在使用带霍尔编码器的电机时，需要捕获脉冲，来达到测电机的转速的目的，捕获脉冲的方式有很多，我刚开始选用的是定时器捕获，后因需要测度多个电机的速度，STM32F103的定时器感觉不够用，所以选择EXTI以达到捕获高电平的目的，再用TIM定时器中断计时。


5 F3 T$ J, U8 @* ]1 y+ \% a以下为EXTI配置
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1. <font face="微软雅黑" size="3">/* Data defien ---------------------------------------------------------------------------------------*/
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2. uint16_t motor_1_At = 0;        //电机A相的脉冲数
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3. uint16_t motor_1_Bt = 0;   //电机B相的脉冲数
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4. uint16_t speed_motor_1;         //电机的转速
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5. 
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6. /***
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7.   * @name speed_measure()
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8.   * @brief
   
9.   * @param NONE
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10.   * @retval NONE
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11.   */
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12. void speed_measure_extix(void)
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13. {
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14.     EXTI_InitTypeDef EXTI_InitStructure;
    
15.     NVIC_InitTypeDef NVIC_InitStructure;
    
16.     GPIO_InitTypeDef GPIO_InitStructure;
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17.    
    
18.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOG|RCC_APB2Periph_GPIOD, ENABLE);     //使能PORTA,PORTE时钟
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19.    
    
20.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
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21.    
    
22.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;                  //motor_1_A-->PG9
    
23.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD;
    
24.     GPIO_Init(GPIOG, &GPIO_InitStructure);
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25.    
    
26.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;                  //motor_1_B-->PD8
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27.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD;
    
28.     GPIO_Init(GPIOD, &GPIO_InitStructure);
    
29.    
    
30.    
    
31.    
    
32.    
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33.     GPIO_EXTILineConfig(GPIO_PortSourceGPIOG,GPIO_PinSource9);
    
34.     EXTI_InitStructure.EXTI_Line = EXTI_Line9;
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35.     EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
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36.     EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
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37.     EXTI_InitStructure.EXTI_LineCmd = ENABLE;
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38.     EXTI_Init(&EXTI_InitStructure);
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39.    
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40.     GPIO_EXTILineConfig(GPIO_PortSourceGPIOD,GPIO_PinSource8);
    
41.     EXTI_InitStructure.EXTI_Line = EXTI_Line8;
    
42.     EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
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43.     EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
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44.     EXTI_InitStructure.EXTI_LineCmd = ENABLE;
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45.     EXTI_Init(&EXTI_InitStructure);
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46.    
    
47.     NVIC_InitStructure.NVIC_IRQChannel = EXTI9_5_IRQn;
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48.     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;
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49.     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0X00;
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50.     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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51.     NVIC_Init(&NVIC_InitStructure);   
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52. }
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53. 
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54. void EXTI9_5_IRQHandler(void)
    
55. {
    
56.     if(EXTI_GetITStatus(EXTI_Line8)!=RESET)//判断某个线上的中断是否发生
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57.     {   
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58.     motor_1_Bt++;
    
59.     EXTI_ClearITPendingBit(EXTI_Line8);
    
60.     }
    
61.     if(EXTI_GetITStatus(EXTI_Line9)!=RESET)//判断某个线上的中断是否发生
    
62.     {   
    
63.     motor_1_At++;
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64.     EXTI_ClearITPendingBit(EXTI_Line9);
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65.     }
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66.    
    
67. }
    
68. </font>

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因为unsigned char类型整数表示的范围为： 0~2^8-1，所以需要用定时器进行置0，以下为代码：
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1. <font face="微软雅黑" size="3">/***
   
2.   * @name speed_measure_time()
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3.   * @brief  TIM2
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4.   * @param NONE
   
5.   * @retval NONE
   
6.   */
   
7. void speed_measure_time(u16 arr, u16 psc)
   
8. {
   
9.     TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
   
10.     NVIC_InitTypeDef NVIC_InitStructure;
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11.     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
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12.    
    
13.     TIM_TimeBaseStructure.TIM_Period = arr;
    
14.     TIM_TimeBaseStructure.TIM_Prescaler = psc;
    
15.     TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    
16.     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    
17.     TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
    
18.     TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
    
19.    
    
20.     NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    
21.     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
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22.     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
    
23.     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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24.     NVIC_Init(&NVIC_InitStructure);
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25.    
    
26.     TIM_Cmd(TIM2, ENABLE);
    
27.    
    
28. }
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29. 
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30. void TIM2_IRQHandler(void)
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31. {
    
32.     if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
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33.     {
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34.         TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
    
35.         speed_motor_1 = (motor_1_At + motor_1_Bt);
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36.         motor_1_At = 0;
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37.         motor_1_Bt = 0;
    
38.         
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39.     }
    
40. }
    
41. </font>

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代码中的speed_motor_1为设置时间内的电机A相与B相的脉冲数之和。

定时器时间的设置可以通过（u16 arr, u16 psc）实现，附上计算公式

T =[ (arr+1) + (psc+1)]/72000000

使用时直接调用这两个函数：

1. <font face="微软雅黑" size="3">void speed_measure_extix(void) ；
   
2. void speed_measure_time(u16 arr, u16 psc)；</font>

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