gd32f3x0系列串口例程

以下是GD32F3x0系列MCU的串口例程，您可以参考以下代码：

#include "gd32f3x0.h"
#include <stdio.h>

#define USART0 USART0_BASE

void usart0_init(void);
void usart0_send_char(char ch);
void usart0_send_string(char *str);

int main(void)
{
    usart0_init();
    usart0_send_string("Hello, world!\r\n");

    while (1) {
        /* Do something */
    }

    return 0;
}

void usart0_init(void)
{
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_USART0);

    gpio_af_set(GPIOA, GPIO_AF_1, GPIO_PIN_2 | GPIO_PIN_3);

    gpio_mode_set(GPIOA, GPIO_MODE_AF, GPIO_PUPD_PULLUP, GPIO_PIN_2 | GPIO_PIN_3);
    gpio_output_options_set(GPIOA, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_2 | GPIO_PIN_3);

    usart_deinit(USART0);
    usart_baudrate_set(USART0, 115200U);
    usart_word_length_set(USART0, USART_WL_8BIT);
    usart_stop_bit_set(USART0, USART_STB_1BIT);
    usart_parity_config(USART0, USART_PM_NONE);
    usart_hardware_flow_rts_config(USART0, USART_RTS_DISABLE);
    usart_hardware_flow_cts_config(USART0, USART_CTS_DISABLE);
    usart_receive_config(USART0, USART_RECEIVE_ENABLE);
    usart_transmit_config(USART0, USART_TRANSMIT_ENABLE);
    usart_enable(USART0);
}

void usart0_send_char(char ch)
{
    usart_data_transmit(USART0, (uint8_t)ch);
    while (usart_flag_get(USART0, USART_FLAG_TBE) == RESET);
}

void usart0_send_string(char *str)
{
    while (*str) {
        usart0_send_char(*str++);
    }
}