標(biāo)題: PWM范列—模擬的呼吸燈（有缺陷） [打印本頁]
作者: nius    時間: 2015-4-10 01:49
標(biāo)題: PWM范列—模擬的呼吸燈（有缺陷）
#include <reg52.h>
sbit PWMOUT = P0^0;
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
unsigned char HighRH = 0;
unsigned char HighRL = 0;
unsigned char LowRH = 0;
unsigned char LowRL = 0;
void ConfigPWM(unsigned int fr, unsigned char dc);
void ClosePWM();
void main()
{
    unsigned int i;
   
    EA = 1;     //開總中斷
    ENLED = 0;  //使能獨立LED
    ADDR3 = 1;
    ADDR2 = 1;
    ADDR1 = 1;
    ADDR0 = 0;
   
    while (1)
    {
static unsigned char Num1=0;
        ConfigPWM(100, Num1);    //頻率100Hz，占空比10%
        for (i=0; i<2000; i++);
        ClosePWM();
  Num1++;
  if(Num1==250)
   {
   Num1=0;
   }
    }
}
void ConfigPWM(unsigned int fr, unsigned char dc)
{
unsigned long tmp;
unsigned int high, low;
tmp = 11059200/12/fr;
high = (tmp*dc)/100;
low = tmp - high;
high = 65536 - high + 12;
low = 65536 - low + 12;
HighRH = (unsigned char)(high >>8);
HighRL = (unsigned char)high;
LowRH = (unsigned char)(low >> 8);
LowRL = (unsigned char)low;
TMOD &= 0xF0;
TMOD |= 0x01;
TH0 = HighRH;
TL0 = HighRL;
ET0 = 1;
TR0 = 1;
PWMOUT = 1;

}
void ClosePWM()
{
TR0 = 0;
ET0 = 0;
PWMOUT = 1;
}
void InterruptTimer0() interrupt 1
{
    if (PWMOUT == 1)  //當(dāng)前輸出為高電平時，裝載低電平值并輸出低電平
    {
        TH0 = LowRH;
        TL0 = LowRL;
        PWMOUT = 0;
    }
    else              //當(dāng)前輸出為低電平時，裝載高電平值并輸出高電平
    {
        TH0 = HighRH;
        TL0 = HighRL;
        PWMOUT = 1;
    }
}






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