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sin_cal.c
sin_cal.h
生成波形
一阶滤波器
FirstOrderFilter.c
FirstOrderFilter.h
测试
低通滤波器
高通滤波器
IAP15W4K58S4
Keil uVision V5.29.0.0
PK51 Prof.Developers Kit Version:9.60.0.0
串口示波器：Vofa+ 1.3.10
低通滤波器
见
一阶RC低通滤波器的数学模型及算法实现 —— 奔跑的chanchanchan
高通滤波器
见
一阶RC高通滤波器详解（仿真+matlab+C语言实现）—— 小麦大叔
#include "sin_cal.h"
#include <math.h>
void sin_Init(sin_Type *Sin, float f, float delta_ms)
Sin->angle = 0;
Sin->delta = 2 * 3.141592653589793f * f * delta_ms / 1000.f;
Sin->out = 0;
float sin_cal(sin_Type *Sin)
Sin->angle += Sin->delta;
if (Sin->angle > 6.283185307179586f)
Sin->angle -= 6.283185307179586f;
Sin->out = sin(Sin->angle);
return Sin->out;
#ifndef __SIN_CAL_H__
#define __SIN_CAL_H__
typedef struct
float angle;
float delta;
float out;
} sin_Type;
void sin_Init(sin_Type *Sin, float f, float delta_ms); //f为设定的频率，delta_ms为时间间隔
float sin_cal(sin_Type *Sin);
#endif
//...
sin_Type Sin_1, Sin_2;
//...
sin_Init(&Sin_1, 1, 5); //1 Hz的正弦波
sin_Init(&Sin_2, 25, 5); //25 Hz的正弦波
//...
定时器中断周期为1ms，每5ms输出一次数据
extern sin_Type Sin_1, Sin_2;
/********************* Timer0中断函数************************/
void timer0_int (void) interrupt TIMER0_VECTOR
static int count = 0;
float Data;
if(++count >= 5)
count = 0;
sin_cal(&Sin_1);
sin_cal(&Sin_2);
Data = Sin_1.out+Sin_2.out;
printf("%f\r\n", Data);
如图，生成了1Hz和25Hz的混合波形：
#include "FirstOrderFilter.h"
void fof_Init(fof_Type *fof, float f, float delta_ms, char HPForLPF)
fof->in_old = 0;
fof->out = 0;
fof->type = HPForLPF;
fof->a = 2 * 3.141592653589793f * f * delta_ms / 1000.f;
if(!HPForLPF)
fof->a = 1.f / fof->a;
fof->a = 1.f / (1.f + fof->a);
float FirstOrderFilter(fof_Type *fof, float in)
if(fof->type)
fof->out = fof->a * fof->out + fof->a * (in - fof->in_old);
fof->in_old = in;
fof->out = fof->a * in + (1 - fof->a) * fof->out;
return fof->out;
#ifndef __FOF_H__
#define __FOF_H__
typedef struct
float a;
float in_old;
float out;
char type;
} fof_Type;
void fof_Init(fof_Type *fof, float f, float delta_ms, char HPForLPF); //f为截止频率，delta_ms为时间间隔，HPForLPF为类型选择
float FirstOrderFilter(fof_Type *fof, float in);
#endif
//...
fof_Type fof_1, fof_2;
//...
fof_Init(&fof_1, 1, 5, 0); //低通滤波器，截止频率为1Hz
fof_Init(&fof_2, 25, 5, 1); //高通滤波器，截止频率为25Hz
//...
extern fof_Type fof_1, fof_2;
extern sin_Type Sin_1, Sin_2;
/********************* Timer0中断函数************************/
void timer0_int (void) interrupt TIMER0_VECTOR
static int count = 0;
float Data;
if(++count >= 5)
count = 0;
sin_cal(&Sin_1);
sin_cal(&Sin_2);
Data = Sin_1.out+Sin_2.out;
printf("%f, %f, %f\r\n", Data, FirstOrderFilter(&fof_1, Data), FirstOrderFilter(&fof_2, Data));
下图为滤波效果
截止频率外的25Hz的信号经滤波已衰减至0.040
高通滤波器
截止频率外的1Hz的信号经滤波已衰减至0.039
