stm32 學(xué)習筆記 systick定時(shí)器
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systick其實(shí)本為移植操作系統提供滴答時(shí)鐘的方便。
本文引用地址：http://dyxdggzs.com/article/201611/316276.htm前兩天再次接觸STM32，使用了V3.5的庫，突然發(fā)現繁瑣的Systick用法被簡(jiǎn)化成一句話(huà)。
即：
void SysTick_Configuration(void)
{
if (SysTick_Config(SystemCoreClock / 1000000))//72, 1us per tick
{
/* Capture error */
while (1);
}
}
而Systick_Config函數已經(jīng)取代了之前所有的設置過(guò)程。
systick.c文件也被簡(jiǎn)除，該函數直接歸在了內核文件core_cm3.h里面。
/* ################################## SysTick function ############################################ */
#if (!defined (__Vendor_SysTickConfig)) || (__Vendor_SysTickConfig == 0)
/**
* @brief Initialize and start the SysTick counter and its interrupt.
*
* @param ticks number of ticks between two interrupts
* @return 1 = failed, 0 = successful
*
* Initialise the system tick timer and its interrupt and start the
* system tick timer / counter in free running mode to generate
* periodical interrupts.
*/
static __INLINE uint32_t SysTick_Config(uint32_t ticks)
{
if (ticks > SysTick_LOAD_RELOAD_Msk) return (1); /* Reload value impossible */
SysTick->LOAD = (ticks & SysTick_LOAD_RELOAD_Msk) - 1; /* set reload register */
NVIC_SetPriority (SysTick_IRQn, (1<<__NVIC_PRIO_BITS) - 1); /* set Priority for Cortex-M0 System Interrupts */
SysTick->VAL = 0; /* Load the SysTick Counter Value */
SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk |
SysTick_CTRL_TICKINT_Msk |
SysTick_CTRL_ENABLE_Msk; /* Enable SysTick IRQ and SysTick Timer */
return (0); /* Function successful */
}
#endif
優(yōu)點(diǎn)是設置相當簡(jiǎn)化，
缺點(diǎn)是控制不如以前靈活了，一旦開(kāi)啟，確實(shí)沒(méi)有庫函數方便地重載或禁用。
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