STM32L1XX使用HAL_UART_Transmit_DMA發送串口資料

標籤：

使用STM32CubeMX產生初始化代碼。

問題：

HAL_UART_Transmit_DMA函數只能調用一次，第二次就返回狀態HAL_UART_STATE_BUSY 0x02。

原因：

stm32l1xx_hal_uart.c開頭有描述

        (##) DMA Configuration if you need to use DMA process (HAL_UART_Transmit_DMA()
             and HAL_UART_Receive_DMA() APIs):
            (+++) Declare a DMA handle structure for the Tx/Rx channel.
            (+++) Enable the DMAx interface clock.
            (+++) Configure the declared DMA handle structure with the required 
                  Tx/Rx parameters.                
            (+++) Configure the DMA Tx/Rx channel.
            (+++) Associate the initialized DMA handle to the UART DMA Tx/Rx handle.
            (+++) Configure the priority and enable the NVIC for the transfer complete 
                  interrupt on the DMA Tx/Rx channel.
            (+++) Configure the USARTx interrupt priority and enable the NVIC USART IRQ handle
                  (used for last byte sending completion detection in DMA non circular mode)

配置USARTx中斷優先順序，啟用NVIC USART中斷控制代碼（使用DMA非迴圈模式時，用來檢測最後一個位元組發送完畢）

預設 USART1的全域中斷未Checked。

或者：

在發送結束的回呼函數中，恢複uart的Ready狀態。

void HAL_UART_TxHalfCpltCallback(UART_HandleTypeDef *huart)
{
//回呼函數
huart->State=HAL_UART_STATE_READY; 


}

下面附的是mbed-os的代碼，它的UART_DMATransmitCplt函數直接複位Uart的狀態了。

/**  * @brief DMA UART transmit process complete callback   * @param hdma: DMA handle  * @retval None  */01523 static void UART_DMATransmitCplt(DMA_HandleTypeDef *hdma)     {  UART_HandleTypeDef* huart = ( UART_HandleTypeDef* )((DMA_HandleTypeDef* )hdma)->Parent;  huart->TxXferCount = 0;    /* Disable the DMA transfer for transmit request by setting the DMAT bit  in the UART CR3 register */  huart->Instance->CR3 &= (uint32_t)~((uint32_t)USART_CR3_DMAT);    /* Wait for UART TC Flag */  if(UART_WaitOnFlagUntilTimeout(huart, UART_FLAG_TC, RESET, HAL_UART_TXDMA_TIMEOUTVALUE) != HAL_OK)  {    /* Timeout Occured */     huart->State = HAL_UART_STATE_TIMEOUT;    HAL_UART_ErrorCallback(huart);  }  else  {    /* No Timeout */    /* Check if a receive process is ongoing or not */    if(huart->State == HAL_UART_STATE_BUSY_TX_RX)     {      huart->State = HAL_UART_STATE_BUSY_RX;    }    else    {      <span style="color:#cc0000;">huart->State = HAL_UART_STATE_READY;</span>    }    HAL_UART_TxCpltCallback(huart);  }}

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STM32L1XX使用HAL_UART_Transmit_DMA發送串口資料