转一个stm32单一计时器多路捕获PWM信号的方案

地址：http://bbs.5imx3g.com/forum.php?mod=viewthread&tid=70

OP: Ok, I've got it (mostly) worked out thanks to a post here and a post elsewhere. The key is changing polarity of the signal in the IRQ handler. Here, I am assuming that the PWMs are phase aligned, so I only need to check for rising/falling edges of the Channel 1 signal. But this could easily be adapted to allow for PWMs that are not phase-aligned.
Here is my current code, reading 4 PWM signals with a single timer (the ccr[] array holds the current PWM pulse widths):

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;
5. #define GPIO_AF_TIM2 GPIO_AF_2
7. void ConfigPwmIn() {
8. GPIO_InitTypeDef GPIO_InitStructure;
9. TIM_ICInitTypeDef TIM_ICInitStructure;
10. NVIC_InitTypeDef NVIC_InitStructure;
12. TIM_DeInit(TIM2 );
14. /* TIM2 clock enable */
15. RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
17. /* GPIOC clock enable */
18. RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOD, ENABLE);
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);
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 );
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);
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);
58. /* Enable TIM2 */
59. TIM_Cmd(TIM2, ENABLE);
61. /* Enable CC1-4 interrupt */
62. TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);
64. /* Clear CC1 Flag*/
65. TIM_ClearFlag(TIM2, TIM_FLAG_CC1 | TIM_FLAG_CC2 | TIM_FLAG_CC3 | TIM_FLAG_CC4 );
66. }
68. static volatile uint32_t ccr[4];
69. static volatile char pulseState = 0;
71. void TIM2_IRQHandler() {
72. if (TIM2 ->SR & TIM_IT_CC1 ) {
73.   TIM2 ->SR &= (~TIM_IT_CC1 );
75.   if (pulseState == 0) {
76.    TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
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;
84.    // Pull the value on the falling edge.
85.    ccr[0] = TIM_GetCapture1(TIM2 );
86.   }
87.   pulseState = !pulseState;
89.   // Reverse polarity.
90.   TIM_ICInit(TIM2, &TIM_CH1_ICInitStructure);
91. }
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. }

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