SYD8801 systick tick timer 使用说明

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SYD8801 systick tick timer 使用说明

    和其他的以ARM MO为内核的MCU一样，SYD8801内部也有MO自带的systick tick timer，这里使用方法也十分简单。

    主函数如下：

//static void timer0_callback(void);
int main()
{
//    uint8_t i=0;
    led_config(LEDALL); 
    Systick_Init();
    
//    if(LPOCaliWaitUS(1000)){
//        for(i=0;i<6;i++){
//            led_turn(LEDALL);
//            delay_ms(300);
//        }
//    }else{
//        for(i=0;i<20;i++){
//            led_turn(LEDALL);
//            delay_ms(300);
//        }
//    }
//    
//    timer_0_enable(0x1F40, timer0_callback); // 8000 /32.768 ms =  244.140625 ms
    __enable_irq();
    while(1)
    {
    }
}
 void SysTick_Handler(void)
 {
      GPO_CTRL->GPO_7 = ~GPO_CTRL->GPO_7;
 }

    这里在主函数中初始化了systick tick timer，然后在其中断函数中翻转GPIO7这个管脚的状态

    其中初始化函数如下：

void Systick_Init(void)
{
//  if (SysTick_Config(SystemCoreClock / 1000))//1ºÁÃë
//  {
//    /* Capture error */
//    while (1);
//  }
//    
    if (SysTick_Config(SystemCoreClock))
  {
    /* Capture error */
    while (1);
  }
}
    systick tick timer的时钟就是MCU运行的时钟，传入的SystemCoreClock变量是定时器的分频值，其中SysTick_Config函数是MO自带函数，如下：

/**
  \brief   System Tick Configuration
  \details Initializes the System Timer and its interrupt, and starts the System Tick Timer.
           Counter is in free running mode to generate periodic interrupts.
  \param [in]  ticks  Number of ticks between two interrupts.
  \return          0  Function succeeded.
  \return          1  Function failed.
  \note    When the variable <b>__Vendor_SysTickConfig</b> is set to 1, then the
           function <b>SysTick_Config</b> is not included. In this case, the file <b><i>device</i>.h</b>
           must contain a vendor-specific implementation of this function.
 */
__STATIC_INLINE uint32_t SysTick_Config(uint32_t ticks)
{
  if ((ticks - 1UL) > SysTick_LOAD_RELOAD_Msk)
  {
    return (1UL);                                                   /* Reload value impossible */
  }

  SysTick->LOAD  = (uint32_t)(ticks - 1UL);                         /* set reload register */
  NVIC_SetPriority (SysTick_IRQn, (1UL << __NVIC_PRIO_BITS) - 1UL); /* set Priority for Systick Interrupt */
  SysTick->VAL   = 0UL;                                             /* Load the SysTick Counter Value */
  SysTick->CTRL  = SysTick_CTRL_CLKSOURCE_Msk |
                   SysTick_CTRL_TICKINT_Msk   |
                   SysTick_CTRL_ENABLE_Msk;                         /* Enable SysTick IRQ and SysTick Timer */
  return (0UL);                                                     /* Function successful */
}

   

    最后这里上传本博客使用到的源代码：http://download.csdn.net/detail/chengdong1314/9890438