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通过查询方式测量PWM波的正脉冲长

已有 658 次阅读2007-9-10 17:16 |系统分类:ARM| lpc2214, pwm, 测量

//LPC2214。通过查询p0.2管脚电平测量PWM的正脉冲长，通过查询发送串口

#include "config.h"

uint32 DUTY;

//延时
void DelayNS(uint32 dly)
{ uint32 i;
for(; dly>0; dly--)
for(i=0; i<5000; i++);
}

//用查询的方式测量
void PWM_Measure(void)
{
T0TC = 0x00;
while((IO0PIN&0x00000004) == 0); //检测p0.2的电压信号
T0TCR = 0x01;
while((IO0PIN&0x00000004) != 0);
T0TCR = 0x00;
if(T0TC <30000)
DUTY = T0TC;
}

//串口初始化
# define U0_BR 115200
void UART0_Init()
{ uint16 Div;
U0LCR = 0x83;
Div = (Fpclk >> 4) / U0_BR;
U0DLL = Div & 0XFF;
U0DLM = Div >> 8;
U0LCR = 0x03;
}

//串口发送
void SendBuf(uint8 *pdata)
{ uint8 i;
for (i=0; i<4; i++)
{ U0THR = *(pdata++);
while((U0LSR & 0x20) == 0); //判断THRE位是否为1?
}
}

int main(void)
{ uint8 data[4];
PINSEL0 = 0X00000005;    //设置i/o连接到UART0
IO0DIR = 0X00000000;
UART0_Init();
T0PR = 0;

while(1)
{
  PWM_Measure();
  data[0] = DUTY >> 24;
  data[1] = DUTY >> 16;
  data[2] = DUTY >> 8;
  data[3] = DUTY;

  SendBuf(data);
  DelayNS(10);
}
return(0);
}