Question
Can't read CCR1 value stm32f3
Posted on August 09, 2017 at 15:48
Hello guys,
So I'mdoing simple timer capture inputpractice exercise. I have HC-SR 04 sensor and want to drive it with stm32f3 discovery board. If someone could check what is wrong with my code:
#include 'stm32f303xc.h'
long cnt1 = 0;
long cnt2 = 0;
short x = 0;
void Delay(uint32_t circles);
int main(void){
RCC->AHBENR = RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOEEN; //clock for A and E ports
RCC->APB1ENR = RCC_APB1ENR_TIM3EN; //clock for timer
GPIOE->MODER |= GPIO_MODER_MODER11_0 // Green
| GPIO_MODER_MODER10_0 // Orange
| GPIO_MODER_MODER9_0 // Red LED output mode
| GPIO_MODER_MODER2_0; // PE02 - TRIGG PIN outputmode
TIM3->CCMR1 = TIM_CCMR1_CC1S_0; //CC AS INPUT, MAP TI1 (PE03)
TIM3->CCER = TIM_CCER_CC1NP_Msk | TIM_CCER_CC1P_Msk; // EVENT ON RISING AND FALLING EDGE
TIM3->CCMR1 = TIM_CCMR1_IC1PSC; // NO PSC - CAPTURE EACH EVENT
TIM3->CCER = TIM_CCER_CC1E; // ENABLE INPUT CAPTURE COMPARE MODE
TIM3->DIER = TIM_DIER_CC1IE; // ENABLE CC INTERRUPT
TIM3->CR1 = TIM_CR1_CEN; // ENABLE TIM3
NVIC_EnableIRQ(TIM3_IRQn); // ENABLE NVIC INTERRUPT FOR TIM3
Delay(800000); // Wait some time
GPIOE->ODR |= GPIO_ODR_2; // Set PE02
Delay(8000); // Wait 10us
GPIOE->ODR &= ~(GPIO_ODR_2); // Reset PE02
while(1){}
}
void TIM3_IRQHandler(void)
{
if(x==0)
{
cnt1 = TIM3->CCR1; // GET VALUE
x++; // REMEMBER THAT NEXT IS FALLING EDGE
GPIOE->ODR |= GPIO_ODR_10; // SET LED TO CONFIRM
}
else if(x==1)
{
cnt2 = TIM3->CCR1; // GET VALUE
x--; // NEXT IS RISING EDGE
GPIOE->ODR |= GPIO_ODR_11; // SET LED TO CONFIRM
}
}
// SysTick clock = 8MHz so you get 1sec delay afret 8000000 circles
//
void Delay(uint32_t circles)
{
SysTick->LOAD = circles - 1;
SysTick->CTRL |= SysTick_CTRL_CLKSOURCE_Msk |
SysTick_CTRL_ENABLE_Msk;
while(!(SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk));
SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
}
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#discovery #stm32 #input-capture #timer-interrupt