//LPC2214。利用cap0.0的捕获中断方式获取PWM的正脉冲长度，通过串口发送
#include "config.h"

uint32 DUTY=0x12345678;
uint8 flag=0;

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

//串口初始化
# define UART0_BR 115200
void UART0_Init(void)
{ uint16 Div;
 U0LCR = 0X83;
 Div = (Fpclk >> 4) / UART0_BR;
 U0DLL = Div;      //Fdiv % 256;
 U0DLM = Div>>8;      //Fdiv / 256;
 U0LCR = 0x03;
}

//定时器0初始化
void Timer0_Init(void)
{
 T0PR = 0;         //定时器0的时钟不分频
 T0CCR = 0x005;        //设置CAP1~4上升沿捕获并产生中断
 T0TC = 0;         //定时器0设置为0
 T0TCR = 1;
}

//中断函数，测量DUTY
void __irq Timer0_IRQ(void)
{
 uint32 time_0,time_1;
  if(flag==0)
  {
   time_0=T0CR0;       //记录CAP0.0上升沿捕获的时间
   flag=1;        //置标志位
   T0CCR=0x006;  //设置CAP0.0下降沿捕获并产生中断 
  }
   
  else
  { 
   time_1=T0CR0;       //记录CAP0.0下降沿捕获的时间
   flag=0;        //置标志位
   //获取DUTY值
   if((time_1-time_0)<30000)
   { DUTY = (time_1-time_0);
   }
   T0CCR=0x005;  //设置CAP0.0上升沿捕获并产生中断 
  }
 T0IR = 0x10;    //一定要清除中断标志位！
 VICVectAddr = 0;   //一定要有中断函数返回语句 
 }

//串口发送函数
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?
 }
}

//向量中断初始化
void VICVECT_Init(void)
{ VICIntSelect = 0x00000000;
 VICVectCntl0 = 0X20 | 4;    //使能cap0中断
 VICVectAddr0 = (uint32) Timer0_IRQ;
 VICIntEnable = 1<<4;
}

int main()
{ uint8 data[4];
 PINSEL0 = 0X00000025;    //设置p0.0,p0.1连接到UART0,p0.2连接到cap0.0
 
 UART0_Init();
 Timer0_Init();
 VICVECT_Init();
 
 while(1)
 { DelayNS(10);
  data[0] = DUTY >> 24;
  data[1] = DUTY >> 16;
  data[2] = DUTY >> 8;
  data[3] = DUTY;
  SendBuf( data );
 }
 return(0);
}