极海APM32F103配置定时器PWM频率不会随着系统时钟而变化
极海半导体推出的APM32F103系列在调试PWM波时，有时候会切换系统时钟，导致PWM的频率也变化；
在配置定时器时，通过获取定时器的时钟来配置定时器，可避免PWM频率随着系统时钟的变化而变化。

测试代码如下：
int main(void)
{
   GPIO_Config_T GPIO_ConfigStruct;
   TMR_BaseConfig_T TMR_TimeBaseStruct;
   TMR_OCConfig_T OCcongigStruct;


     //RCM_Reset();
     uint32_tpclk1_value=0,pclk2_value;
   RCM_ReadPCLKFreq(&pclk1_value,&pclk2_value);


   RCM_EnableAPB2PeriphClock((RCM_APB2_PERIPH_T)(RCM_APB2_PERIPH_GPIOA |RCM_APB2_PERIPH_TMR1 | RCM_APB2_PERIPH_GPIOB));


   GPIO_ConfigStruct.pin = GPIO_PIN_13;
    GPIO_ConfigStruct.mode= GPIO_MODE_AF_PP;
   GPIO_ConfigStruct.speed = GPIO_SPEED_50MHz;
   GPIO_Config(GPIOB, &GPIO_ConfigStruct);


   GPIO_ConfigStruct.pin = GPIO_PIN_8;
   GPIO_Config(GPIOA, &GPIO_ConfigStruct);


   TMR_TimeBaseStruct.clockDivision = TMR_CLOCK_DIV_1;
   TMR_TimeBaseStruct.countMode = TMR_COUNTER_MODE_UP;
  TMR_TimeBaseStruct.division = (pclk2_value/100000-1);
   //TMR_TimeBaseStruct.division =720-1;  
   TMR_TimeBaseStruct.period = 10-1;
   TMR_ConfigTimeBase(TMR1, &TMR_TimeBaseStruct);


   OCcongigStruct.idleState = TMR_OC_IDLE_STATE_RESET;
   OCcongigStruct.mode = TMR_OC_MODE_PWM1;
   OCcongigStruct.nIdleState = TMR_OC_NIDLE_STATE_RESET;
   OCcongigStruct.nPolarity = TMR_OC_NPOLARITY_HIGH;
   OCcongigStruct.outputNState = TMR_OC_NSTATE_ENABLE;
   OCcongigStruct.outputState = TMR_OC_STATE_ENABLE;
   OCcongigStruct.polarity = TMR_OC_POLARITY_HIGH;
   OCcongigStruct.pulse = 3;
    TMR_ConfigOC1(TMR1,&OCcongigStruct);


   TMR_ConfigOC1Preload(TMR1, TMR_OC_PRELOAD_ENABLE);
   TMR_EnableAutoReload(TMR1);



   TMR_Enable(TMR1);
     TMR_EnablePWMOutputs(TMR1);


    while(1)
    {
    }


}