Realization of FIR filter based on DSP C language

First, the output formula of the FIR filter is:

(If you can see the digital signal processing books, it's almost forgotten ...) ）

Assumption: The input signal is x (n) = sin (2*pi*f1*n/fs) + sin (2*pi*f2*n/fs)

The filter designed is a low-pass FIR filter using the Hamming window with a order of 10

You can use the Filter design tool in MATLAB to design the filter:

You can then create a C header file to obtain the desired value by designing the filter:

The C program of the FIR filter is as follows:

#include <stdio.h> #include <math.h>             #define PI    3.1415#define N                      //n is the order of the filter +1#define LEN   512int Inputdata[len];                   Assume that the length of the data is 512int outputdata[len];long int yn;                                Yn is int, the data in the operation may overflow, thus filtering fails const int B[n] = {166, 0, -1374, 0, 9453, 16279, 9453, 0, -1374, 0,  166}    //fir filter parameters, Generated by Matlab

void Main () {int f1,f2,fs,i,j;        int  *a;        f1=100;    Frequency component 1 (Hz) f2=300;    Frequency component 2 (Hz) fs=800;    Sampling frequency (Hz) for (i=0;n<len;n++) {            Inputdata[n]=sin (2*pi*f1*n/fs) + sin (2*pi*f2*n/fs);    Generate Signal        }for (j=0;j<len;j++)             //Filter by Formula {a=&inputdata[j];yn=0;                for (i=0;i<n;i++) {                     yn=yn+b[i]* (*a++);                }outputdata[j]=yn>>16;     Signal}while after filtering (1);}                

Run in a CCS environment and see the time and frequency domain graphs of inputdata and outputdata by graph (not here, tested in the school's experimental class ...) ）

Its cmd file is:

-e startmemory  {        page 0:         PARAM:  org = 3000h    len = 4000h        PAGE 1:                        daram:  org = 100h    len=4000h        }                                       sections{         . Text         : >       PARAM   PAGE 0          stack          : >       daram   Page 1         filter_vars: >       daram   page 1        . BSS   : >       daram   page 1        . Data  : >       Daram   PAGE 1        }

　　

Realization of FIR filter based on DSP C language