GD32E230串口DMA发送接收

串口使用DMA可以节省MCU运行的时间，节省效率，把单片机内部资源用到最优化。串口DMA就是配置好初始化后，调用串口发送程序时先把要发送的数据保存到DMA缓存，然后使能DMA发送，接下来串口就由硬件自动发送数据，软件可以继续处理其他功能。
串口初始化分一下几个阶段：
·GPIO初始化
·串口初始化
·中断使能初始化
·DMA初始化

void Uart_Init(void)
{
/* initilize the com */
    com_gpio_init();
    com_usart_init();
    /*configure DMA interrupt*/
    nvic_config();
  TxRx_DMA_Config();
}

void com_gpio_init(void) //以串口0为例，gpio为PA9 PA10
{
rcu_periph_clock_enable(RCU_GPIOA);//使能IO口时钟
gpio_af_set(GPIOA, GPIO_AF_1, GPIO_PIN_9);//配置复用功能
gpio_af_set(GPIOA, GPIO_AF_1, GPIO_PIN_10);
/* configure USART Tx as alternate function push-pull */
    gpio_mode_set(GPIOA, GPIO_MODE_AF, GPIO_PUPD_PULLUP, GPIO_PIN_9);
    gpio_output_options_set(GPIOA, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ, GPIO_PIN_9);
   /* configure USART Rx as alternate function push-pull */
    gpio_mode_set(GPIOA, GPIO_MODE_AF, GPIO_PUPD_PULLUP, GPIO_PIN_10);
    gpio_output_options_set(GPIOA, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ, GPIO_PIN_10);
}

void com_usart_init(void)//串口初始化
{
/* enable USART clock */
    rcu_periph_clock_enable(RCU_USART0);//使能串口时钟
    /* USART configure */
    usart_deinit(USART0);
    usart_baudrate_set(USART0, 115200U);
    usart_receive_config(USART0, USART_RECEIVE_ENABLE);
    usart_transmit_config(USART0, USART_TRANSMIT_ENABLE);
    usart_enable(USART0);
}

void nvic_config(void)
{
nvic_irq_enable(DMA_Channel1_2_IRQn, 0);
}

void TxRx_DMA_Config(void)//DMA发送接收初始化
{
dma_parameter_struct dma_init_struct;
    /* enable DMA clock */
    rcu_periph_clock_enable(RCU_DMA);
 /* initialize DMA channel1 */
    dma_deinit(DMA_CH1);
    dma_struct_para_init(&dma_init_struct);
    dma_init_struct.direction = DMA_MEMORY_TO_PERIPHERAL;
    dma_init_struct.memory_addr = (uint32_t)txbuffer;
    dma_init_struct.memory_inc = DMA_MEMORY_INCREASE_ENABLE;
    dma_init_struct.memory_width = DMA_MEMORY_WIDTH_8BIT;
    dma_init_struct.number = TX_BUF_LEN;
    dma_init_struct.periph_addr = USART0_TDATA_ADDRESS;
    dma_init_struct.periph_inc = DMA_PERIPH_INCREASE_DISABLE;
    dma_init_struct.periph_width = DMA_PERIPHERAL_WIDTH_8BIT;
    dma_init_struct.priority = DMA_PRIORITY_ULTRA_HIGH;
    dma_init(DMA_CH1, &dma_init_struct);
    /* initialize DMA channel2 */
    dma_deinit(DMA_CH2);
    dma_init_struct.direction = DMA_PERIPHERAL_TO_MEMORY;
    dma_init_struct.memory_addr = (uint32_t)rxbuffer;
    dma_init_struct.memory_inc = DMA_MEMORY_INCREASE_ENABLE;
    dma_init_struct.memory_width = DMA_MEMORY_WIDTH_8BIT;
    dma_init_struct.number = RX_BUF_LEN;
    dma_init_struct.periph_addr = USART0_RDATA_ADDRESS;
    dma_init_struct.periph_inc = DMA_PERIPH_INCREASE_DISABLE;
    dma_init_struct.memory_width = DMA_PERIPHERAL_WIDTH_8BIT;
    dma_init_struct.priority = DMA_PRIORITY_ULTRA_HIGH;
    dma_init(DMA_CH2, &dma_init_struct);
    /* configure DMA mode */
    dma_circulation_disable(DMA_CH1);
    dma_memory_to_memory_disable(DMA_CH1);
    dma_circulation_disable(DMA_CH2);
    dma_memory_to_memory_disable(DMA_CH2);
    /* USART DMA enable for reception */
    usart_dma_receive_config(USART0, USART_DENR_ENABLE);
    /* enable DMA channel2 transfer complete interrupt */
    dma_interrupt_enable(DMA_CH2, DMA_INT_FTF);
    /* enable DMA channel2 */
    dma_channel_enable(DMA_CH2);
    /* USART DMA enable for transmission */
    usart_dma_transmit_config(USART0, USART_DENT_ENABLE);
    /* enable DMA channel1 transfer complete interrupt */
    dma_interrupt_enable(DMA_CH1, DMA_INT_FTF);
    /* enable DMA channel1 */
    dma_channel_enable(DMA_CH1);
}

```c
void Use_DMA_SendTX1_Data(uint8_t *buffter, uint8_t writeLen)
{//串口DMA发送函数，发送数据时调用这个函数，发送完成后会产生一个中断
uint8 i;//, Tx_Buf1[64];
 dma_parameter_struct dma_init_struct;
 for (i = 0; i < writeLen; i ++)
 {
  txbuffer[i] = buffter[i];
 }
 dma_channel_disable(DMA_CH1);
 dma_memory_address_config(DMA_CH1, (uint32)txbuffer);
 
 dma_transfer_number_config(DMA_CH1, (uint32_t)writeLen);
 /* enable DMA channel1 */
  dma_channel_enable(DMA_CH1);
 /* USART DMA enable for transmission */
  usart_dma_transmit_config(USART0, USART_DENT_ENABLE);
}

void DMA_Channel1_2_IRQHandler(void)//发送接收通道中断处理
{
static uint32 Rx_num;
    if(RESET != dma_interrupt_flag_get(DMA_CH1, DMA_INT_FLAG_FTF)){
        dma_interrupt_flag_clear(DMA_CH1, DMA_INT_FLAG_G);
    }
    if(RESET != dma_interrupt_flag_get(DMA_CH2, DMA_INT_FLAG_FTF)){
    dma_channel_disable(DMA_CH2);
        dma_interrupt_flag_clear(DMA_CH2, DMA_INT_FLAG_G);
    dma_flag_clear(DMA_CH2, DMA_FLAG_G);
    Rx_num = dma_transfer_number_get(DMA_CH2);
    dma_transfer_number_config(DMA_CH2,RX_BUF_LEN);
    dma_channel_enable(DMA_CH2);
    }
}

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