1. #include <reg51.h>
    3. #define uint unsigned int
    5. #define uchar unsigned char
    7. uchar time;
    9. double count = 26; //定义占空比，并初始占空比为26%
    11. sbit PWM = P2 ^ 0; //P2^0口输出PWM
    13. sbit key_add = P3 ^ 4; //电机加速的按键 的I/O口
    15. sbit key_dec = P3 ^ 5; //电机减速的按键 的I/O口
    17. /************函数声明**************/
    19. void delayxms(uint z); //延时
    21. void Motor_add(); //电机加速，即增加占空比
    23. void Motor_dec(); //电机减速，即减少占空比
    25. void timer0_init(); //定时器0初始化
    27. /*********主函数********************/
    29. void main()
    30. {
    31.     timer0_init();
    33.     delayxms(5);
    35.     while (1)
    36.     {
    37.         Motor_add();
    39.         Motor_dec();
    40.     }
    41. }
    43. /****************延时处理**********************/
    45. void delayxms(uint z) //延时xms程序
    46. {
    48.     uint x, y;
    50.     for (y = z; x > 0; x--)
    52.         for (y = 110; y > 0; y--);
    53. }
    55. void Motor_add() //电机加速
    56. {
    58.     if (key_add == 0)
    59.     {
    61.         delayxms(2); //此处时间不能太长，否者会的中断产生冲突
    63.         if (key_add == 0)
    64.         {
    65.             count += 0.5; //每按一次加速按键占空比加0.5
    67.             if (count >= 32) //限定占空比上限
    68.             {
    70.                 count = 32;
    71.             }
    72.         }
    74.         while (!key_add);
    75.     }
    76. }
    78. void Motor_dec() //电机减速
    79. {
    81.     if (key_dec == 0)
    82.     {
    84.         delayxms(2); //此处时间不能太长，否者会的中断产生冲突
    86.         if (key_dec == 0)
    87.         {
    89.             count -= 0.5; //每按一次减速按键占空比减0.5
    91.             if (count <= 25) //限定占空比下限
    92.             {
    94.                 count = 25;
    95.             }
    96.         }
    98.         while (!key_dec);
    99.     }
    100. }
    102. /***********定时器0初始化***********/
    104. void timer0_init()
    105. {
    107.     TMOD = 0x01; //定时器0工作于方式1
    109.     TH0 = (65536 - 10) / 256;
    111.     TL0 = (65536 - 10) % 256;
    113.     TR0 = 1;
    115.     ET0 = 1;
    117.     EA = 1;
    118. }
    120. /**************定时0中断处理******************/
    122. void timer0_int() interrupt 1
    123. {
    124.     TR0 = 0; //设置定时器初值期间，关闭定时器
    126.     TH0 = (65536 - 10) / 256;
    128.     TL0 = (65536 - 10) % 256;
    130.     TR0 = 1;
    132.     time++;
    134.     if (time < count) //count为占空比
    135.     {
    137.         PWM = 1; //输出高电平
    138.     }
    140.     else
    141.         PWM = 0;
    143.     if (time >= 100)
    144.     {
    145.         time = 0;
    146.     }
    147. }