濾波效果如圖所示
直接上代碼
veilog源碼
module my_filter_us(
input clk,//200Mhz
input rst,
input pulse_in,
input[7:0] pulse_delay,//濾波數值輸入，單位us 1-100
output reg pulse_out=1
);
reg[19:0] cnt_delay=0;
reg[3:0] filter_satae=3;
wire[19:0] data;
assign data=pulse_delay*200;
reg[19:0] cnt_rst=0;
reg rst_n=0;
always @(posedge clk)
begin
if(cnt_rst<100000)
begin
cnt_rst<=cnt_rst+1;
end
else
begin
rst_n<=1;
end
end
always @(posedge clk or negedge rst_n)
begin
if(!rst_n)
begin
end
else
begin
case(filter_satae)
0: begin
if(pulse_out==0)
begin
filter_satae<=filter_satae+1;
end
else if(cnt_delay<data)
begin
if(pulse_in==0)
begin
cnt_delay<=cnt_delay+1;
end
else
begin
cnt_delay<=0;
//data<=pulse_delay*200;
end
end
else if(pulse_in==0)
begin
pulse_out<=0;
cnt_delay<=0;
end
end
1: begin
filter_satae<=filter_satae+1;
end
2: begin
if(pulse_out==1)
begin
filter_satae<=filter_satae+1;
end
else if(cnt_delay<data)
begin
if(pulse_in==1)
begin
cnt_delay<=cnt_delay+1;
end
else
begin
cnt_delay<=0;
//data<=pulse_delay*200;
end
end
else if(pulse_in==1)
begin
pulse_out<=1;
cnt_delay<=0;
end
end
3: begin
filter_satae<=0;
//data<=pulse_delay*200;
end
endcase
end
end
endmodule
仿真
`timescale 1ns/1ps
module my_filter_us_tb(
);
reg clk=0;
reg pulse_in=0;
reg [7:0]pulse_delay=10;
wire pulse_out;
my_filter_us u1(
.clk(clk),
.pulse_in(pulse_in),
.pulse_delay(pulse_delay),
.pulse_out(pulse_out)
);
initial begin
forever
begin
clk=0; #2 clk=1; #3;//200Mhz
end
end
initial begin
forever
begin
pulse_in=0; #60000;
pulse_in=0; #3000 pulse_in=1; #3000;
pulse_in=0; #3000 pulse_in=1; #3000;
pulse_in=0; #3000 pulse_in=1; #3000;
pulse_in=0; #3000 pulse_in=1; #3000;
pulse_in=1; #60000;
pulse_in=0; #3000 pulse_in=1; #3000;
pulse_in=0; #3000 pulse_in=1; #3000;
pulse_in=0; #3000; pulse_in=1; #3000;
pulse_in=0; #3000; pulse_in=1; #3000;
end
end
endmodule
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