Hello,
i'm facing an issue regarding xtimer_usleep. This issue is not the same as
before which was preventing my task from waking up.
Here, my task stays awake but is stuck in a while loop that triggers my
watchdog.
Indeed, i found in this function : xtimer_spin_until(uint32_t target), that
i can stay permanently blocked in the first "while" :
xtimer_core.c :
*static inline void xtimer_spin_until(uint32_t target) {*
*#if XTIMER_MASK*
* target = _xtimer_lltimer_mask(target);*
*#endif*
* while (_xtimer_lltimer_now() > target);*
* while (_xtimer_lltimer_now() < target);*
*}*
By using GDB, i found that target was equal to 6 (or very small), so the
probability of the condition being false in order to get out of the loop is
very small and i stay blocked because each time the CPU evaluates the timer
counter, it has already overshoot the target value. I can easily reproduce
this issue by calling xtimer_usleep with very small values but i suppose it
is also likely it can occur with any kind of values.
Am i doing something wrong ? Is my analysis correct ? If yes, i don't know
how to solve this issue.
Here is my configuration :
*periph_conf.h :*
#define CLOCK_HSI (16000000U) /* internal oscillator */
#define CLOCK_CORECLOCK (16000000U) /* desired core clock
frequency */
/* configuration of PLL prescaler and multiply values */
/* CORECLOCK := HSI / CLOCK_PLL_DIV * CLOCK_PLL_MUL */
#define CLOCK_PLL_DIV RCC_CFGR_PLLDIV4
#define CLOCK_PLL_MUL RCC_CFGR_PLLMUL4
/* configuration of peripheral bus clock prescalers */
#define CLOCK_AHB_DIV RCC_CFGR_HPRE_DIV8 /* AHB clock -> 2MHz */
#define CLOCK_APB2_DIV RCC_CFGR_PPRE2_DIV1 /* APB2 clock -> 2MHz
*/
#define CLOCK_APB1_DIV RCC_CFGR_PPRE1_DIV1 /* APB1 clock -> 2MHz
*/
/* configuration of flash access cycles */
#define CLOCK_FLASH_LATENCY FLASH_ACR_LATENCY
/* bus clocks for simplified peripheral initialization, UPDATE MANUALLY! */
#define CLOCK_AHB (CLOCK_CORECLOCK / 8)
#define CLOCK_APB2 (CLOCK_CORECLOCK / 8)
#define CLOCK_APB1 (CLOCK_CORECLOCK / 8)
board.h :
*#define XTIMER_DEV TIMER_DEV(0)*
*#define XTIMER_CHAN (0)*
*#define XTIMER_WIDTH (16)*
*#define XTIMER_BACKOFF (100)*
*#define XTIMER_ISR_BACKOFF (100)*
*#define XTIMER_OVERHEAD (100)*
Thank you in advance for your help ;)
Regards,
--
*Aurélien FILLAU*
Co-founder at we-sens.com
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