Using SysTick Timer as normal timer

[pa]

Posted on July 26, 2013 at 10:58

Hi all

I've a question: How does I have to configure the systick timer to operate without interrupts and so I can check the count value... I've tried this, but if I check if SysTick-VAL < 480 or < 48000 is the same. The pin toggels with ~360ns

int
main(
void
) 

{ 

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE); 

GPIO_InitTypeDef GPIO_InitStructure; 


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; 

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; 

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; 

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; 

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; 

GPIO_Init(GPIOB, &GPIO_InitStructure); 


SysTick->LOAD = 0xFFFFFF; 
/// -> Max 

SysTick->VAL = 0; 

SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk; 
/// Enable timer 


while
(1){ 

SysTick->VAL = 0; 

while
(SysTick->VAL < 48000); 

GPIOB->ODR ^= GPIO_Pin_2; 

} 

return
0; 

}

Best regards P51D

[waclawek.jan]

Posted on July 29, 2013 at 18:50

PM0214, ch.4.5:

The processor has a 24-bit system timer, SysTick, that counts down from the reload value to zero, reloads (wraps to) the value in the STK_LOAD register on the next clock edge, then counts down on subsequent clocks. JW