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?

[AScha.3]

Hi,

you should not use some HAL lib calls , if you expect "us" timing, HAL might need 1 us itself .

And why on 32 bit counter ? need more than 60ms delay ? then use HAL_delay () .

I would try : (on TIM3)

void delay_us(uint32_t delayus) 
{
  TIM3->CNT = 0x0000 ; // start_count 
  while ((TIM3->CNT) < delayus) { };
}

[Radosław]

Default promotion to  INT.

[LadyMt]

the 32 bit counter was in the tutorial I followed on youtube.

why timer 3 and not timer 2?

[LadyMt]

I'm starting out in stm32 and unfortunately I don't understand what you're trying to point out. Could you be clearer? Please.

[Andrew Neil]

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@LadyMt wrote:

 the tutorial I followed on youtube.

---

Please give a link to that tutorial

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@LadyMt wrote:

sometimes it does and sometimes nothing happens when I use it. 

---

What do you mean by, "nothing happens"?

• There is no delay?
• Your system hangs?
• other ... ?

[LadyMt]

If I try what you suggest, I get stuck in the while loop.

Would you know why?

[Radosław]

AGAIN  propotion to int

Test your conditions

[LadyMt]

---

@Andrew Neil wrote:

---

@LadyMt wrote:

 the tutorial I followed on youtube.

---

Please give a link to that tutorial

---

I can't find the video exactly. But I can show you another similar video that I also watched. : How to create delay in nano/micro seconds using timers in stm32 (youtube.com)

---

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@LadyMt wrote:

sometimes it does and sometimes nothing happens when I use it. 

---

What do you mean by, "nothing happens"?

• There is no delay?
• Your system hangs?
• other ... ?

---

What I mean by "nothing happens" is that there are no delays.
I check this on an oscilloscope.

[AScha.3]

Did you start the timer , before using it ?

 HAL_TIM_Base_Start(&htim3);