接上一节https://blog.csdn.net/pxy198831/article/details/87017571

TMS320C5509A 控制DDS AD9854芯片进行AM幅度调制

话音信号处理都少不了要用滤波，一般用FIR滤波比较多，

5509有数学LIB库可以直接调用，但是参数需要MATLAB生成。

程序如下：

fir((DATA *)&I_Q_result, (DATA *)B_BS,(DATA *)&I_Q_result, BS_dbuf,1,BL_BS);

相关的定义如下


int I_Q_result;
typedef short DATA;

#pragma DATA_SECTION(BP_dbuf,".globe_para");
DATA BP_dbuf[300];

#pragma DATA_SECTION(BP_dbuf_out,".globe_para");
DATA BP_dbuf_out[300];

#pragma DATA_SECTION(BS_dbuf,".globe_para");
DATA BS_dbuf[400];

在CMD文件中（见https://blog.csdn.net/pxy198831/article/details/86582628DSP TMS320C5509A之初始化（二））

.globe_para : {}> DARAM2 PAGE 0

然后是关键的FIR参数，用MATLAB的FDATOOLS生成

根据需要选择合适的FIR滤波器数学模型，选择BANDPASS，带通，音频信号根据需要选择高低频率截止点和带内不平度，观察实际的频响，选择合适的阶数。采样率FS根据AD的采样率设置为44.1KHz

然后生成C头文件。

单击上图中的"Target" 下面的“generate C header” ，选择生成int型参数如下：

/*
 * Filter Coefficients (C Source) generated by the Filter Design and Analysis Tool
 *
 * Generated by MATLAB(R) 7.0 and the 
 *
 * Generated on: 06-May-2015 14:38:08
 *
 */

/*
 * Discrete-Time FIR Filter (real)
 * -------------------------------
 * Filter Structure  : Direct-Form FIR
 * Filter Order      : 300
 * Stable            : Yes
 * Linear Phase      : Yes (Type 1)
 */

/* General type conversion for MATLAB generated C-code  */
#include "tmwtypes.h"
/* 
 * Expected path to tmwtypes.h 
 * D:\MATLAB7\extern\include\tmwtypes.h 
 */
/*
 * Warning - Filter coefficients were truncated to fit specified data type.  
 *   The resulting response may not match generated theoretical response.
 *   Use the Filter Design & Analysis Tool to design accurate fixed-point
 *   filter coefficients.
 */
const int BL_BS = 301;
const int16_T B_BS[301] = {
        3,      4,      6,      7,      6,      5,      3,      1,      0,
        0,      2,      5,      9,     12,     13,     12,     10,      6,
        1,     -1,     -1,      2,      7,     13,     19,     21,     20,
       15,      7,      0,     -6,     -7,     -3,      6,     16,     24,
       29,     27,     19,      6,     -7,    -16,    -19,    -14,     -2,
       13,     27,     33,     31,     19,      0,    -20,    -36,    -41,
      -35,    -19,      3,     22,     33,     30,     13,    -14,    -44,
      -67,    -78,    -71,    -50,    -19,      9,     26,     24,      2,
      -36,    -79,   -114,   -131,   -125,    -96,    -54,    -13,     13,
       13,    -15,    -66,   -125,   -176,   -203,   -197,   -160,   -102,
      -44,     -4,      2,    -32,    -99,   -180,   -253,   -293,   -290,
     -241,   -162,    -77,    -16,     -1,    -41,   -128,   -240,   -343,
     -405,   -406,   -341,   -230,   -106,    -10,     24,    -22,   -139,
     -297,   -449,   -548,   -559,   -472,   -308,   -116,     43,    115,
       66,   -101,   -344,   -594,   -771,   -810,   -684,   -415,    -72,
      241,    418,    378,     97,   -376,   -926,  -1389,  -1594,  -1404,
     -755,    317,   1679,   3118,   4388,   5258,   5568,   5258,   4388,
     3118,   1679,    317,   -755,  -1404,  -1594,  -1389,   -926,   -376,
       97,    378,    418,    241,    -72,   -415,   -684,   -810,   -771,
     -594,   -344,   -101,     66,    115,     43,   -116,   -308,   -472,
     -559,   -548,   -449,   -297,   -139,    -22,     24,    -10,   -106,
     -230,   -341,   -406,   -405,   -343,   -240,   -128,    -41,     -1,
      -16,    -77,   -162,   -241,   -290,   -293,   -253,   -180,    -99,
      -32,      2,     -4,    -44,   -102,   -160,   -197,   -203,   -176,
     -125,    -66,    -15,     13,     13,    -13,    -54,    -96,   -125,
     -131,   -114,    -79,    -36,      2,     24,     26,      9,    -19,
      -50,    -71,    -78,    -67,    -44,    -14,     13,     30,     33,
       22,      3,    -19,    -35,    -41,    -36,    -20,      0,     19,
       31,     33,     27,     13,     -2,    -14,    -19,    -16,     -7,
        6,     19,     27,     29,     24,     16,      6,     -3,     -7,
       -6,      0,      7,     15,     20,     21,     19,     13,      7,
        2,     -1,     -1,      1,      6,     10,     12,     13,     12,
        9,      5,      2,      0,      0,      1,      3,      5,      6,
        7,      6,      4,      3
};

TMS320C5509A 控制DDS AD9854芯片进行AM幅度调制时的FIR滤波处理

TMS320C5509A 控制DDS AD9854芯片进行AM幅度调制

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