STM32 system clock base timer

The STM32F10x core has a system clock base timer, which is a 24-bit down counter. After it is set and enabled, the count value decreases by 1 every time a system clock cycle passes. When the count value decreases to 0, the system time base timer will automatically reload the initial value.

The system time base timer generates an interrupt every 10ms.

Next, we will mainly introduce the library functions.

1. The function of SysTick_CLKSourceConfig is to set the clock source of SysClock. The input parameter is SysTick_CLKSource: SysTick clock source

The possible values ​​of the parameter are: SysTick_CLKSource_HCLK_Div8; SysTick_CLKSource_HCLK. Indicates that the SysTick clock source is the AHB clock divided by 8 and the AHB clock source.

Example: Set the system timer clock to AHB clock.

SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK);

2. The function of Sys_SetReload is to set the SysTick reload value. Its input parameter is a value between 32-bit 1 and 0x00FFFFF. (u32 Reload)

Example: Set the reload value of the system timer to 90000.

SysTick_SetReload(900000);

3. The function of SysTick_CounterCmd is to enable or disable the SysTick counter. Its input parameter is SysTick_Counter: the new state of the SysTick counter

The possible values ​​of the parameter are SysTick_Counter_Disable/Enable/Clear. Indicates disable, enable, clear counter value is 0.

Example: Enable the system timer.

SysTick_CounterCmd(SysTick_Counter_Enable);

4. The function of SysTick_ITconfig function is to enable or disable SysTick interrupt.

5. The function of SysTick_GetCounter is to get the value of SysTick counter.

Example: Get the count value of the system timer. It is a 32-bit value.

u32 SysTickCurrentCounterValue;

SysTickCurrentCounterValue = SysTick_GetCounter();