>=20-1) 
  cntf<=5'b0;
  else 
  cntf<=cntf+1;
  end


always@(posedge clk or negedge rst_n) begin
  if(!rst_n)
  wave<=5'b0;
  else if (wave_choise==0) begin
        wave <= cntf<9?0:cntf<19?20:0;
  end 
  else if(wave_choise==1)begin
  wave<=cntj;
  end
 else if(wave_choise==2)begin
    wave <= flag==0 ? wave-1: wave+1;
  
 end
	    
       
  
end

always@(posedge clk or negedge rst_n)begin
  if(!rst_n)
  cntj<=5'b0;
  else if(wave_choise==1) begin
  if(cntj>=21-1) 
  cntj<=5'b0;
  else 
  cntj<=cntj+1;
  end
  end





always@(posedge clk or negedge rst_n)begin
  if(!rst_n)
  cnts<=5'b0;
  else if(cnts>=20-1) 
  cnts<=5'b0;
  else 
  cnts<=cnts+1;
  
  end

reg flag1;



always @(posedge clk or negedge rst_n) begin
    if (~rst_n) begin
        flag <= 0;
    end else begin
        if (wave_choise != 2) begin
            flag <= 0;
        end else begin
            if (wave == 1) begin
                flag <= 1;
            end else if (wave == 19) begin
                flag <= 0;
            end else begin
                flag <= flag;  // 保持 flag 不变
            end
        end
    end
end
  
  



endmodule