{

if (ticks > SYSTICK_MAXCOUNT) return (1); /* Reload value impossible */

SysTick->LOAD = (ticks & SYSTICK_MAXCOUNT) - 1; /* set reload register */

NVIC_SetPriority (SysTick_IRQn, (1<<__NVIC_PRIO_BITS) - 1); /* set Priority for Cortex-M0 System Interrupts */

SysTick->VAL = (0x00); /* Load the SysTick Counter Value */

SysTick->CTRL = (1 << SYSTICK_CLKSOURCE) | (1<

return (0); /* Function successful */

}

void SysTick_Initial(u16 periodtimer)

{

SysTick_Config(periodtimer);

SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8); // 分頻放在配置后面，不然分頻不起效果

}