#include<reg52.h>

sbit KEY1 = P3^1;    //定義調速按鍵
sbit PWM = P1^5;    //定義調速端口
unsigned char CYCLE;    //定義周期T=x*0.1ms
unsigned char PWM_ON ;    //定義高電平時間

void delay(unsigned int cnt)
{
        while(--cnt);
}

main()
{
        unsigned char PWM_Num;
        TMOD |=0x01;
        TH0=(65536-1000)/256;
        TL0=(65536-1000)%256;
        IE= 0x82;
        TR0=1;

        CYCLE = 10;
        while(1)
        {
                if(!KEY1)
                {
                        delay(10000);
                        if(!KEY1)
                        {
                                PWM_Num++;
                                if(PWM_Num==4)

                                        PWM_Num=0;
                                switch(PWM_Num)

                                {
                                        case 0:P0=0x06;PWM_ON=0;break;
                                        case 1:P0=0x5B;PWM_ON=4;break;
                                        case 2:P0=0x4F;PWM_ON=6;break;
                                        case 3:P0=0x66;PWM_ON=8;break;
                                        default:break;
                                }
                        }
                }
        }

}

void tim(void) interrupt 1 using 1
{
        static unsigned char count;
        TH0=(65536-1000)/256;
        TL0=(65536-1000)%256;

        if (count==PWM_ON)
        {
                PWM = 1;
        }
        count++;
        if(count == CYCLE)
        {
                count=0;
                if(PWM_ON!=0)
                        PWM = 0;

        }

}