UART9串口，发送波特率是接收的一半，才能通信。比如单片机波特率设为9600，串口助手19200才能正常通信，否则乱码

yuanzinpl · 发表于 2021-9-9 15:27:32

使用HAL库函数，我遇到问题是其他串口正常，只有UART9串口，发送波特率是接收的一半，才能通信。比如单片机波特率设为9600，串口助手19200才能正常通信，否则乱码。同一个原子例程模板改的，串口1，2,6,7,8都是正常相同的波特率

yuanzinpl · 发表于 2021-9-9 15:27:33

本帖最后由 yuanzinpl 于 2021-9-11 17:01 编辑

找到原因了,HAL库函数中没有考虑UART9和UART10这两种串口的情形，只把USART1和USART6按照所在的APB2时钟设置波特率了，UART9和UART10也在APB2时钟下面。但是没考虑UART9和UART10，程序中除了USART1和USART6，其他串口都按照最后的else情况，按照APB1时钟设置了，时钟差别2倍关系，BRR按照APB1设置，实际UART9，UART10时钟确是APB2，所以波特率也是2倍关系。详情查看UART_SetConfig(UART_HandleTypeDef *huart)
iif(huart->Init.OverSampling == UART_OVERSAMPLING_8)  {
/*-------------------------- USART BRR Configuration ---------------------*/
#if defined(USART6)
if((huart->Instance == USART1) || (huart->Instance == USART6))
{
   huart->Instance->BRR = UART_BRR_SAMPLING8(HAL_RCC_GetPCLK2Freq(), huart->Init.BaudRate);
}
#else
if(huart->Instance == USART1)
{
   huart->Instance->BRR = UART_BRR_SAMPLING8(HAL_RCC_GetPCLK2Freq(), huart->Init.BaudRate);
}
#endif /* USART6 */
    else
{
   huart->Instance->BRR = UART_BRR_SAMPLING8(HAL_RCC_GetPCLK1Freq(), huart->Init.BaudRate);
}
  }
  else
  {
/*-------------------------- USART BRR Configuration ---------------------*/
#if defined(USART6)
if((huart->Instance == USART1) || (huart->Instance == USART6))
{
   huart->Instance->BRR = UART_BRR_SAMPLING16(HAL_RCC_GetPCLK2Freq(), huart->Init.BaudRate);
}
#else
if(huart->Instance == USART1)
{
   huart->Instance->BRR = UART_BRR_SAMPLING16(HAL_RCC_GetPCLK2Freq(), huart->Init.BaudRate);
}
#endif /* USART6 */
else
{
   huart->Instance->BRR = UART_BRR_SAMPLING16(HAL_RCC_GetPCLK1Freq(), huart->Init.BaudRate);
}
  }

USART1 APB2

USART2 APB1

USART3 APB1

UART4    APB1

UART5    APB1

USART6 APB2

UART7    APB1

UART8    APB1

UART9    APB2

UART10    APB2

根据串口初始化函数推测，HAL库函数确是没有专门针对UAR9，UART10进行设置
大部分参数This parameter can be UARTx where x: 1, 2, 3, 4, 5, 6, 7 or 8 to select the USART or *       UART peripheral.

