0x01 GPIO時鐘使能的坑

使用GD32的GPIO引腳來控制 74HC595 ，發現引腳一直無法控制，始終輸出3.3v，初始化環節應該是出了問題。用通俗的話來說，就是點燈點不亮

排查了MCU、光耦隔離芯片、被強行上拉等問題，最后發現是GD的GPIO時鐘使能問題。

以下是錯誤使用方法：

    rcu_periph_clock_enable(RCU_SER | RCU_SCK);

修改為以下方法即可：

    rcu_periph_clock_enable(RCU_SER);rcu_periph_clock_enable(RCU_SCK);

日后想必也會經常需要驗證GD32，留個點燈函數在這里

rcu_periph_clock_enable(RCU_GPIOC);
gpio_mode_set(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN_13);
gpio_output_options_set(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_13);gpio_bit_set(GPIOC,GPIO_PIN_13);
gpio_bit_reset(GPIOC,GPIO_PIN_13);

0x02 微秒級延時函數

systick.c

#include "gd32f1x0.h"
#include "systick.h"volatile static uint32_t delay;#include "systick.h"volatile static float count_1us = 0;
volatile static float count_1ms = 0;void delay_decrement(void)
{if (0U != delay){delay--;}
}void systick_config(void)
{/* systick clock source is from HCLK/8 內部時鐘的108M/8分頻 */systick_clksource_set(SYSTICK_CLKSOURCE_HCLK_DIV8);count_1us = (float)SystemCoreClock/12000000;//延時1us需要的時鐘數量 108M/8M = 13.5 count_1ms = (float)count_1us * 1000;//延時1ms需要的時鐘數量 108M/8M *1000= 13500 
}void delay_1us(uint32_t count)
{uint32_t ctl;SysTick->LOAD = (uint32_t)(count * count_1us);SysTick->VAL = 0x0000U;SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;do{ctl = SysTick->CTRL;}while((ctl&SysTick_CTRL_ENABLE_Msk)&&!(ctl & SysTick_CTRL_COUNTFLAG_Msk));SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;SysTick->VAL = 0x0000U;
}void delay_1ms(uint32_t count)
{uint32_t ctl;SysTick->LOAD = (uint32_t)(count * count_1ms);SysTick->VAL = 0x0000U;SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;do{ctl = SysTick->CTRL;}while((ctl&SysTick_CTRL_ENABLE_Msk)&&!(ctl & SysTick_CTRL_COUNTFLAG_Msk));SysTick->VAL = 0x0000U;
}

systick.h

#ifndef SYSTICK_H
#define SYSTICK_H#include <stdint.h>void systick_config(void);
void delay_1ms(uint32_t count);
void delay_1us(uint32_t count);
void delay_decrement(void);#endif