xc_drv_systick.c

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/*-----------------------------------------------------------------------------------
                                       INCLUDE HEADE FILES
 ------------------------------------------------------------------------------------*/
#include "xc_drv_systick.h"
#include "xc_drv_clock.h"
 
/*------------------------------------------------------------------------------------
                                            Functions
 -------------------------------------------------------------------------------------*/
 
void SysTick_Handler(void) { systick_callback(); }
 
void delay_us(uint32_t nus)
{
    if (nus == 0)
        return;
 
    uint32_t unit = xc_systick_unit_get();
 
    uint32_t temp;
 
    SysTick->CTRL = 0x00; // 关闭计数器
    SysTick->LOAD = unit * nus - unit + 1;
 
    SysTick->VAL  = 0;
    SysTick->CTRL = 0x05;
 
    do {
        temp = SysTick->CTRL; // 读取当前倒计数值
    } while ((temp & 0x01) && (!(temp & (1 << 16))));
}
 
void delay_ms(uint32_t nms)
{
    if (nms == 0) {
        return;
    }
 
    do {
        delay_us(1000);
    } while (--nms);
}
 
__WEAK void systick_callback(void) {}