STM32F429 DMA serial port data transmission

Serial port data configuration

void macUART4_Config(void)

{

    GPIO_InitTypeDef GPIO_InitStructure;

  USART_InitTypeDef USART_InitStructure;

    RCC_AHB1PeriphClockCmd(macUART4_RX_GPIO_CLK|macUART4_TX_GPIO_CLK,ENABLE);

  RCC_APB1PeriphClockCmd(macUART4_CLK, ENABLE);

  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;  

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

  GPIO_InitStructure.GPIO_Pin =  macUART4_TX_PIN  ;  

  GPIO_Init(macUART4_TX_GPIO_PORT, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

  GPIO_InitStructure.GPIO_Pin =  macUART4_RX_PIN;

  GPIO_Init(macUART4_RX_GPIO_PORT, &GPIO_InitStructure);

GPIO_PinAFConfig(macUART4_RX_GPIO_PORT,macUART4_RX_SOURCE,macUART4_RX_AF);

  GPIO_PinAFConfig(macUART4_TX_GPIO_PORT,macUART4_TX_SOURCE,macUART4_TX_AF); 

  USART_InitStructure.USART_BaudRate = macUART4_BAUDRATE;

  USART_InitStructure.USART_WordLength = USART_WordLength_8b;

  USART_InitStructure.USART_StopBits = USART_StopBits_1;

  USART_InitStructure.USART_Parity = USART_Parity_No;

  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

  USART_Init(macUART4, &USART_InitStructure); 

  USART_Cmd(macUART4, ENABLE);

}

DMA configuration function, please compare with DMA serial port receiving data configuration function

void DMA_Config(void)

{

    DMA_InitTypeDef DMA_InitStructure;                //

    RCC_AHB1PeriphClockCmd(macUART4_DMA_CLK, ENABLE); //

    DMA_DeInit(macUART4_TX_DMA_STREAM);               //

  while (DMA_GetCmdStatus(macUART4_TX_DMA_STREAM) != DISABLE){

  } 

    DMA_InitStructure.DMA_Channel = macUART4_TX_DMA_CHANNEL;             //

  DMA_InitStructure.DMA_PeripheralBaseAddr = macUART4_DR_BASE;         //

  DMA_InitStructure.DMA_Memory0BaseAddr = (u32)SendBuff;               //

  DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;                //

  DMA_InitStructure.DMA_BufferSize = macUART4_SEND_BUFF_SIZE;          //

  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;     //

  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;                //

  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;   //

  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;        //

  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;                        //

  DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;                //

  DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;               // 

  DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;        //  

  DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;          //

  DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;  //

  DMA_Init(macUART4_TX_DMA_STREAM, &DMA_InitStructure);                   //     

  DMA_Cmd(macUART4_TX_DMA_STREAM, ENABLE);                                 

    while(DMA_GetCmdStatus(macUART4_TX_DMA_STREAM) != ENABLE)

  {

  }

}

Main function, debug serial port and UART4 send data at the same time, without affecting each other

int main(void)

{

    int i;

    SysTick_Init();

    NVIC_Configuration();

    Debug_USART_Config();

    macUART4_Config();

    DMA_Config();

    printf("Hello World!nn");

    for(i=0;i

  {

    SendBuff[i]  = 'A';

  }

    USART_DMACmd(macUART4, USART_DMAReq_Tx, ENABLE);

    while(1)

    {

        printf("Hello World!n");

    }

}

There is no interrupt routine involved in this program, and the use of DMA should avoid interrupts as much as possible.