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DMA to USART1 TX

Question asked by MAC on May 27, 2013
Latest reply on May 27, 2013 by MAC
Hi, i'm using smt32F303 discovery board, I send / receive data on USART1 without problem if I use interrupt mode, so I think that hardware is good.
I want send a data buffer lenght ~ 8000 bytes using dma mode. Before I config GPIO , USART, and  DMA , but on my hyperterminal receive only 4 chars , which is the problem?

this is my code:

unsigned char tx_buffer[8208];

void InitUSART1(void)
{
     GPIO_InitTypeDef      GPIO_InitStructure;
     NVIC_InitTypeDef             NVIC_InitStructure;
     USART_InitTypeDef               USART_InitStructure;
     
     // TX out mode
       GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
       GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
       GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
       GPIO_Init(GPIOC, &GPIO_InitStructure);
     // RX in mode
       GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
     GPIO_Init(GPIOC, &GPIO_InitStructure);
     
     /* Connect PXx to USARTx_Tx */
       GPIO_PinAFConfig(GPIOC,GPIO_PinSource4,GPIO_AF_7);
     GPIO_PinAFConfig(GPIOC,GPIO_PinSource5,GPIO_AF_7);
     
     /* Interrupt config */
  EXTI_InitStructure.EXTI_Line = EXTI_Line25; //usart1
       EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
       EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
       EXTI_InitStructure.EXTI_LineCmd = ENABLE;
       EXTI_Init(&EXTI_InitStructure);


  /* Enable and set EXTI0 Interrupt to the lowest priority */
       NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;     
       NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x07;
       NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x07;
       NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
       NVIC_Init(&NVIC_InitStructure);
     
     USART_InitStructure.USART_BaudRate = 57600;
     USART_InitStructure.USART_WordLength = USART_WordLength_8b;
     USART_InitStructure.USART_StopBits = USART_StopBits_1;
     USART_InitStructure.USART_Parity = USART_Parity_No;
     USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
     USART_InitStructure.USART_HardwareFlowControl =      USART_HardwareFlowControl_None;
     /* USART configuration */
     USART_Init(USART1, &USART_InitStructure);
     /* interrupt */
     USART_ITConfig(USART1,USART_IT_RXNE, ENABLE);
     /* Enable USART */
     USART_Cmd( USART1, ENABLE);
     /* Enable DMA tx USART */
     USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
     
}
 void SendBufferTx(void)
{
     DMA_InitTypeDef   DMA_InitStructure;
     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
     DMA_DeInit(DMA1_Channel4);
     DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->TDR;
     
     DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&tx_buffer;
     
       DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
       DMA_InitStructure.DMA_BufferSize = sizeof(tx_buffer);
       DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Enable;
       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_Mode = DMA_Mode_Normal;
       DMA_InitStructure.DMA_Priority = DMA_Priority_High;
       DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

       DMA_Init(DMA1_Channel4, &DMA_InitStructure);

     DMA_Cmd(DMA1_Channel4, ENABLE);     
}

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