【Launchpad 心得】launchpad课后练习十六之软件滤波

常见泽1

【Launchpad 心得】launchpad课后练习十六之软件滤波 [复制链接]

launchpad课后练习十六之软件滤波

 

本文参考的《匠人笔记》里的十种软件滤波方法，这里只是滤波的简单介绍，不一定合理，高手绕道。版权属于《匠人笔记》

 

这里选用了其中的5种做了编程与测试，测试结果还算比较稳定与准确。当然滤波方法还有很多很多，下面只是其中的一部分而已。

 

本人也是初学者，里面难免有不合理之处，还望多多指教。

 

 

原理图

 

课后练习十六之ADC软件滤波.pdf (215.99 KB, 下载次数: 284)

2012-6-11 15:49 上传

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[ 本帖最后由 常见泽1 于 2012-6-11 15:56 编辑 ]

常见泽1

 限幅滤波法（又称程序判断滤波法）

　　 A、方法：

　　　   根据经验判断，确定两次采样允许的最大偏差值（设为A）

　　　　每次检测到新值时判断：

　　　　如果本次值与上次值之差<=A,则本次值有效

　　　　如果本次值与上次值之差>A,则本次值无效,放弃本次值,用上次值代替本次值

　　B、优点：

　　　　能有效克服因偶然因素引起的脉冲干扰

　　C、缺点

　　　　无法抑制周期性的干扰

　　　　平滑度差

 

1. #include <msp430g2452.h>
   #define uchar unsigned char
   #define uint unsigned int
   #define A 2
   unsigned char i,j;
   long result[31],resultsum,resultend;
   uchar ge,shi,bai,qian;
   
   #define SER ( 1 << 1 ) //也是所谓的DS
   #define SRCLK ( 1 << 0 ) //也是所谓的SHCP
   #define RCLK ( 1 << 2 ) //也是所谓的STCP
   
   void delay_1ms(void)
   {
   unsigned int i;
   for (i=0;i<1000;i++);
   }
   void delay_nms(unsigned int n)
   {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1ms();
   }
   
   uchar table[]={ 0xC0,0xF9,0xA4,0xB0,
   0x99,0x92,0x82,0xF8,
   0x80,0x90,0x88,0x83,
   0xC6,0xA1,0x86,0x8E };
   void Write595(uchar data)
   {
   
   P2OUT &= ~RCLK;
   for( i=0;i<8;i++ )
   {
   if(data&0x80)
   {
   P2OUT |= SER;
   }
   else
   {
   P2OUT &= ~SER;
   }
   P2OUT &= ~SRCLK;
   P2OUT |= SRCLK;
   data <<= 1;
   }
   P2OUT |= RCLK;
   }
   
   void ADC_init(void)
   {
   P1SEL |= 0x01;
   ADC10CTL0 = SREF_1 + REFON + ADC10ON;
   ADC10AE0 |= 0x01; // P1.0 ADC option select
   ADC10CTL1 = INCH_0+ADC10SSEL_2;
   }
   
   void main(void)
   {
   WDTCTL = WDTPW + WDTHOLD; // Stop WDT
   P1DIR |= (BIT2|BIT3|BIT4|BIT5);
   P2DIR |= 0xff;
   ADC_init();
   for(j=0;j<31;j++)
   {
   ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
   while (ADC10CTL1 & ADC10BUSY); // ADC10BUSY?
   result[j] = ADC10MEM;
   if(j>=2)
   {
   if((result[j] - result[j-1]>A)||(result[j-1] - result[j]>A))
   resultsum = result[j-1];
   else
   resultsum = result[j];
   }
   }
   
   while(1)
   {
   //result = resultsum/30;
   resultend = resultsum*1500/1024;
   qian = resultend/1000;
   bai = resultend/100%10;
   shi = resultend/10%10;
   ge = resultend%10;
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[ge]);
   P1OUT |= ( 1 << 2 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[shi]);
   P1OUT |= ( 1 << 3 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[bai]);
   P1OUT |= ( 1 << 4 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[qian]);
   P1OUT |= ( 1 << 5 );
   delay_nms(1);
   }
   }
   

复制代码

常见泽1

第2种：中位值滤波法

　　A、方法：

　　　　连续采样N次（N取奇数）

　　　　把N次采样值按大小排列

　　　　取中间值为本次有效值

　　B、优点：

　　　　能有效克服因偶然因素引起的波动干扰

　　　　对温度、液位的变化缓慢的被测参数有良好的滤波效果

　　C、缺点：

　　　　对流量、速度等快速变化的参数不宜

 

