Posted on June 27, 2017 at 13:33Hello
I am working on STM32F405. I need to detect falling/rising edge or high/low pulse using timer capture mode. Basically I am trying to interface an IR remote which works on RC5 protocol with STM32. But before that I just want to know how to detect high/low pulses. For this, I am using Timer8 Channel 3 which is on PC8. I have a connected gpio to this PC8 and toggling this GPIO with 500ms. I want to capture this pulse with 500ms high and 500ms low. Below is the code I am using :
/***** GPIO PIN *******/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
GPIO_InitTypeDef GPIO;
GPIO.GPIO_Pin = GPIO_Pin_10;
GPIO.GPIO_Speed = GPIO_Speed_100MHz;
GPIO.GPIO_Mode = GPIO_Mode_OUT;
GPIO.GPIO_OType = GPIO_OType_PP;
GPIO.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOD,&GPIO);
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource8, GPIO_AF_TIM8);
NVIC_InitStructure.NVIC_IRQChannel = TIM8_CC_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
TIM_ICInitTypeDef TIM_ICInitStructure;
TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_ICInit(TIM8, &TIM_ICInitStructure);
TIM_Cmd(TIM8, ENABLE);
TIM_ITConfig(TIM8, TIM_IT_CC2, ENABLE);
I have put the GPIO toggling code inside while(1) with the delay of 500ms.
Below is the interrupt
void TIM8_CC_IRQHandler(void)
{
if(TIM_GetITStatus(TIM8, TIM_IT_CC2) == SET)
{
//it enters in this if condition but failed to capture
int temp = TIM_GetCapture2(TIM8); //value of temp remains 0
}
}
What is wrong in the code.? Please help.
#timer #stm32-f #input-capture
