Question

求助单片机测频程序

我要编一个单片机测频程序，但是现在我不知道待测频率是多少，能不能用程序编一个外部输入信号到单片机T0，来验证我这个程序的正确性？
如果能的话，请问应当怎么做？谢谢！！！

Answer 1

单片机测频程序2006-09-25 17:38/* 单片机测频 程序 下到 20hz 上到 29k */
/*如果想要测更高频率可用模拟开关加分频器*/
/* 作者 赵亮、尹书扬*/

/* 时间：05-8-27 */

/*说明： 头文件中调用的“lcd1602.h”只需要把我发的lcd1602的子程序做一个h文件即可*/
＃i nclude "AT89X52.h"
＃i nclude "stdio.h"
＃i nclude " absacc.h "
＃i nclude <intrins.h>
＃i nclude <math.h>
＃i nclude "lcd1602.h"

sbit F_in=P1^0;

bit int_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
{
int_flag=1;
}

void Frequency_Measure(void)
{
if(frequency<2000)
Measure_T();
else if(frequency>=2000)
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(int_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)
{
temp_flag++;
TR0=1;
}
if(temp_flag==2)
{
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," ");
}

转自:http://hi.baidu.com/myso/blog/item/be82e7ddcb00baef76c638ac.html