1. #include <msp430g2452.h>
   #define uchar unsigned char
   #define uint unsigned int
   #define X 31
   unsigned char i,j,k;
   long resultsum,temp;
   uint result[31];
   uchar ge,shi,bai,qian;
   
   #define SER ( 1 << 1 ) //也是所谓的DS
   #define SRCLK ( 1 << 0 ) //也是所谓的SHCP
   #define RCLK ( 1 << 2 ) //也是所谓的STCP
   
   void delay_1ms(void)
   {
   unsigned int i;
   for (i=0;i<1000;i++);
   }
   void delay_nms(unsigned int n)
   {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1ms();
   }
   
   uchar table[]={ 0xC0,0xF9,0xA4,0xB0,
   0x99,0x92,0x82,0xF8,
   0x80,0x90,0x88,0x83,
   0xC6,0xA1,0x86,0x8E };
   void Write595(uchar data)
   {
   
   P2OUT &= ~RCLK;
   for( i=0;i<8;i++ )
   {
   if(data&0x80)
   {
   P2OUT |= SER;
   }
   else
   {
   P2OUT &= ~SER;
   }
   P2OUT &= ~SRCLK;
   P2OUT |= SRCLK;
   data <<= 1;
   }
   P2OUT |= RCLK;
   }
   
   void ADC_init(void)
   {
   P1SEL |= 0x01;
   ADC10CTL0 = SREF_1 + REFON + ADC10ON;
   ADC10AE0 |= 0x01; // P1.0 ADC option select
   ADC10CTL1 = INCH_0+ADC10SSEL_2;
   }
   
   void main(void)
   {
   WDTCTL = WDTPW + WDTHOLD; // Stop WDT
   P1DIR |= (BIT2|BIT3|BIT4|BIT5);
   P2DIR |= 0xff;
   ADC_init();
   for(j=0;j<X;j++)
   {
   ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
   while (ADC10CTL1 & ADC10BUSY); // ADC10BUSY?
   result[j]= ADC10MEM;
   }
   
   for(j=0;j<X-1;j++)
   {
   for(k=0;k<X-j;k++)
   {
   if(result[k]>result[k+1])
   {
   temp = result[k];
   result[k] = result[k+1];
   result[k+1] = temp;
   }
   }
   }
   
   while(1)
   {
   //result = resultsum/30;
   //result = result*1500/1024;
   resultsum = result[(X-1)/2];
   resultsum = resultsum*1500/1024;
   qian = resultsum/1000;
   bai = resultsum/100%10;
   shi = resultsum/10%10;
   ge = resultsum%10;
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[ge]);
   P1OUT |= ( 1 << 2 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[shi]);
   P1OUT |= ( 1 << 3 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[bai]);
   P1OUT |= ( 1 << 4 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[qian]);
   P1OUT |= ( 1 << 5 );
   delay_nms(1);
   }
   }
   

复制代码

常见泽1

算术平均滤波法

　　A、方法：

　　　　连续取N个采样值进行算术平均运算

　　　　N值较大时：信号平滑度较高，但灵敏度较低

　　　　N值较小时：信号平滑度较低，但灵敏度较高

　　　　N值的选取：一般流量，N=12；压力：N=4

　　B、优点：

　　　　适用于对一般具有随机干扰的信号进行滤波

　　　　这样信号的特点是有一个平均值，信号在某一数值范围附近上下波动

　　C、缺点：

　　　　对于测量速度较慢或要求数据计算速度较快的实时控制不适用

　　　　比较浪费RAM

 

1. #include <msp430g2452.h>
   #define uchar unsigned char
   #define uint unsigned int
   
   unsigned char i,j;
   long result,resultsum;
   uchar ge,shi,bai,qian;
   
   #define SER ( 1 << 1 ) //也是所谓的DS
   #define SRCLK ( 1 << 0 ) //也是所谓的SHCP
   #define RCLK ( 1 << 2 ) //也是所谓的STCP
   
   void delay_1ms(void)
   {
   unsigned int i;
   for (i=0;i<1000;i++);
   }
   void delay_nms(unsigned int n)
   {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1ms();
   }
   
   uchar table[]={ 0xC0,0xF9,0xA4,0xB0,
   0x99,0x92,0x82,0xF8,
   0x80,0x90,0x88,0x83,
   0xC6,0xA1,0x86,0x8E };
   void Write595(uchar data)
   {
   
