无刷云台研究记录——遥控：PWM脉冲宽度测量

Tristan.Wu

无刷云台研究记录——遥控：PWM脉冲宽度测量 [复制链接]

在了解遥控数据交换协议之前，首先对常用的协议有所了解，推荐一篇科普文章：
http://www.docin.com/p-680140417.html
若该链接无效可以搜索关键字“APM PX4飞控开发笔记-第五章:PWM、PPM与S.bus”

之后选择自己需要的协议进行设计，我用的是PWM，所以需要通过定时器对脉冲宽度进行读取。具体代码如下，这并不是我写的，但经测试，可以使用。

1. // Hold onto the Channel 1 init structure -- we will use it to reverse  
   
2. // polarity on every edge interrupt.  
   
3. static TIM_ICInitTypeDef TIM_CH1_ICInitStructure;  
   
4.   
   
5. #define GPIO_AF_TIM2 GPIO_AF_2  
   
6.   
   
7. void ConfigPwmIn() {  
   
8. GPIO_InitTypeDef GPIO_InitStructure;  
   
9. TIM_ICInitTypeDef TIM_ICInitStructure;  
   
10. NVIC_InitTypeDef NVIC_InitStructure;  
    
11.   
    
12. TIM_DeInit(TIM2 );  
    
13.   
    
14. /* TIM2 clock enable */  
    
15. RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);  
    
16.   
    
17. /* GPIOC clock enable */  
    
18. RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOD, ENABLE);  
    
19.   
    
20. /* TIM2 GPIO pin configuration : CH1=PD3, C2=PD4, CH3=PD7, CH4=PD6 */  
    
21. GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_4 | GPIO_Pin_7 | GPIO_Pin_6;  
    
22. GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;  
    
23. GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;  
    
24. GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;  
    
25. GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;  
    
26. GPIO_Init(GPIOD, &GPIO_InitStructure);  
    
27.   
    
28. /* Connect pins to TIM3 AF2 */  
    
29. GPIO_PinAFConfig(GPIOD, GPIO_PinSource3, GPIO_AF_TIM2 );  
    
30. GPIO_PinAFConfig(GPIOD, GPIO_PinSource4, GPIO_AF_TIM2 );  
    
31. GPIO_PinAFConfig(GPIOD, GPIO_PinSource7, GPIO_AF_TIM2 );  
    
32. GPIO_PinAFConfig(GPIOD, GPIO_PinSource6, GPIO_AF_TIM2 );  
    
33.   
    
34. NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;  
    
35. NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;  
    
36. NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;  
    
37. NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;  
    
38. NVIC_Init(&NVIC_InitStructure);  
    
39.   
    
40. /* Enable capture*/  
    
41. TIM_CH1_ICInitStructure.TIM_Channel = TIM_Channel_1;  
    
42. TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;  
    
43. TIM_CH1_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;  
    
44. TIM_CH1_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;  
    
45. TIM_CH1_ICInitStructure.TIM_ICFilter = 0;  
    
46. TIM_ICInit(TIM2, &TIM_ICInitStructure);  
    
47. TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;  
    
48. TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;  
    
49. TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;  
    
50. TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;  
    
51. TIM_ICInitStructure.TIM_ICFilter = 0;  
    
52. TIM_ICInit(TIM2, &TIM_ICInitStructure);  
    
53. TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;  
    
54. TIM_ICInit(TIM2, &TIM_ICInitStructure);  
    
55. TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;  
    
56. TIM_ICInit(TIM2, &TIM_ICInitStructure);  
    
57.   
    
58. /* Enable TIM2 */  
    
59. TIM_Cmd(TIM2, ENABLE);  
    
60.   
    
61. /* Enable CC1-4 interrupt */  
    
62. TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);  
    
63.   
    
64. /* Clear CC1 Flag*/  
    
65. TIM_ClearFlag(TIM2, TIM_FLAG_CC1 | TIM_FLAG_CC2 | TIM_FLAG_CC3 | TIM_FLAG_CC4 );  
    
66. }  
    
67.   
    
68. static volatile uint32_t ccr[4];  
    
69. static volatile char pulseState = 0;  
    
70.   
    
71. void TIM2_IRQHandler() {  
    
72. if (TIM2 ->SR & TIM_IT_CC1 ) {  
    
73.   TIM2 ->SR &= (~TIM_IT_CC1 );  
    
74.   
    
75.   if (pulseState == 0) {  
    
76.    TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;  
    
77.   
    
78.    // Any time we get a rising edge on CH1, we reset the counter. All channels are  
    
79.    // phase aligned, so they all use this as a reference.  
    
80.    TIM_SetCounter(TIM2, 0);  
    
81.   } else {  
    
82.    TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;  
    
83.   
    
84.    // Pull the value on the falling edge.  
    
85.    ccr[0] = TIM_GetCapture1(TIM2 );  
    
86.   }  
    
87.   pulseState = !pulseState;  
    
88.   
    
89.   // Reverse polarity.  
    
90.   TIM_ICInit(TIM2, &TIM_CH1_ICInitStructure);  
    
91. }  
    
92.   
    
93. if (TIM2 ->SR & TIM_IT_CC2 ) {  
    
94.   TIM2 ->SR &= (~TIM_IT_CC2 );  
    
95.   ccr[1] = TIM_GetCapture2(TIM2 );  
    
96. }  
    
97. if (TIM2 ->SR & TIM_IT_CC3 ) {  
    
98.   TIM2 ->SR &= (~TIM_IT_CC3 );  
    
99.   ccr[2] = TIM_GetCapture3(TIM2 );  
    
100. }  
     
101. if (TIM2 ->SR & TIM_IT_CC4 ) {  
     
102.   TIM2 ->SR &= (~TIM_IT_CC4 );  
     
103.   ccr[3] = TIM_GetCapture4(TIM2 );  
     
104. }  
     
105. }

复制代码

以上代码来自《stm32 pwm捕获学习笔记》，该Blog中列出了几种测量方式，可以根据需要选择合适的加以运用。

获取了PWM脉冲宽度，就可以归一化处理后加入控制。

绿茶

不错  看看 ：）