unstable custom delay function (STM32 & STM32CubeIde)

[LadyMt]

Hello,

I have a small problem when using a custom delay function as follows :

void delay_us(uint32_t delayus) {

uint32_t start_count = __HAL_TIM_GET_COUNTER(&htim2);

while ((__HAL_TIM_GET_COUNTER(&htim2) - start_count) < delayus) {

 }
}

 The attached image shows the configuration of timer 2.

This delay function should allow me to generate short pulses. except that sometimes it does and sometimes nothing happens when I use it. I don't know what the problem is. Could you please help me?

[Radosław]

again  promotion to int

[LadyMt]

---

@AScha.3 wrote:

Did you start the timer , before using it ?

 HAL_TIM_Base_Start(&htim3);

---

yes I did

[Radosław]

Promotion to int and

while (((uint32_t)(__HAL_TIM_GET_COUNTER(&htim2) - start_count)) < delayus) {

 }

[AScha.3]

I just tried (on F303 , TIM3 ) : works, as it should do.

+

Did you set counter period (ARR) to something big ? 0xFFFF .

+ counter mode up ?

[Radosław]

while (((uint32_t)(__HAL_TIM_GET_COUNTER(&htim2) - start_count)) < delayus) {

 }

and ARR of timer must be 0xFFFFFFFF

[LadyMt]

---

@Radosław wrote:

Promotion to int and

while (((uint32_t)(__HAL_TIM_GET_COUNTER(&htim2) - start_count)) < delayus) {

 }

---

Even with this modification it still works randomly

[LadyMt]

---

@Radosław wrote:

while (((uint32_t)(__HAL_TIM_GET_COUNTER(&htim2) - start_count)) < delayus) {

 }

and ARR of timer must be 0xFFFFFFFF

---

yes timer ARR is 0xFFFFFFFF

[Radosław · Accepted solution]

Interrupt  can be a reason for longer delay, or hal funtion do something