51单片机模拟PWM输出占空比可调

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1、#include#defineUINTunsignedint#defineUCHARunsignedcharsbitpwm=P1^0;//pwm输出口sbitplus=P3^6;//按键调节增加输出脉宽sbitreduce=P3^7;//按键调节减小输出脉宽sbitduan=P2^6;//数码管的段选sbitwei=P2^7;//数码管的位选UCHARcodeSEG[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};UINTi;charj,k=5;voidtimer_init()//定时器0，8位自动重装{TMOD=0

2、x02;TH0=56;TL0=56;IE=0x82;TR0=1;}voiddelayms(UINTx)//延时{UINTi,j;for(i=x;i>0;i--)for(j=110;j>0;j--);}voidshow(inta)//数码管显示{intshi,ge;shi=a/10;ge=a%10;duan=1;P0=SEG[shi];duan=0;P0=0xff;wei=1;P0=0xfe;wei=0;delayms(3);duan=1;P0=SEG[ge];duan=0;P0=0xff;wei=1;P0=0xfd;wei=0;delayms(3);}voidtimer0()interrupt

3、1//定时器中断{i++;if(i==5000){i=0;j++;j=j%10;}if(j=10){k=10;}while(!plus);}}show(k);if(reduce==0){delayms(5);if(reduce==0){k--;if(k<=0){k=0;}while(!reduce);}}show(k);}voidmain(){timer_init();for(;;){adjust_pwm();}}