后来发现STM32CUBE生成的UART9代码工程中对应的HAL库函数就增加了UART9，UART10这两种串口如下
static void UART_SetConfig(UART_HandleTypeDef *huart)
{
uint32_t tmpreg;
uint32_t pclk;
/* Check the parameters */
assert_param(IS_UART_BAUDRATE(huart->Init.BaudRate));
assert_param(IS_UART_STOPBITS(huart->Init.StopBits));
assert_param(IS_UART_PARITY(huart->Init.Parity));
assert_param(IS_UART_MODE(huart->Init.Mode));
/*-------------------------- USART CR2 Configuration -----------------------*/
/* Configure the UART Stop Bits: Set STOP[13:12] bits
   according to huart->Init.StopBits value */
MODIFY_REG(huart->Instance->CR2, USART_CR2_STOP, huart->Init.StopBits);
/*-------------------------- USART CR1 Configuration -----------------------*/
/* Configure the UART Word Length, Parity and mode:
   Set the M bits according to huart->Init.WordLength value
   Set PCE and PS bits according to huart->Init.Parity value
   Set TE and RE bits according to huart->Init.Mode value
   Set OVER8 bit according to huart->Init.OverSampling value */
tmpreg = (uint32_t)huart->Init.WordLength | huart->Init.Parity | huart->Init.Mode | huart->Init.OverSampling;
MODIFY_REG(huart->Instance->CR1,
            (uint32_t)(USART_CR1_M | USART_CR1_PCE | USART_CR1_PS | USART_CR1_TE | USART_CR1_RE | USART_CR1_OVER8),
            tmpreg);
/*-------------------------- USART CR3 Configuration -----------------------*/
/* Configure the UART HFC: Set CTSE and RTSE bits according to huart->Init.HwFlowCtl value */
MODIFY_REG(huart->Instance->CR3, (USART_CR3_RTSE | USART_CR3_CTSE), huart->Init.HwFlowCtl);

#if defined(USART6) && defined(UART9) && defined(UART10)
   if ((huart->Instance == USART1) || (huart->Instance == USART6) || (huart->Instance == UART9) || (huart->Instance == UART10))
   {
   pclk = HAL_RCC_GetPCLK2Freq();
   }
#elif defined(USART6)
   if ((huart->Instance == USART1) || (huart->Instance == USART6))
   {
   pclk = HAL_RCC_GetPCLK2Freq();
   }
#else
   if (huart->Instance == USART1)
   {
   pclk = HAL_RCC_GetPCLK2Freq();
   }
#endif /* USART6 */
   else
   {
   pclk = HAL_RCC_GetPCLK1Freq();
   }
/*-------------------------- USART BRR Configuration ---------------------*/
if (huart->Init.OverSampling == UART_OVERSAMPLING_8)
{
   huart->Instance->BRR = UART_BRR_SAMPLING8(pclk, huart->Init.BaudRate);
}
else
{
   huart->Instance->BRR = UART_BRR_SAMPLING16(pclk, huart->Init.BaudRate);
}
}

lpwithv · 发表于 2021-9-9 16:37:13

感觉是你时钟的问题

yuanzinpl · 发表于 2021-9-9 16:40:37

补充下UART9的寄存器设置是正确的，本想截图，但是却不能添加图片。寄存器设置和UART8波特率9600时候的寄存器设置对比了是相同的

yuanzinpl · 发表于 2021-9-9 16:41:20

lpwithv 发表于 2021-9-9 16:37
感觉是你时钟的问题

系统时钟都是和其他例程相同的

jermy_z · 发表于 2021-9-10 08:54:28

直接用cubemx生成一个串口9的初始化代码试试，我也感觉是你时钟问题

远命 · 发表于 2021-9-10 09:04:53

/*---------------------------- USART BRR Configuration -----------------------*/
  /* Configure the USART Baud Rate */
  RCC_GetClocksFreq(&RCC_ClocksStatus);

  if ((USARTx == USART1) || (USARTx == USART6))
  {
apbclock = RCC_ClocksStatus.PCLK2_Frequency;
  }
  else
  {
apbclock = RCC_ClocksStatus.PCLK1_Frequency;
  }

  /* Determine the integer part */
  if ((USARTx->CR1 & USART_CR1_OVER8) != 0)
  {
/* Integer part computing in case Oversampling mode is 8 Samples */
integerdivider = ((25 * apbclock) / (2 * (USART_InitStruct->USART_BaudRate)));
  }
  else /* if ((USARTx->CR1 & USART_CR1_OVER8) == 0) */
  {
/* Integer part computing in case Oversampling mode is 16 Samples */
integerdivider = ((25 * apbclock) / (4 * (USART_InitStruct->USART_BaudRate)));
  }
  tmpreg = (integerdivider / 100) << 4;

你看看这一段