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STM32F3 UART with DMA transmit max. 4 bytes

bm2
Associate III
Posted on January 02, 2015 at 18:32

Hello,

I've test the STM32F303 for using it in a new project. The configuration and libbrary are used from the CubeMX with the IAR compiler.

Now I can maximum transmit 4 bytes over the UART with one DMA transfer.

Here my configuration for the DMA and UART:

  huart2.Instance = USART2;

  huart2.Init.BaudRate = 57600;

  huart2.Init.WordLength = UART_WORDLENGTH_8B;

  huart2.Init.StopBits = UART_STOPBITS_1;

  huart2.Init.Parity = UART_PARITY_NONE;

  huart2.Init.Mode = UART_MODE_TX_RX;

  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;

  huart2.Init.OverSampling = UART_OVERSAMPLING_16;

  huart2.Init.OneBitSampling = UART_ONEBIT_SAMPLING_DISABLED ;

  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

    hdma_usart2_rx.Instance = DMA1_Channel6;

    hdma_usart2_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;

    hdma_usart2_rx.Init.PeriphInc = DMA_PINC_DISABLE;

    hdma_usart2_rx.Init.MemInc = DMA_MINC_ENABLE;

    hdma_usart2_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;

    hdma_usart2_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;

    hdma_usart2_rx.Init.Mode = DMA_NORMAL;

    hdma_usart2_rx.Init.Priority = DMA_PRIORITY_LOW;

    HAL_DMA_Init(&hdma_usart2_rx);

    __HAL_LINKDMA(huart,hdmarx,hdma_usart2_rx);

    hdma_usart2_tx.Instance = DMA1_Channel7;

    hdma_usart2_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;

    hdma_usart2_tx.Init.PeriphInc = DMA_PINC_DISABLE;

    hdma_usart2_tx.Init.MemInc = DMA_MINC_ENABLE;

    hdma_usart2_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;

    hdma_usart2_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;

    hdma_usart2_tx.Init.Mode = DMA_NORMAL;

    hdma_usart2_tx.Init.Priority = DMA_PRIORITY_LOW;

    HAL_DMA_Init(&hdma_usart2_tx);

    __HAL_LINKDMA(huart,hdmatx,hdma_usart2_tx);

I start the transmission with the function HAL_UART_Transmit_DMA (&huart2, pData, uSize);

When I call this function with uSize 1,2,3 or 4 works all fine. All values bigger than 4 have the same result as 4.

Have somebody a idea?

Thanks,

Bernd

1 REPLY 1
Posted on February 06, 2015 at 09:02

Hi moennicke.bernd,

Can you please provide the main.c file so that we reproduce your issue ?

Thank you,

Heisenberg.