GD32基于Systick实现us级和ms级的精准延时方案

/*!
    \file  systick.c
    \brief the systick configuration file
*/

/*
    Copyright (C) 2017 GigaDevice

    2014-12-26, V1.0.0, platform GD32F1x0(x=3,5)
    2016-01-15, V2.0.0, platform GD32F1x0(x=3,5,7,9)
    2016-04-30, V3.0.0, firmware update for GD32F1x0(x=3,5,7,9)
    2017-06-19, V3.1.0, firmware update for GD32F1x0(x=3,5,7,9)
*/

#include "gd32f1x0.h"
#include "systick.h"

volatile static float count_1us = 0;
volatile static float count_1ms = 0;

/*!
    \brief      configure systick
    \param[in]  none
    \param[out] none
    \retval     none
*/
void systick_config(void)
{
    /* systick clock source is from HCLK/8 */
    systick_clksource_set(SYSTICK_CLKSOURCE_HCLK_DIV8);
    count_1us = (float)SystemCoreClock/8000000;
    count_1ms = (float)count_1us * 1000;
}

/*!
    \brief      delay a time in microseconds in polling mode
    \param[in]  count: count in microseconds
    \param[out] none
    \retval     none
*/
void delay_1us(uint32_t count)
{
    uint32_t ctl;
    
    /* reload the count value */
    SysTick->LOAD = (uint32_t)(count * count_1us);
    /* clear the current count value */
    SysTick->VAL = 0x0000U;
    /* enable the systick timer */
    SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;
    /* wait for the COUNTFLAG flag set */
    do{
        ctl = SysTick->CTRL;
    }while((ctl&SysTick_CTRL_ENABLE_Msk)&&!(ctl & SysTick_CTRL_COUNTFLAG_Msk));
    /* disable the systick timer */
    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
    /* clear the current count value */
    SysTick->VAL = 0x0000U;
}

/*!
    \brief      delay a time in milliseconds in polling mode
    \param[in]  count: count in milliseconds
    \param[out] none
    \retval     none
*/
void delay_1ms(uint32_t count)
{
    uint32_t ctl;
    
    /* reload the count value */
    SysTick->LOAD = (uint32_t)(count * count_1ms);
    /* clear the current count value */
    SysTick->VAL = 0x0000U;
    /* enable the systick timer */
    SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;
    /* wait for the COUNTFLAG flag set */
    do{
        ctl = SysTick->CTRL;
    }while((ctl&SysTick_CTRL_ENABLE_Msk)&&!(ctl & SysTick_CTRL_COUNTFLAG_Msk));
    /* disable the systick timer */
    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
    /* clear the current count value */
    SysTick->VAL = 0x0000U;
}

标签：count,GD32,CTRL,systick,us,Msk,ms,SysTick,ctl
来源： https://blog.csdn.net/itdoy/article/details/113438209