测量频率的问题
马老师,你好。把你的那个测频率的程序移植到51单片机上面, 1KHz 以下的测的非常准,超过1K 就显示0 。请问这是什么原因?程序如下:void Init_Timer2(void) //捕获
{
T2CON=0X09;//设置T2为捕获模式,下降沿则产生中断
TH2=0;
TL2=0;
ET2=1; // 开定时器2
TR2=1;
}
void Timer2_isr(void) interrupt 5 using 1
{
if(EXF2)
{
if(icp_n >= max_icp)
{
icp_v2 = RCAP2L + (unsigned int)(RCAP2H << 8);
TR2=0;
icp_ok=1;
}
else if(icp_n == 0)
{
icp_v1 = RCAP2L + (unsigned int)(RCAP2H << 8);
}
icp_n++;
EXF2=0;
}
if(TF2)
{
T2_ovf=1;
TF2=0;
}
}
void calc_F(void)
{
if(icp_ok == 1)
{
if(icp_v2 >= icp_v1)
icp_2 = icp_v2 - icp_v1;
else
icp_2 = 65536 - icp_v1 + icp_v2;
if(!((icp_v2 >= icp_v1) && T2_ovf))
{
if(icp_2 == icp_1)
//if(1)
{
f = (11059200/icp_2)/12 * (unsigned long)max_icp;
dis_ok=1;
if(f>4000)
{
max_icp=16;
}
else
max_icp=1;
}
}//if(!((icp_v2 >= icp_v1) && T2_ovf))
else
max_icp=1;
icp_1=icp_2;
icp_ok=0;
begin=1;
}//if(icp_ok == 1)
} //void calc_F(void)
void f_to_dis(unsigned long f)
{
unsigned char i;
for(i=0;i<=5;i++)
{
new_Data = f%10;
f=f/10;
}
}
void main(void)
{
Init_Timer0();
Init_Timer2();
Relay=0;//Relay初始值
max_icp=1;
InitLcd();
DelayMs(15);
EA=1;/* interupt enable */
Timer_10ms=0;
while(1)
{
calc_F();
// f_to_dis(f);
if(Timer_10ms > 20)
{
if(dis_ok==1)
{
f_to_dis(f);
dis_ok=0;
}
if(begin==1)
{
icp_n = 0;
T2_ovf=0;
EXF2=0;
TF2=0;
begin=0;
Init_Timer2();
}
Timer_10ms=0;
}//if(Timer_1ms > 50)
EA=0;
LCD_Dis();
EA=1;
}//while(1)
}//main() 自己顶一下
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