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工作原理见书《51单片机应用及原理——基于KeilC和Proteus，陈海宴》P178-180
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步进电机控制应用实例
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设计要求：
- 采用定时中断方式控制步进机的转速，定时单位时长为10ms。
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速度设置在 1/2/3/4 四个档位， 1 档最快，依次递减，能够控制步进电机的停、转和方向，同时显示步进机的当前档位。
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设计思路：
- 通过P1控制步进电机的转动，P1.0->a，P1.1->b，P1.2->c，P1.3->d，ULN2003A作为步进电机驱动
- P2.0-P2.3对应数码管显示（使用7447芯片对应将BCD码转换成7端LED数码管），通过7447简单驱动数码管（P2只需要发送1/2/3/4即可）
- 通过定时器计数，到达设定值时步进电机转动1/4圈，计数清零
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元件清单：
- AT89C51
- BUTTON
- MOTOR-STEPPER
- RESPACK-8
- 7SEG-COM-ANODE
- ULN2003A
- 7447
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实现代码：
1 #include2 typedef unsigned char uchar; 3 uchar direction = 0; //0为正转,1为反转 4 uchar onoff = 0; //关为0,开为1 5 uchar n = 0; //每次定时器中断触发时n++,当n==max时电机转动1/4 6 uchar max = 10; 7 uchar index = 0; //通过index指示电机转动,AB,BC,CD,DA 8 sbit LED = P3 ^ 7; //当n==max时LED闪烁提示 9 int main() 10 { 11 /* LED */ 12 P2 = 0xff; 13 /* 初始化中断 */ 14 EA = 1; 15 EX0 = 1; //要用到的中断是两个外部中断和定时器中断0 16 IT0 = 1; 17 EX1 = 1; 18 IT1 = 1; 19 ET0 = 1; 20 /* 定时器0 */ 21 TMOD = 0x01; //使用定时器0,方式1 22 TH0 = (65536 - 10000) / 256; //12MHz晶振下,定时器为10ms触发中断,更方便观察转动情况 23 TL0 = (65536 - 10000) % 256; 24 TR0 = 1; 25 while(1) 26 { 27 switch(P0) 28 { 29 case 0xfe: //11111110 30 max = 1; 31 P2 = 1; 32 break; 33 case 0xfd: //11111101 34 max = 10; 35 P2 = 2; 36 break; 37 case 0xfb: //11111011 38 max = 50; 39 P2 = 3; 40 break; 41 case 0xf7: //11110111 42 max = 100; 43 P2 = 4; 44 break; 45 } 46 } 47 } 48 void Stop()interrupt 0 49 { 50 onoff++; 51 if (onoff > 1) 52 onoff = 0; 53 } 54 void int1()interrupt 2 55 { 56 direction++; 57 if (direction > 1) 58 direction = 0; 59 } 60 void delay50ms(void) 61 { 62 unsigned char a, b; 63 for(b = 173; b > 0; b--) 64 for(a = 143; a > 0; a--); 65 } 66 void time()interrupt 1 67 { 68 TH0 = (65536 - 10000) / 256; 69 TL0 = (65536 - 10000) % 256; 70 if (onoff == 1) //在开状态下 71 { 72 if (n == max) //设定档位速度,经过了max次中断后,步进电机转1/4圈 73 { 74 LED = 0; //每次n==max时LED闪烁 75 delay50ms(); 76 LED = 1; 77 if (direction == 0) 78 { 79 switch(index) //正转时以AB,BC,CD,DA顺序 80 { 81 case 0:P1 = 0x03;break; //00000011 AB高电平 82 case 1:P1 = 0x06;break; //00000110 BC高电平 83 case 2:P1 = 0x0c;break; //00001100 CD高电平 84 case 3:P1 = 0x09;break; //00001001 DA高电平 85 } 86 index ++; 87 if (index == 4) //步进电机转完一圈时index清零 88 index = 0; 89 n = 0; //到达max,n重置为0 90 } 91 if (direction == 1) 92 { 93 switch(index) //反转时以DA,CD,BC,AB顺序 94 { 95 case 0:P1 = 0x09;break; 96 case 1:P1 = 0x0c;break; 97 case 2:P1 = 0x06;break; 98 case 3:P1 = 0x03;break; 99 } 100 index ++; 101 if (index == 4) 102 index = 0; 103 n = 0; 104 } 105 else n = 0; 106 } 107 n++; //n!=max时,n++ 108 } 109 else n = 0; //在关状态下,n始终为0,无法触发电机转动 110 }