捕获测量频率问题？

只看该作者 · 2012-9-3 20:50

我用DIP-20封装的stc12c5410AD单片机的P3.7的捕获功能测量频率，通过串口返回到电脑，得到数据始终为零。求解答？

#include<stc12c5410AD.h>
#define uchar unsigned char
sbit LED = P1^7;
unsigned int rate_val = 0;
unsigned long count_1 = 0;
unsigned long count_2 = 0;
unsigned char flag = 0;
unsigned char ov_flag = 0;
unsigned char time_cnt = 0;
bit r_flag = 0;
void PCA_INIT(void)
{
  CMOD = 0x01; //  开PCA模块中断，设置空闲模式时关闭PCA计数阵列
  CCAPM0 = 0x11;  //  下降沿捕获使能
  CCON = 0x00; //  设置初始PCA计数阵列计数初值
  CH = 0; //
  CL = 0; // 设置初始PCA计数阵列计数初值
  CCAP0H = 0;  //
  CCAP0L = 0; //  清各标志位
  CR = 1;
  EPCA_LVD = 1;  // 开中断和低压检测中断位
}
void TIMER_INIT(void)
{
  TMOD = 0x21;
  SCON |= 0x50;
  TH0 = (65535 - 50000) / 256;
  TL0 = (65535 - 50000) % 256;
  TH1 = 0xfd;
  TL1 = 0xfd;
  ET0 = 1;
  TR0 = 1;
  TR1 = 1;
  //ES = 1;
  EA = 1;
}
void UART_send_byte(unsigned char  x)
{
  TI = 0;
  SBUF = x;
  while(TI == 0);
  TI = 0;
}
void UART_send_Nbyte(unsigned int  x)
{
  unsigned char array[2] = 0;
  unsigned char i = 0;
  array[0] = x >> 8;
  array[1] = x & 0xff;

  for(i = 0;i < 2; i++)
  {
UART_send_byte(array[i]);
  }
}
void main(void)
{
  PCA_INIT();
  TIMER_INIT();
  LED = 0;
  while(1)
  {
if(r_flag)
{
r_flag = 0;
LED = ~LED;
UART_send_Nbyte(rate_val);
TR0 = 1;
}
  }
}
void TIMER0(void) interrupt 1
{
  TH0 = (65535 - 50000) / 256;
  TL0 = (65535 - 50000) % 256;
  time_cnt ++;
  if(time_cnt == 2)
  {
time_cnt = 0;
r_flag = 1;
TR0 = 0;
  }
}
void PCA_ISR(void) interrupt 7 //PCA 中断服务函数
{
  if(CCF0)
  {
CCAP0H = CH;  //
CCAP0L = CL;
if(flag == 0)
{
count_1 = ov_flag * 65535 + CCAP0H * 256 + CCAP0L;
flag ++;
}
else
{
flag = 0;
count_2 = ov_flag * 65535 + CCAP0H * 256 + CCAP0L;
rate_val = 12000000 / 12 /(count_2 -count_1);
CH = 0;
   CL = 0;
   CCAP0H = 0;
   CCAP0L = 0;
ov_flag = 0;
}
CCF0 = 0;
  }
  if(CF)
  {
CF = 0;
ov_flag ++;
  }
}