WHILE LOOP PROBLEM FOR MICRO SECONDS WITH TIMER ??

[Ramazan Gülcan]

Posted on June 16, 2018 at 22:25

Hi friends,

The while loop does not work in the following function. Why could it be?

For STM32F407VG;

void US_BEKLE(uint16_t us)

{ uint16_t baslangic = (uint16_t)__HAL_TIM_GET_COUNTER(&htim1);

while(((uint16_t)__HAL_TIM_GET_COUNTER(&htim1)) - baslangic < us);

}

htim1.Instance = TIM1;

htim1.Init.Prescaler = 167; htim1.Init.CounterMode = TIM_COUNTERMODE_UP; htim1.Init.Period = 65000; htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1; htim1.Init.RepetitionCounter = 0;#microsecond-timer #while-loop

[Tesla DeLorean]

Posted on June 17, 2018 at 14:19

What compiler are you using?

unsigned numbers will not be negative.

uint16_t start, current;

uint16_t delta;

delta = (current - start); // will always be positive and represent accurately the number of cycles between the two points up to 65535 cycles.

If something like this doesn't work something is tragically wrong with the compiler.

uint16_t start = 

TIM1->CNT;

volatile uint16_t current;

do

{

  current = TIM1->CNT;

} while((current - start) < us);

[Ramazan Gülcan]

Posted on June 17, 2018 at 14:25

I use atollic.

I think I should not be negative.

But the problem is resolved in this way.

[Tesla DeLorean]

Posted on June 17, 2018 at 14:44

current-start = delta

0004-FFFC = 0008 ; wrap caseFFFB-FFFC = FFFF ; maximal case0008-0004 = 0004 ; nominal case

[Ramazan Gülcan]

Posted on June 17, 2018 at 15:35

I need to cast all of the subtraction in uint16_t format.

it also works as follows

while( (uint16_t) ((uint16_t)__HAL_TIM_GET_COUNTER(&htim1) - baslangic ) < us);