small and fast: µs-delay with TIMER4

[timbo2023]

First suggestion after internet inquiry:

// Initialization procedure:

RCC->APB1ENR = 0b00000000000000000000000000000010;

TIM4->PSC = 15; 
TIM4->ARR = 65534;
TIM4->CR1 = (1<<0);

// Function:

void delay_US(uint32_t us)
{
uint32_t i;
for( i = 0; i <= us; i++ )
{
/* Clear the count */
TIM4->CNT = 0;
/* Wait UIF to be set */
while((TIM4->SR & TIM_SR_UIF) == 0); /* ?!?!? */
/* Reset UIF */
TIM4->SR &= ~TIM_SR_UIF;
}
}

I need a short common µs-delay - any ideas for the marked µc?

[Andrew Neil]

Why would you want a delay to be Fast ?

Surely, a delay is a deliberate waste of time.

A microsecond is a microsecond - it can't be "slow" or "fast" ?

Did you mean, accurate ?

[timbo2023]

correction accepted - accurate to ~20ns ...

Is there a possibility with DWT (Data Watchpoint Trigger) ?

Could you explain it shortly?