STM32L4Rxxx 定时器使用

1、LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_TIM1);  

2、6.4.3  时钟配置寄存器 (RCC_CFGR) ，

PPRE2[2:0]：APB 高速预分频器 (APB2) (APB high-speed prescaler (APB2))

3、

/**
* @brief Return the PCLK2 frequency.
* @note Each time PCLK2 changes, this function must be called to update the
* right PCLK2 value. Otherwise, any configuration based on this function will be incorrect.
* @retval PCLK2 frequency in Hz
*/
uint32_t HAL_RCC_GetPCLK2Freq(void)
{
/* Get HCLK source and Compute PCLK2 frequency ---------------------------*/
return (HAL_RCC_GetHCLKFreq()>> (APBPrescTable[READ_BIT(RCC->CFGR, RCC_CFGR_PPRE2) >> RCC_CFGR_PPRE2_Pos] & 0x1FU));
}

PCLK2 对应 PPRE2