mcu_measurefrequency.c

单片机测频程序 采用测频法和测周法进行等精度测量频率

#include "AT89X52.h" 
#include "stdio.h" 
#include " absacc.h " 
#include <intrins.h> 
#include <math.h> 
#include "lcd1602.h" 
sbit F_in=P1^0; 
bit T0int_flag; 
unsigned int frequency; 
void Display(void); 
void Mcu_init(void); 
void Measure_F(void); 
void Measure_T(void); 
void Frequency_Measure(void); 

void main() { 
  Mcu_init(); 
  while(1) { 
    Frequency_Measure();
    Display(); 
   } 
} 

void time0(void) interrupt 1 {
  T0int_flag=1;
} 

void Frequency_Measure(void) { 
  if(frequency<2000) Measure_T(); 
  else  Measure_F(); 
} 

void Measure_F(void) { 
  bit state_old=0,state_new=0; 
  unsigned int f_count=0;
  int_flag=0;
  TH0=-50000/256;
  TL0=-50000%256;
  TR0=1; 
  while(1) { 
    state_new=F_in; 
    if(state_old!=state_new) f_count++; 
    state_old=state_new; 
    if(T0int_flag) { 
      TR0=0; 
      frequency=f_count*10;
      return; 
     }
   } 
}

void Measure_T(void) { 
  bit state_old=0,state_new=0; 
  unsigned char temp_flag=0; 
  unsigned int t_count; 
  TH0=0; 
  TL0=0; 
  while(1) { 
    state_new=F_in; 
    if(state_old&&!state_new) {//下降沿计数
    temp_flag++; 
    TR0=1; 
  } 
  if(temp_flag==2) {//满一个周期后停止计数
    TR0=0; 
    t_count=TH0*256+TL0; 
    frequency=1000000/t_count; 
    return; 
  }
  state_old=state_new; 
  } 
}

void Display(void) { 
  unsigned char a,b,c,d,e; 
  a=frequency/10000; 
  b=frequency%10000/1000; 
  c=frequency%1000/100; 
  d=frequency%100/10; 
  e=frequency%10; 
  LCD_string(LINE1,0,"F-measure:"); 
  LCD_char(LINE1,0x0b,a|0x30); 
  LCD_char(LINE1,0x0c,b|0x30); 
  LCD_char(LINE1,0x0d,c|0x30); 
  LCD_char(LINE1,0x0e,d|0x30); 
  LCD_char(LINE1,0x0f,e|0x30); 
  if(frequency<2000) LCD_string(LINE2,0,"Now is measure T"); 
  else LCD_string(LINE2,0,"Now is measure F"); 
}

void Mcu_init(void) {
  EA=1; 
  ET0=1; 
  TR0=1; 
  TMOD=0x01; 
  TH0=-(50000/256); 
  TL0=-(50000%256); 
  LCD_init(); 
  LCD_string(LINE1,0x00," "); 
  LCD_string(LINE1,0x00," ");
}