   P2OUT &= ~RCLK;
   for( i=0;i<8;i++ )
   {
   if(data&0x80)
   {
   P2OUT |= SER;
   }
   else
   {
   P2OUT &= ~SER;
   }
   P2OUT &= ~SRCLK;
   P2OUT |= SRCLK;
   data <<= 1;
   }
   P2OUT |= RCLK;
   }
   
   void ADC_init(void)
   {
   P1SEL |= 0x01;
   ADC10CTL0 = SREF_1 + REFON + ADC10ON;
   ADC10AE0 |= 0x01; // P1.0 ADC option select
   ADC10CTL1 = INCH_0+ADC10SSEL_2;
   }
   
   void main(void)
   {
   WDTCTL = WDTPW + WDTHOLD; // Stop WDT
   P1DIR |= (BIT2|BIT3|BIT4|BIT5);
   P2DIR |= 0xff;
   ADC_init();
   for(j=0;j<31;j++)
   {
   ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
   while (ADC10CTL1 & ADC10BUSY); // ADC10BUSY?
   if(j!=0)
   {
   resultsum += ADC10MEM;
   }
   }
   
   while(1)
   {
   result = resultsum/30;
   result = result*1500/1024;
   qian = result/1000;
   bai = result/100%10;
   shi = result/10%10;
   ge = result%10;
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[ge]);
   P1OUT |= ( 1 << 2 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[shi]);
   P1OUT |= ( 1 << 3 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[bai]);
   P1OUT |= ( 1 << 4 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[qian]);
   P1OUT |= ( 1 << 5 );
   delay_nms(1);
   }
   }
   

复制代码

常见泽1

 

第四种：中位值平均滤波法（又称防脉冲干扰平均滤波法）

　　A、方法：

　　　　相当于“中位值滤波法”+“算术平均滤波法”

　　　　连续采样N个数据，去掉一个最大值和一个最小值

　　　　然后计算N-2个数据的算术平均值

　　　　N值的选取：3~14

　　B、优点：

　　　　融合了两种滤波法的优点

　　　　对于偶然出现的脉冲性干扰，可消除由于脉冲干扰所引起的采样值偏差

　　C、缺点：

　　　　测量速度较慢，和算术平均滤波法一样

　　　　比较浪费RAM

1. #include <msp430g2452.h>
   #define uchar unsigned char
   #define uint unsigned int
   #define X 31
   unsigned char i,j,k;
   long resultsum,temp,resultend;
   uint result[31];
   uchar ge,shi,bai,qian;
   
   #define SER ( 1 << 1 ) //也是所谓的DS
   #define SRCLK ( 1 << 0 ) //也是所谓的SHCP
   #define RCLK ( 1 << 2 ) //也是所谓的STCP
   
   void delay_1ms(void)
   {
   unsigned int i;
   for (i=0;i<1000;i++);
   }
   void delay_nms(unsigned int n)
   {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1ms();
   }
   
   uchar table[]={ 0xC0,0xF9,0xA4,0xB0,
   0x99,0x92,0x82,0xF8,
   0x80,0x90,0x88,0x83,
   0xC6,0xA1,0x86,0x8E };
   void Write595(uchar data)
   {
   
   P2OUT &= ~RCLK;
   for( i=0;i<8;i++ )
   {
   if(data&0x80)
   {
   P2OUT |= SER;
   }
   else
   {
   P2OUT &= ~SER;
   }
   P2OUT &= ~SRCLK;
   P2OUT |= SRCLK;
   data <<= 1;
   }
   P2OUT |= RCLK;
   }
   
   void ADC_init(void)
   {
   P1SEL |= 0x01;
   ADC10CTL0 = SREF_1 + REFON + ADC10ON;
   ADC10AE0 |= 0x01; // P1.0 ADC option select
   ADC10CTL1 = INCH_0+ADC10SSEL_2;
   }
   
   void main(void)
   {
   WDTCTL = WDTPW + WDTHOLD; // Stop WDT
   P1DIR |= (BIT2|BIT3|BIT4|BIT5);
   P2DIR |= 0xff;
   ADC_init();
   for(j=0;j<X;j++)
   {
   ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
   while (ADC10CTL1 & ADC10BUSY); // ADC10BUSY?
   result[j]= ADC10MEM;
   }
   
   for(j=0;j<X-1;j++)
   {
   for(k=0;k<X-j;k++)
   {
   if(result[k]>result[k+1])
   {
   temp = result[k];
   result[k] = result[k+1];
   result[k+1] = temp;
   }
   }
   }
   for(j=1;j<30;j++)
   {
   resultsum += result[j];
   }
   
   while(1)
   {
   resultend = resultsum/29;
   resultend = resultend*1500/1024;
   //resultsum = result[(X-1)/2];
   //resultsum = resultsum*1500/1024;
   qian = resultend/1000;
   bai = resultend/100%10;
   shi = resultend/10%10;
   ge = resultend%10;
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[ge]);
   P1OUT |= ( 1 << 2 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[shi]);
   P1OUT |= ( 1 << 3 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[bai]);
   P1OUT |= ( 1 << 4 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[qian]);
   P1OUT |= ( 1 << 5 );
   delay_nms(1);
   }
   }
   

