一開始在stm32參考手冊裏找關於systick的內容，沒找到任何有用的信息，後來百度了下，發現是在cortex m3參考手冊裏有app
幾個寄存器的描述在第8.2節，寄存器的定義在core_cm3.h中而不是stm32f10.h，應該這個systick是屬於cm3內核的內容，因此才放在這個文件中定義。函數
先來看看是如何定義的：測試
/* Memory mapping of Cortex-M3 Hardware */ #define SCS_BASE (0xE000E000) /*!< System Control Space Base Address */ #define ITM_BASE (0xE0000000) /*!< ITM Base Address */ #define CoreDebug_BASE (0xE000EDF0) /*!< Core Debug Base Address */ #define SysTick_BASE (SCS_BASE + 0x0010) /*!< SysTick Base Address */ #define NVIC_BASE (SCS_BASE + 0x0100) /*!< NVIC Base Address */ #define SCB_BASE (SCS_BASE + 0x0D00) /*!< System Control Block Base Address */ #define InterruptType ((InterruptType_Type *) SCS_BASE) /*!< Interrupt Type Register */ #define SCB ((SCB_Type *) SCB_BASE) /*!< SCB configuration struct */ #define SysTick ((SysTick_Type *) SysTick_BASE) /*!< SysTick configuration struct */ #define NVIC ((NVIC_Type *) NVIC_BASE) /*!< NVIC configuration struct */ #define ITM ((ITM_Type *) ITM_BASE) /*!< ITM configuration struct */ #define CoreDebug ((CoreDebug_Type *) CoreDebug_BASE) /*!< Core Debug configuration struct */ #if defined (__MPU_PRESENT) && (__MPU_PRESENT == 1) #define MPU_BASE (SCS_BASE + 0x0D90) /*!< Memory Protection Unit */ #define MPU ((MPU_Type*) MPU_BASE) /*!< Memory Protection Unit */ #endif
能夠看到，中間有systick的定義，類型爲結構體指針，該結構體定義以下ui
typedef struct { __IO uint32_t CTRL; /*!< Offset: 0x00 SysTick Control and Status Register */ __IO uint32_t LOAD; /*!< Offset: 0x04 SysTick Reload Value Register */ __IO uint32_t VAL; /*!< Offset: 0x08 SysTick Current Value Register */ __I uint32_t CALIB; /*!< Offset: 0x0C SysTick Calibration Register */ } SysTick_Type;
能夠看到，systick相關的四個寄存器都定義了，後面還很方便的把各個爲的功能都用宏定義指明瞭，以下spa
/* SysTick Control / Status Register Definitions */ #define SysTick_CTRL_COUNTFLAG_Pos 16 /*!< SysTick CTRL: COUNTFLAG Position */ #define SysTick_CTRL_COUNTFLAG_Msk (1ul << SysTick_CTRL_COUNTFLAG_Pos) /*!< SysTick CTRL: COUNTFLAG Mask */ #define SysTick_CTRL_CLKSOURCE_Pos 2 /*!< SysTick CTRL: CLKSOURCE Position */ #define SysTick_CTRL_CLKSOURCE_Msk (1ul << SysTick_CTRL_CLKSOURCE_Pos) /*!< SysTick CTRL: CLKSOURCE Mask */ #define SysTick_CTRL_TICKINT_Pos 1 /*!< SysTick CTRL: TICKINT Position */ #define SysTick_CTRL_TICKINT_Msk (1ul << SysTick_CTRL_TICKINT_Pos) /*!< SysTick CTRL: TICKINT Mask */ #define SysTick_CTRL_ENABLE_Pos 0 /*!< SysTick CTRL: ENABLE Position */ #define SysTick_CTRL_ENABLE_Msk (1ul << SysTick_CTRL_ENABLE_Pos) /*!< SysTick CTRL: ENABLE Mask */ /* SysTick Reload Register Definitions */ #define SysTick_LOAD_RELOAD_Pos 0 /*!< SysTick LOAD: RELOAD Position */ #define SysTick_LOAD_RELOAD_Msk (0xFFFFFFul << SysTick_LOAD_RELOAD_Pos) /*!< SysTick LOAD: RELOAD Mask */ /* SysTick Current Register Definitions */ #define SysTick_VAL_CURRENT_Pos 0 /*!< SysTick VAL: CURRENT Position */ #define SysTick_VAL_CURRENT_Msk (0xFFFFFFul << SysTick_VAL_CURRENT_Pos) /*!< SysTick VAL: CURRENT Mask */ /* SysTick Calibration Register Definitions */ #define SysTick_CALIB_NOREF_Pos 31 /*!< SysTick CALIB: NOREF Position */ #define SysTick_CALIB_NOREF_Msk (1ul << SysTick_CALIB_NOREF_Pos) /*!< SysTick CALIB: NOREF Mask */ #define SysTick_CALIB_SKEW_Pos 30 /*!< SysTick CALIB: SKEW Position */ #define SysTick_CALIB_SKEW_Msk (1ul << SysTick_CALIB_SKEW_Pos) /*!< SysTick CALIB: SKEW Mask */ #define SysTick_CALIB_TENMS_Pos 0 /*!< SysTick CALIB: TENMS Position */ #define SysTick_CALIB_TENMS_Msk (0xFFFFFFul << SysTick_VAL_CURRENT_Pos) /*!< SysTick CALIB: TENMS Mask */ /*@}*/ /* end of group CMSIS_CM3_SysTick */
pos指明偏移位數，1ul的ul代表1爲unsigned long型數據，32位指針
接下來看看各個位的具體描述，先是控制寄存器code
重裝載寄存器裏面就放重裝載值blog
目前值寄存器就是保存目前值，最後一個校準沒用到。it
如下爲秒鐘的測試io
main部分代碼---------------- SysTick->CTRL&=~SysTick_CTRL_CLKSOURCE_Msk;//clksource清零 SysTick->CTRL|=SysTick_CTRL_CLKSOURCE_Msk;//clksource置1 SysTick->CTRL|=SysTick_CTRL_TICKINT_Msk;//開中斷 SysTick->LOAD=72000;//設置重裝載值 1ms SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk;//啓動systick while(1) { if(cnt==1000) { sec++; cnt=0; LCD_ShowNum(30,30,sec,10,12); } }
中斷部分，在stm32f10x_it.c
void SysTick_Handler(void) { extern u32 cnt; cnt++; }
剛剛發現，在core_cm3.h中已經有個函數用於設置systick，爲SysTick_Config