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):
- // Hold onto the Channel 1 init structure -- we will use it to reverse
- // polarity on every edge interrupt.
- static TIM_ICInitTypeDef TIM_CH1_ICInitStructure;
- #define GPIO_AF_TIM2 GPIO_AF_2
- void ConfigPwmIn() {
- GPIO_InitTypeDef GPIO_InitStructure;
- TIM_ICInitTypeDef TIM_ICInitStructure;
- NVIC_InitTypeDef NVIC_InitStructure;
- TIM_DeInit(TIM2 );
- /* TIM2 clock enable */
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);
- /* GPIOC clock enable */
- RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOD,ENABLE);
- /* TIM2 GPIO pin configuration : CH1=PD3,C2=PD4,CH3=PD7,CH4=PD6 */
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_4 | GPIO_Pin_7 | GPIO_Pin_6;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
- GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
- GPIO_Init(GPIOD,&GPIO_InitStructure);
- /* Connect pins to TIM3 AF2 */
- GPIO_PinAFConfig(GPIOD,GPIO_PinSource3,GPIO_AF_TIM2 );
- GPIO_PinAFConfig(GPIOD,GPIO_PinSource4,GPIO_PinSource7,GPIO_PinSource6,GPIO_AF_TIM2 );
- NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
- NVIC_Init(&NVIC_InitStructure);
- /* Enable capture*/
- TIM_CH1_ICInitStructure.TIM_Channel = TIM_Channel_1;
- TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
- TIM_CH1_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
- TIM_CH1_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
- TIM_CH1_ICInitStructure.TIM_ICFilter = 0;
- TIM_ICInit(TIM2,&TIM_ICInitStructure);
- TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
- TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
- TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
- TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
- TIM_ICInitStructure.TIM_ICFilter = 0;
- TIM_ICInit(TIM2,&TIM_ICInitStructure);
- TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;
- TIM_ICInit(TIM2,&TIM_ICInitStructure);
- TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;
- TIM_ICInit(TIM2,&TIM_ICInitStructure);
- /* Enable TIM2 */
- TIM_Cmd(TIM2,ENABLE);
- /* Enable CC1-4 interrupt */
- TIM_ITConfig(TIM2,TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4,ENABLE);
- /* Clear CC1 Flag*/
- TIM_ClearFlag(TIM2,TIM_FLAG_CC1 | TIM_FLAG_CC2 | TIM_FLAG_CC3 | TIM_FLAG_CC4 );
- }
- static volatile uint32_t ccr[4];
- static volatile char pulseState = 0;
- void TIM2_IRQHandler() {
- if (TIM2 ->SR & TIM_IT_CC1 ) {
- TIM2 ->SR &= (~TIM_IT_CC1 );
- if (pulseState == 0) {
- TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
- // Any time we get a rising edge on CH1,we reset the counter. All channels are
- // phase aligned,so they all use this as a reference.
- TIM_SetCounter(TIM2,0);
- } else {
- TIM_CH1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
- // Pull the value on the falling edge.
- ccr[0] = TIM_GetCapture1(TIM2 );
- }
- pulseState = !pulseState;
- // Reverse polarity.
- TIM_ICInit(TIM2,&TIM_CH1_ICInitStructure);
- }
- if (TIM2 ->SR & TIM_IT_CC2 ) {
- TIM2 ->SR &= (~TIM_IT_CC2 );
- ccr[1] = TIM_GetCapture2(TIM2 );
- }
- if (TIM2 ->SR & TIM_IT_CC3 ) {
- TIM2 ->SR &= (~TIM_IT_CC3 );
- ccr[2] = TIM_GetCapture3(TIM2 );
- }
- if (TIM2 ->SR & TIM_IT_CC4 ) {
- TIM2 ->SR &= (~TIM_IT_CC4 );
- ccr[3] = TIM_GetCapture4(TIM2 );
- }
- }
