STM32F103 SysTick Timer Problems

[alexander23]

Posted on September 18, 2014 at 13:24

Hello community,

first of all I’m using the STM32F103RCT6, CooCox IDE 1.7.7 and ARM GCC 4.8.

 Now to my problem.

I’m trying to implement a task similar processing by using the Systick timer.

 I initialized the SysTick timer as follows:

uint32_t returnCode =

SysTick_Config

(8000);

if

(returnCode != 0) {

//

TODO

Error handling

}

SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8);

The System clock is set to PLL 64MHz. The AHB clock is also set to 64MHz.

I expect that every millisecond an interrupt is being triggered.

t=(8/64MHz)*8000 = 1ms.

Within the interrupt handler a timer value will be increased. volatile uint32_t timeMS = 0;

void

SysTick_Handler(

void

) {

       timeMS++;

}

Using the following function I’m trying to generate a task every 3 seconds. More accurately the inner function will be called every 3 seconds. The printf() function writes the values of the global and internal timers to the UART interface.

void

task1_handler(uint32_t timer){

static

uint32_t internalTimerCount = 0;

if

(timer >= (internalTimerCount + 3000)) {

             printf(

''Task1: GlobalTimer %d, IntTimer %d \r\n''

,timer, internalTimerCount);

             internalTimerCount = timer;

       }

}

 If i’m using this task_handler the inner function will be called every 6 seconds instead of expected 3 seconds.

I

don’t know

exactly where

the

error is or what I did wrong.

 I

hope you

can help

me.

This issue is driving me crazy.

Many thanks

Alex

[Tesla DeLorean]

Posted on September 18, 2014 at 14:10

  if (SysTick_Config(SystemCoreClock / 1000))

  {     /* Capture error */     while (1);   } Not sure how your SysTick interrupt, timeMS, interact with your other task and it's flow.