单片机PWM程序是怎么编写的啊，能给一个简单的例子吗？

有PWM功能的单片机入STC12系列单片机，直接给专用寄存器赋值开启相应定时器就可以了。普通单单片机，PWM需要用自己来调配。比如：

#include<reg51.h>

unsigned char pwhh,pwhl,pwlh,pwll

bit flag

sbit pwm=P1^0

void t0isr() interrupt 1

{

if(flag)

{

TH0=pwhh

TL0=pwhl

}

else

{

TH0=pwlh

TL0=pwll

}

pwm=~pwm

}

main()

{

TMOD=0x01

pwhh=(65536-1000)/256

pwhl=(65536-1000)%256

pwlh=(65536-500)/256

pwll=(65536-500)%256

TH0=pwhh

L0=pwhl

TR0=1

ET0=1

EA=1

while(1)

}

#include<reg51.h>

#define uchar unsigned char

uchar pwm=50,cnt

sbit pluse=P1^0

sbit keyu=P1^4

sbit keyd=P1^5

void t0isr() interrupt 1

{

TH0=(65536-100)/256

TL0=(65536-100)%256

cnt++

if(pwm>0)

{

if(cnt>100)cnt=0

if(cnt<=pwm)pluse=1

else pluse=0

}

else pluse=0

}

main()

{

TMOD=0x01

TH0=(65536-100)/256

TL0=(65536-100)%256

TR0=1

ET0=1

EA=1

while(1)

{

if(keyu==0)

{

while(keyu==0)

pwm++

if(pwm>100)pwm=100

}

if(keyd==0)

{

while(keyd==0)

if(pwm>0)pwm--

}

}

}

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