基于FPGA的频率测量_fpga测量信号的频谱幅度

正弦波由matlb产生；

clc;
clear all;
close all;
%Sin400hz.m程序清单
%设置系统参数
fi=400;					%输入信号的频率
Fs=8000;				%采样频率
L=10024;				%数据长度
N=10;					%量化位数
x=0:1/(100*fi):2/fi;
figure('name','sin(2*pi*fi*x)');
plot(x,sin(2*pi*fi*x));
title('sin(2*pi*fi*x)');
xlabel('x');
ylabel('sin');
%产生400hz正弦信号
t=0:1/Fs:(1/Fs)*(L-1);		%产生采样频率的时间序列
si=sin(2*pi*fi*t);  	
 
%归一化处理
f_s=si/max(abs(si));
%10bit量化
Q_s=round(f_s*(2^(N-1)-1));
 
%将生成的输入正弦信号数据，写入外部文本文件(din.txt)中
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%新建文本文件前，必须建好文件存放的目录文件夹，否则出现提示信息:
%??? Error using ==> fprintf
%Invalid file identifier
fid=fopen('D:\a_FPGA\frequency_measure\sim\din.txt','w');
for k=1:length(Q_s)
    B_s=dec2bin(Q_s(k)+(Q_s(k)<0)*2^N,N);
    for j=1:N
       if B_s(j)=='1'
           tb=1;
       else
           tb=0;
       end
       fprintf(fid,'%d',tb);  
    end
    fprintf(fid,'\r\n');
end
fprintf(fid,';'); 
fclose(fid);
 

Verilog源代码：

module frequency_measure(
	//input
	clk,//8000Hz;
	rst_n, //0 valid;
	data_in, 
	f
);
input clk,rst_n;
input [9:0] data_in;//10bit digital data;
output[9:0] f;	//frequency,unit is Hz;
//reg define
reg [6:0] cnt0,cnt1;//the count of input signal's period needs
reg [1:0] transfer;
//main code;
always @(posedge clk or negedge rst_n)
	if(!rst_n)
		transfer <= 2'b00;
	else 
		begin 
			transfer[0] <= data_in[9];
			transfer[1] <= transfer[0];
		end 
 
always @(posedge clk or negedge rst_n)
	if(!rst_n)	//if reset ,cnt  <= 0;
		begin
			cnt0 <= 7'b0;
		end 
	else		//not reset;
		begin
			if(transfer == 2'b01)	
				begin
					cnt1<= cnt0 + 1'b1 ;
					cnt0 <= 7'b0;
				end 
				
			else 
				cnt0 <= cnt0 + 1'b1;
		end 
assign f = 8000/cnt1; //
		
		
endmodule 

测试代码：

`timescale 1ns/1ns 
module tb_frequency_measure();
//clk period;
parameter clk_period = 125000;
//data length;
parameter data_num = 10000;
//input;
reg clk,rst_n;
reg [9:0] data_in;
//output;
wire [9:0] f;
 
//frequency_measure instance;
frequency_measure u0_frequency_measure(
	.clk(clk),
	.rst_n(rst_n),
	.data_in(data_in),
	.f(f)
);
//clk;
always #(clk_period/2) clk = ~clk;
//parameter
initial 
	begin
		clk = 1'b0;
		rst_n = 1'b0;
		
		#(5*clk_period) rst_n = 1'b1;	
        data_in = 10'd0;		
	end 
//read din.txt as data_in;
integer pattern;
reg [9:0] stim_data[1:data_num];
initial 
	begin 
		//din.txt and tb_frequency_measure.v must in a same folder;
		$readmemb("D:/a_FPGA/frequency_measure/sim/din.txt",stim_data);
		pattern = 0;
		repeat(data_num)
			begin
				pattern = pattern + 1;
				data_in = stim_data[pattern];
				#clk_period;
			end 
	end 
endmodule

仿真结果：

起始因复位不能得到完整的1个周期的计数，所以计数会不对，计数结果为8，频率为1000；后面的都是对的，计数为20，频率为400。

仅供学习。