Hi Leute, ich habe im Prinzip ein simples Problem. Ich möchte eine
einfache Idle Zeit Berechnung machen. Dafür setze ich im SysTick des
STM32f103TB alle 10ms eine counter Variable zurück. Diese ist natürlich
volatile.
Nun passiert aber manchmal, dass die Variable schlicht nicht zu 0
gesetzt wird, dann steht etwa das doppelte in "last_idle_counts".
Die memory Barriere war lediglich ein Versuch, der nix brachte.
Woran könnte das liegen?
main.c:
1 | #include "stm32f10x.h"
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2 |
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3 | static volatile uint32_t idle_counts = 0;
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4 | static const uint32_t idle_counts_max = 1; // max counts per systick if no task and interrupt is running. Reference value
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5 |
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6 |
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7 | int main ( void )
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8 | {
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9 |
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10 | // Init Clock
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11 | // Init_STM();
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12 | SystemInit();
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13 | ClockInit();
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14 | SystemCoreClockUpdate();
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15 |
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16 | SysTick_Config(SystemCoreClock/100); // each 10 ms
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17 |
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18 | while( 1 )
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19 | {
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20 | ++idle_counts;
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21 | }
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22 |
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23 | }
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24 |
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25 |
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26 | void ClockInit(void)
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27 | {
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28 | /* at this point HSI or HSE is the clock source, but no PLL */
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29 | RCC->CR |= RCC_CR_HSION;
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30 | while ((RCC->CR & RCC_CR_HSIRDY) != RCC_CR_HSIRDY); /* Wait until HSI ready */
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31 |
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32 | // disable pll, otherwise we cannot set the multiplier
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33 | RCC->CR &= ~RCC_CR_PLLON;
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34 | while ((RCC->CR & RCC_CR_PLLRDY) != 0); // wait until off
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35 |
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36 | // 8 MHz RC, 4 MHz * 16 = 64 MHz SYSCL = AHB = APB2, APB1 = HCLK/2 = 32 MHz, ADC = APB2/6 = 10.67 MHz; ADC 14 MHz max!
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37 | RCC->CFGR = 0x00000000;
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38 | RCC->CFGR |= RCC_CFGR_PLLSRC_HSI_Div2 | RCC_CFGR_PLLMULL16 | RCC_CFGR_PPRE1_DIV2 | RCC_CFGR_SW_PLL | RCC_CFGR_ADCPRE_DIV6;
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39 | while((RCC->CFGR & RCC_CFGR_SWS) == RCC_CFGR_SWS_PLL); // wait
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40 |
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41 | // enable PLL again
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42 | RCC->CR |= RCC_CR_PLLON;
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43 | while ((RCC->CR & RCC_CR_PLLRDY) == RCC_CR_PLLRDY); // wait until rdy
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44 |
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45 |
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46 | // prefetch enabled, 2 wait states
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47 | FLASH->ACR |= FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY_2;
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48 |
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49 | /* Check flash latency */
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50 | while ((FLASH->ACR & FLASH_ACR_LATENCY) != FLASH_ACR_LATENCY_2);
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51 | }
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52 |
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53 | void SysTick_Handler(void)
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54 | {
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55 | uint32_t last_idle_counts;
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56 |
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57 | static uint32_t idle_counts_mean;
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58 |
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59 | last_idle_counts = idle_counts;
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60 | idle_counts = 0;
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61 | __DMB();
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62 |
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63 | idle_counts_mean = (last_idle_counts + idle_counts_mean) / 2;
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64 | }
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Vielen Dank!
