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            EEPW首頁 > 嵌入式系統(tǒng) > 設(shè)計(jì)應(yīng)用 > stm32 系統(tǒng)嘀嗒(SysTick) 定時(shí)器

            stm32 系統(tǒng)嘀嗒(SysTick) 定時(shí)器

            作者: 時(shí)間:2016-11-13 來源:網(wǎng)絡(luò) 收藏
            系統(tǒng)嘀嗒校準(zhǔn)值固定為9000,當(dāng)系統(tǒng)嘀嗒時(shí)鐘設(shè)定為9MHz(HCLK/8的最大值),產(chǎn)生1ms時(shí)間基準(zhǔn)。
            在3.5 的庫中
            void SysTick_CLKSourceConfig(uint32_t SysTick_CLKSource)
            位于 misc.c 文件中
            然后在core_cm3.h 文件中,定義了一個(gè)內(nèi)聯(lián)函數(shù),完成定時(shí)配置,中斷開啟,定時(shí)器開啟的功能。
            /* ################################## SysTick function ############################################ */
            #if (!defined (__Vendor_SysTickConfig)) || (__Vendor_SysTickConfig == 0)
            /* SysTick constants */
            #define SYSTICK_ENABLE 0 /* Config-Bit to start or stop the SysTick Timer */
            #define SYSTICK_TICKINT 1 /* Config-Bit to enable or disable the SysTick interrupt */
            #define SYSTICK_CLKSOURCE 2 /* Clocksource has the offset 2 in SysTick Control and Status Register */
            #define SYSTICK_MAXCOUNT ((1<<24) -1) /* SysTick MaxCount */
            /**
            * @brief Initialize and start the SysTick counter and its interrupt.
            *
            * @param uint32_t ticks is the number of ticks between two interrupts
            * @return none
            *
            * 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_MAXCOUNT) return (1); /* Reload value impossible */
            SysTick->LOAD = (ticks & SYSTICK_MAXCOUNT) - 1; /* set reload register */
            NVIC_SetPriority (SysTick_IRQn, (1<<__NVIC_PRIO_BITS) - 1); /* set Priority for Cortex-M0 System Interrupts */
            SysTick->VAL = (0x00); /* Load the SysTick Counter Value */
            SysTick->CTRL = (1 << SYSTICK_CLKSOURCE) | (1<
            return (0); /* Function successful */
            }
            #endif
            老的庫文件的是6個(gè)函數(shù)
            1.void SysTick_CLKSourceConfig(uint32_t SysTick_CLKSource)
            下面的這幾個(gè)的功能都已經(jīng)被SysTick_Config() 所替代
            2.voidSysTick_SetReload(void)
            3.voidSysTick_CounterCmd(void)
            4.voidSysTick_ITConfig(void)
            5.voidSysTick_GetCounter(void)
            6.voidSysTick_GetFlagStatus(void)


            關(guān)鍵詞: stm32SysTick定時(shí)

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