Tạo xung tăng giảm độ rộng khi nhấn nút

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// Write by Huu Quang

#include <REGX52.H>

#define tan_so 20

char millisec;

char do_rong_xung;

void delay_ms(unsigned int timer)

{

  int i,j;

for(i=0;i<timer;i++)

for(j=0;j<121;j++);

}

/*

void ISR_1000ms(void) interrupt 1 // ham ngat timer 0

{

TF0 = 0;//xoa co tran

TH0 =0xE2; // nap du lieu vao thanh ghi timer

TL0 =0x0A;

TR0=1;

    P2_1=~P2_1;

}

*/

int main()

{

 

TMOD=0x01;//timer 0 che do 16 bit

TR0=1;    //cho phep timer 0 hoat dong

TH0=(0xFFFF-50000)>>8;

TL0=(0xFFFF-50000)|0xFF;

while(1)

{

while(TF0!=0) 

{

millisec++;

TF0=0;

TH0 =(0xFFFF-50000)>>8; // nap du lieu vao thanh ghi timer

TL0 =(0xFFFF-50000);

if(millisec<=do_rong_xung)

{

P2_0=1;

}

else if(millisec<=tan_so)

{

P2_0=0;

}

else millisec=0;

}

if(P2_1==0)

{

while(P2_2==0);

delay_ms(100);

do_rong_xung+=1;

if(do_rong_xung>=tan_so)

do_rong_xung=1;

}

}

}