复制代码

常见泽1

 

第五种：加权递推平均滤波法

　　A、方法：

　　　　是对递推平均滤波法的改进，即不同时刻的数据加以不同的权

　　　　通常是，越接近现时刻的数据，权取得越大。

　　　　给予新采样值的权系数越大，则灵敏度越高，但信号平滑度越低

　　B、优点：

　　　　适用于有较大纯滞后时间常数的对象

　　　　和采样周期较短的系统

　　C、缺点：

　　　　对于纯滞后时间常数较小，采样周期较长，变化缓慢的信号

　　　　不能迅速反应系统当前所受干扰的严重程度，滤波效果差

1. #include <msp430g2452.h>
   #define uchar unsigned char
   #define uint unsigned int
   const int coefficient[10]= {1,2,3,4,5,6,7,8,9,10};
   const int coesum = 55;
   
   unsigned char i,j;
   long resultsum,resultend,resultsum1;
   unsigned int result[11];
   uchar ge,shi,bai,qian;
   
   #define SER ( 1 << 1 ) //也是所谓的DS
   #define SRCLK ( 1 << 0 ) //也是所谓的SHCP
   #define RCLK ( 1 << 2 ) //也是所谓的STCP
   
   void delay_1ms(void)
   {
   unsigned int i;
   for (i=0;i<1000;i++);
   }
   void delay_nms(unsigned int n)
   {
   unsigned int i=0;
   for (i=0;i<n;i++)
   delay_1ms();
   }
   
   uchar table[]={ 0xC0,0xF9,0xA4,0xB0,
   0x99,0x92,0x82,0xF8,
   0x80,0x90,0x88,0x83,
   0xC6,0xA1,0x86,0x8E };
   void Write595(uchar data)
   {
   
   P2OUT &= ~RCLK;
   for( i=0;i<8;i++ )
   {
   if(data&0x80)
   {
   P2OUT |= SER;
   }
   else
   {
   P2OUT &= ~SER;
   }
   P2OUT &= ~SRCLK;
   P2OUT |= SRCLK;
   data <<= 1;
   }
   P2OUT |= RCLK;
   }
   
   void ADC_init(void)
   {
   P1SEL |= 0x01;
   ADC10CTL0 = SREF_1 + REFON + ADC10ON;
   ADC10AE0 |= 0x01; // P1.0 ADC option select
   ADC10CTL1 = INCH_0+ADC10SSEL_2;
   }
   
   void main(void)
   {
   WDTCTL = WDTPW + WDTHOLD; // Stop WDT
   P1DIR |= (BIT2|BIT3|BIT4|BIT5);
   P2DIR |= 0xff;
   ADC_init();
   for(j=0;j<11;j++)
   {
   ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
   while (ADC10CTL1 & ADC10BUSY); // ADC10BUSY?
   result[j] = ADC10MEM;
   }
   for(j=0;j<10;j++)
   {
   result[j] = result[j+1];
   resultsum += result[j]*coefficient[j];
   }
   resultsum /= coesum;
   
   while(1)
   {
   //resultend = resultsum/30;
   resultend = resultsum*1500/1024;
   qian = resultend/1000;
   bai = resultend/100%10;
   shi = resultend/10%10;
   ge = resultend%10;
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[ge]);
   P1OUT |= ( 1 << 2 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[shi]);
   P1OUT |= ( 1 << 3 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[bai]);
   P1OUT |= ( 1 << 4 );
   delay_nms(1);
   
   P1OUT &= ~(( 1 << 2 )|(1<<3)|(1<<4)|(1<<5));
   Write595(table[qian]);
   P1OUT |= ( 1 << 5 );
   delay_nms(1);
   }
   }
   

复制代码

shasidaran

学习学习
我常用的还用一种新旧值对比的方法
新值 = 新值*a + 上一次值*（1-a）
效果看起来也不错

常见泽1

这个办法值得一试  a的取值应该是个讲究 0.5还是根据不同的改变