How to give delay when working gpio toggel?

[LACTIC]

Hello ,

I am using Standard Peripheral Library with STM32F3VCT6 mcu. I want give delay without using timer of it means want give delay by using RCC clock. Is there any thing by which it can be happen.

[berendi]

RCC won't help you at counting elapsed clock cycles. There are a plenty of different timers on the STM32F3 series, depending on the exact model.

Basic timers, general purpose timers, advanced timer, a high-resolution timer, SysTick timer, DWT cycle counter, or the RTC for longer intervals. Pick one.

[Nikita91]

If you want a delay of few microseconds you can use the cycle couter. Example:

bspTsMhzDiv is the MCU sysclk frequeny in MHz (168 if the sysclk is 168MHz)

#pragma GCC push_options
#pragma GCC optimize ("O3")
 
void bspDelayUs (uint32_t us)
{
	volatile uint32_t cycles = (bspTsMhzDiv * us) - 10 ;	// Remove some cycles for instructions
	volatile uint32_t start = DWT->CYCCNT ;
 
	do
	{
	} while ((DWT->CYCCNT - start) < cycles) ;
}
 
#pragma GCC pop_options
 

[Piranha]

The cycles and start variables doesn't need to be volatile, which can potentially limit some optimization. And what's the point of using do-while in place where simple while does the same? :)

[berendi]

When implementing a delay loop, you don't want certain optimizations to take place.