stm32波特率的计算公式

Question

在stm32中如何设置波特率？即波特率是如何计算的？在设置波特率的过程中出现问题，求解答，谢谢！

Answer 1

以串口1的为例，库函数操作：

 //串口初始化函数，输入参数波特率，一般是9600
void USART1_InitConfig(uint32 BaudRate)
{
   USART_InitTypeDef USART_InitStructure;
   NVIC_InitTypeDef NVIC_InitStructure; 

   //使能串口的RCC时钟
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

   //串口使用的GPIO口配置
   //设置USART1 Rx (PA.10)为悬浮输入
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
   GPIO_Init(GPIOA, &GPIO_InitStructure);

   //设置 USART1 Tx (PA.09)为上拉推出 
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
   GPIO_Init(GPIOA, &GPIO_InitStructure);

   //配置串口：波特率、数据位、停止位、校验、流控制、模式
   USART_InitStructure.USART_BaudRate = BaudRate;
   USART_InitStructure.USART_WordLength = USART_WordLength_9b;
   USART_InitStructure.USART_StopBits = USART_StopBits_1;
   USART_InitStructure.USART_Parity = USART_Parity_Even;
   USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
   USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

   USART_Init(USART1, &USART_InitStructure);//配置串口1

   //使能串口接收中断
   USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
   //串口发送中断在发送数据时开启
   //USART_ITConfig(USART1, USART_IT_TXE, ENABLE);

   //使能 USART1
   USART_Cmd(USART1, ENABLE);

   //串口中断配置
   /* Configure the NVIC Preemption Priority Bits */  
   NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

   /* Enable the USART1 Interrupt */
   NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQChannel;
   NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
   NVIC_Init(&NVIC_InitStructure);
}