I'm using an STM32F401CCU6 microcontroller and am trying to generate a timer interrupt of 10 us with TIMER3.The timer is a update event timer. The formula I'm using is:
Update_event = TIx_CLK/((PSC + 1)*(ARR + 1))
Below, I've given my clock configuration. Secondly, I got my ARR = (840-1) and the Prescaler = (1-1) for a 10 µs timer. Is this incorrect?
Also, I'm using the Keil development software and when I run the code,my first query is the right psc and arr values . Secondly when ever interrupt is generated my timer values is different each time interrupt is generated , the counts are drifting ??.My Code :
void TIM3_Init(void)
{
__HAL_RCC_TIM3_CLK_ENABLE();
TIM3->SR &=~(TIM_CR1_CEN);
TIM3->CNT = 0 ;
TIM3->ARR = (839);
TIM3->PSC = (1-1) ;
TIM3->DIER |=TIM_DIER_UIE;
HAL_NVIC_SetPriority(TIM3_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(TIM3_IRQn);
TIM3->CR1 |= TIM_CR1_CEN ; // First BreakPoint
}TIM3Interrupt routine :
void TIM3_IRQHandler(void)
{
HAL_TIM_IRQHandler(&htim3); // Second Breakpoint
}How I debug is by first placing breakpoint on my TIM3_Init function last line , Hit that breakpoint , Reset my Timer on the Keil IDE as t1 , and run until TIM3 Interrupt is generated and note the value , as I said , the values are drifting , first they are 14us , then .5us , I dont understand how difficult could it be to Initialize a timer , I've done it with stm32f103 series and never had a headache . Please tell me what Im doing wrong , could my RCC Clock be the problem which I doubt , or IDE settings. I've been fighting with this simple initialization for 3 days .
