time定时器

代码下载地址：

https://download.csdn.net/download/qq_31806069/12567383

void timer_init(void)
{
    
    // Start 16 MHz crystal oscillator .
    NRF_CLOCK->EVENTS_HFCLKSTARTED  = 0;
    NRF_CLOCK->TASKS_HFCLKSTART     = 1;

    // Wait for the external oscillator to start up.
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) 
    {
        //Do nothing.
    }
    NRF_TIMER0->TASKS_STOP = 1;
    
    NVIC_EnableIRQ(TIMER0_IRQn);
    __enable_irq();
    NRF_TIMER0->TASKS_CLEAR = 1;
    NRF_TIMER0->SHORTS     = (TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos);
    NRF_TIMER0->MODE           = TIMER_MODE_MODE_Timer;     
    NRF_TIMER0->BITMODE        = TIMER_BITMODE_BITMODE_32Bit;  
    NRF_TIMER0->PRESCALER     = 4;//1M       
    NRF_TIMER0->INTENSET   = (TIMER_INTENSET_COMPARE0_Set << TIMER_INTENSET_COMPARE0_Pos);
    NRF_TIMER0->CC[0]         = 1000*1000;  

    
    NRF_TIMER0->TASKS_START    = 1;                    
    

}

void TIMER0_IRQHandler()
{
    if ((NRF_TIMER0->EVENTS_COMPARE[0] != 0) && 
       ((NRF_TIMER0->INTENSET & TIMER_INTENSET_COMPARE0_Msk) != 0))
    {
        // Sets the next CC1 value
        NRF_TIMER0->EVENTS_COMPARE[0] = 0;
        LED_TOG();
    }
}