写一个GD32F303通过DMA发送串口中断接受的RS485串口DMA函数

好的，下面是一个GD32F303通过DMA发送串口中断接收的RS485串口DMA函数的示例代码：

#include "gd32f30x.h"

#define USART USART1
#define USART_DMA_CHANNEL DMA_CH5
#define USART_DMA_STREAM DMA0_STREAM5

#define BUFFER_SIZE 128

uint8_t tx_buffer[BUFFER_SIZE];
uint8_t rx_buffer[BUFFER_SIZE];
uint16_t rx_len = 0;

void rs485_init(void)
{
    rcu_periph_clock_enable(RCU_USART1);
    rcu_periph_clock_enable(RCU_AF);

    gpio_init(GPIOA, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_9);
    gpio_init(GPIOA, GPIO_MODE_AF_OD, GPIO_OSPEED_50MHZ, GPIO_PIN_10);

    usart_deinit(USART);

    usart_baudrate_set(USART, 9600);
    usart_parity_config(USART, USART_PM_NONE);
    usart_word_length_set(USART, USART_WL_8BIT);
    usart_stop_bit_set(USART, USART_STB_1BIT);
    usart_hardware_flow_rts_config(USART, USART_RTS_DISABLE);
    usart_hardware_flow_cts_config(USART, USART_CTS_DISABLE);

    usart_transmit_config(USART, USART_TRANSMIT_ENABLE);
    usart_receive_config(USART, USART_RECEIVE_ENABLE);

    usart_enable(USART);

    nvic_irq_enable(USART1_IRQn, 0, 0);
}

void rs485_dma_init(void)
{
    rcu_periph_clock_enable(RCU_DMA0);

    dma_deinit(USART_DMA_STREAM);

    dma_parameter_struct dma_init_struct;
    dma_init_struct.direction = DMA_MEMORY_TO_PERIPHERAL;
    dma_init_struct.memory_addr = (uint32_t)tx_buffer;
    dma_init_struct.memory_inc = DMA_MEMORY_INC_ENABLE;
    dma_init_struct.memory_width = DMA_MEMORY_WIDTH_8BIT;
    dma_init_struct.periph_addr = (uint32_t)&USART_DATA(USART);
    dma_init_struct.periph_inc = DMA_PERIPH_INC_DISABLE;
    dma_init_struct.periph_width = DMA_PERIPHERAL_WIDTH_8BIT;
    dma_init_struct.priority = DMA_PRIORITY_HIGH;
    dma_init(USART_DMA_STREAM, dma_init_struct);

    dma_circulation_disable(USART_DMA_STREAM);
    dma_memory_to_memory_disable(USART_DMA_STREAM);

    dma_channel_subperipheral_select(USART_DMA_STREAM, DMA_SUBPERI0_USART1_TX);

    usart_dma_transmit_config(USART, USART_DMA_CHANNEL, USART_DENT_ENABLE);

    dma_interrupt_enable(USART_DMA_STREAM, DMA_INT_FTF);

    nvic_irq_enable(DMA0_Channel5_IRQn, 0, 0);
}

void rs485_send_dma(uint8_t *buffer, uint16_t len)
{
    memcpy(tx_buffer, buffer, len);

    dma_transfer_number_config(USART_DMA_STREAM, len);
    dma_memory_address_config(USART_DMA_STREAM, (uint32_t)tx_buffer);

    dma_channel_enable(USART_DMA_STREAM);
}

void rs485_receive_dma(void)
{
    rx_len = 0;

    dma_transfer_number_config(USART_DMA_STREAM, BUFFER_SIZE);
    dma_memory_address_config(USART_DMA_STREAM, (uint32_t)rx_buffer);

    dma_channel_enable(USART_DMA_STREAM);
}

void USART1_IRQHandler(void)
{
    if (usart_interrupt_flag_get(USART, USART_INT_FLAG_RBNE))
    {
        uint8_t data = usart_data_receive(USART);
        // 处理接收到的数据

        if (rx_len < BUFFER_SIZE)
        {
            rx_buffer[rx_len++] = data;
        }
    }
}

void DMA0_Channel5_IRQHandler(void)
{
    if (dma_interrupt_flag_get(DMA0, DMA_CH5, DMA_INT_FLAG_FTF))
    {
        dma_interrupt_flag_clear(DMA0, DMA_CH5, DMA_INT_FLAG_FTF);

        dma_channel_disable(USART_DMA_STREAM);
    }
}

这个示例代码中，我们使用了DMA来发送和接收RS485串口数据。在初始化函数 `rs485_dma_init()` 中，我们配置了USART的DMA传输通道，并设置了DMA的参数。在发送函数 `rs485_send_dma()` 中，我们将要发送的数据拷贝到发送缓冲区，并启动DMA传输。在接收函数 `rs485_receive_dma()` 中，我们启动DMA接收。

同时，我们也实现了USART和DMA的中断处理函数 `USART1_IRQHandler()` 和 `DMA0_Channel5_IRQHandler()`，用于处理接收和发送完成的中断事件。

希望这个示例对你有帮助！如果有任何问题，请随时提问。