尝试重现问题
由于客户使用的是主从架构，实验采用两块 STM3220G-EVAL 评估板来重现现象。 一块用来不间断发送串口数据， 另一块采
用串口 DMA 进行接收， 直接通过杜邦线连接串口 PIN 脚并共地，不使用评估板上的 RS232 收发器。 接收端使用
STM32F2xx_StdPeriph_Examples\ USART\USART_TwoBoards 的示例代码。 代码片段如下：
- int main(void)
- {
- ...
- USART_Config();
- ...
- while (1)
- {
- /* Clear Buffers */
- Fill_Buffer(RxBuffer, TXBUFFERSIZE);
- Fill_Buffer(CmdBuffer, 2);
- DMA_DeInit(USARTx_RX_DMA_STREAM);
- DMA_InitStructure.DMA_Channel = USARTx_RX_DMA_CHANNEL;
- DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
- /************* USART will receive the the transaction data ****************/
- /* Transaction data (length defined by CmdBuffer[1] variable) */
- DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)RxBuffer;
- DMA_InitStructure.DMA_BufferSize =10;// (uint16_t)CmdBuffer[1];
- DMA_InitStructure.DMA_Mode =DMA_Mode_Normal;//DMA_Mode_Circular;
- DMA_Init(USARTx_RX_DMA_STREAM, &DMA_InitStructure);
- NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream1_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
- NVIC_Init(&NVIC_InitStructure);
- /* Enable DMA Stream Transfer Complete interrupt */
- DMA_ITConfig(USARTx_RX_DMA_STREAM, DMA_IT_TE|DMA_IT_DME|DMA_IT_FE, ENABLE);
- /* Enable the DMA Stream */
- DMA_Cmd(USARTx_RX_DMA_STREAM, ENABLE);
- /* Enable the USART Rx DMA requests */
- USART_DMACmd(USARTx, USART_DMAReq_Rx , ENABLE);
- // USART_Cmd(USARTx, ENABLE);
- // while(SET ==USART_GetFlagStatus(USARTx,USART_FLAG_ORE))
- // {
- // Tmp =USART_ReceiveData(USARTx);
- // }
- while ((DMA_GetFlagStatus(USARTx_RX_DMA_STREAM, USARTx_RX_DMA_FLAG_TCIF) ==
- RESET)
- {
- }
- /* Clear all DMA Streams flags */
- DMA_ClearFlag(USARTx_RX_DMA_STREAM, USARTx_RX_DMA_FLAG_HTIF |
- USARTx_RX_DMA_FLAG_TCIF);
- /* Disable the DMA Stream */
- DMA_Cmd(USARTx_RX_DMA_STREAM, DISABLE);
- /* Disable the USART Rx DMA requests */
- USART_DMACmd(USARTx, USART_DMAReq_Rx, DISABLE);
- //handle the RxBuffer data...
- //...
- }
- }
- static void USART_Config(void)
- {
- USART_InitTypeDef USART_InitStructure;
- GPIO_InitTypeDef GPIO_InitStructure;
- /* Peripheral Clock Enable -------------------------------------------------*/
- /* Enable GPIO clock */
- RCC_AHB1PeriphClockCmd(USARTx_TX_GPIO_CLK | USARTx_RX_GPIO_CLK, ENABLE);
- /* Enable USART clock */
- USARTx_CLK_INIT(USARTx_CLK, ENABLE);
- /* Enable the DMA clock */
- RCC_AHB1PeriphClockCmd(USARTx_DMAx_CLK, ENABLE);
- /* USARTx GPIO configuration -----------------------------------------------*/
- /* Connect USART pins to AF7 */
- GPIO_PinAFConfig(USARTx_TX_GPIO_PORT, USARTx_TX_SOURCE, USARTx_TX_AF);
- GPIO_PinAFConfig(USARTx_RX_GPIO_PORT, USARTx_RX_SOURCE, USARTx_RX_AF);
- /* Configure USART Tx and Rx as alternate function push-pull */
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
- GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
- GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
- GPIO_InitStructure.GPIO_Pin = USARTx_TX_PIN;
- GPIO_Init(USARTx_TX_GPIO_PORT, &GPIO_InitStructure);
- GPIO_InitStructure.GPIO_Pin = USARTx_RX_PIN;
- GPIO_Init(USARTx_RX_GPIO_PORT, &GPIO_InitStructure);
- /* USARTx configuration ----------------------------------------------------*/
- /* Enable the USART OverSampling by 8 */
- USART_OverSampling8Cmd(USARTx, ENABLE);
- USART_InitStructure.USART_BaudRate = 1408000;//3750000;
- USART_InitStructure.USART_WordLength = USART_WordLength_8b;
- USART_InitStructure.USART_StopBits = USART_StopBits_1;
- /* When using Parity the word length must be configured to 9 bits */
- 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(USARTx, &USART_InitStructure);
- /* Configure DMA controller to manage USART TX and RX DMA request ----------*/
- DMA_InitStructure.DMA_PeripheralBaseAddr = USARTx_DR_ADDRESS;
- 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_Normal;
- DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
- DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
- DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
- DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
- DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
- /* Here only the unchanged parameters of the DMA initialization structure are
- configured. During the program operation, the DMA will be configured with
- different parameters according to the operation phase */
- /* Enable USART */
- USART_Cmd(USARTx, ENABLE);
- }
1 代码不做修改，若先启动接收端 MCU 再启动发送端 MCU， 接收端 MCU 的串口能正常接收。
2 代码不做修改，若先启动发送端 MCU 再启动接收端 MCU， 接收端 MCU 的串口 100%接收异常。
3 修改发送端代码，改为发送端 MCU 串口每 1 秒间隔发送一次，则无论启动顺序如何， 接收端 MCU 的串口都能正常。
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