STM8 TIM4 自动计算初始化函数

/*
  * @brief  Simple calulate square  number.
  * @param1  Base number
  * @param2  Exponent number       
  * @retval Number of base^number
  * @author: icerol
*/
unsigned long pow(uint base , uint exponent)
{
    uint temp = 1;
    for(uint i=0; i< exponent; i++)
    {
        temp *= base;
    }
    return  temp;
}

/*
  * @brief  Initial timer4 for base timer.
  * @param1  Timeout of microsecond
  * @retval None
  * @author: icerol
*/

void  timer4_Init(unsigned int microSecond)
{
    unsigned char pscr;
    double arr;
    double f_tim;
    for(pscr=0;pscr<0x08;pscr++)
    {
        f_tim = F_MASTER/pow(2,pscr);
        arr = microSecond/(1000000/f_tim);
        if(arr<0xff)
            break;
    }
    TIM4_PSCR_PSC = pscr;          //2^1 分频为1M 
    TIM4_ARR = (unsigned char)arr;        //每255us中断一次
    TIM4_IER = 0x01;         //允许更新中断
    TIM4_CR1 = 0x01;         //计数器使能，开始计数
}

#define   TIM4_OVR_UIF_vector         0x19
#pragma   vector = TIM4_OVR_UIF_vector
__interrupt void TIM4_OVR_UIF(void)
{
    TIM4_SR_UIF = 0;
    PD_ODR_ODR3 = !PD_ODR_ODR3;
}