代码中的计数器设置是因为我的开发板的时钟是100MHZ的,也就是1秒完成了100_000_000次时钟信号,所以我设置计数器为100_000_000次。
也就是说,我让流水灯的变化周期为1 s。
counter == 32'd100_000_000
`timescale 1ns / 1ps
module flow_led(
clk,
reset,
led
);
input clk;
input reset;
output [7:0] led;
reg [7:0] led;
reg [31:0] counter;
reg [1:0] state;
always @(posedge clk or negedge reset)
begin
if(!reset)
begin
counter <= 32'd0;
end
else if ( counter == 32'd100_000_000) //change T
begin
counter <= 32'd0;
end
else
begin
counter <= counter + 32'd1;
end
end
always @(posedge clk or negedge reset)
begin
if(!reset)
begin
state <= 8'd0;
end
else if( counter == 32'd0 )
begin
state <= 1'd1;
end
else
begin
state <= 1'd0;
end
end
always @(posedge clk or negedge reset)
begin
if(!reset)
begin
led <= 8'b1111_1111;
end
else
begin
if(state == 1'd1)
begin
if(led == 8'b1111_1111)
begin
led <= 8'b0000_0001;
end
else if(led == 8'b1000_0000)
begin
led <= 8'b0000_0001;
end
else
begin
led <= led << 1'b1;
end
end
end
end
endmodule
若在波形仿真中,我们想让与模拟的时钟信号也是100MHZ,让流水灯的周期也为1s,那样的话仿真是跑不完的。
所以我们先修改刚刚的计数周期:
counter == 32'd1_000_000
仿真中让时钟周期为1000 ns
parameter T=1000;
这样就可以很轻松的看到流水灯全周期的波形图了。
`timescale 1ns/1ns
module sim_dev1();
parameter T=1000;
reg clk;
reg reset;
wire [7:0] led;
initial
begin
clk=1'b0;
reset=1'b0;
#(T+1) reset=1'b1;
end
always #(T/2) clk=~clk;
flow_led u1(
.clk(clk),
.reset(reset),
.led(led)
);
endmodule
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