串口波特率的奇怪现象！（找到原因了）

发表于 2015-3-20 11:21

本帖最后由 yzzly 于 2015-3-21 13:33 编辑

103VET6芯片，产品已经生产快1年了，默认9600波特的速率也完全测试过，系统时钟为72M（通过MCO看到），当波特率设置较低（如2400和4800）基本正确，当设置9600及以上时实际输出就不对了（虽然MDK能够看到波特率为要设置的值），头大了！

发表于 2015-3-20 11:27

应该不至于出现这种情况吧。电路有没有问题呢

发表于 2015-3-20 12:17

程序哪里有问题吧；我用内部晶振，115200波特率都OK；

发表于 2015-3-20 17:22

要崩溃了！

发表于 2015-3-20 19:45

#define BaudRate 115200
void Uart2_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
//----开启Usart1和GPIOA的Rcc时钟,
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE); //开启USART1的Clk,
RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART2,ENABLE); //通过对应位设置使Usart1寄存器复位,
RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART2,DISABLE); //退出复位,
//初始化串口1,引脚Pa9,
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
//初始化串口1,引脚Pa10
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
//初始化串口1,
USART_InitStructure.USART_BaudRate = BaudRate; //波特率设置
USART_InitStructure.USART_WordLength = USART_WordLength_8b; //字长8bit,
USART_InitStructure.USART_StopBits = USART_StopBits_1; //停止位1,
USART_InitStructure.USART_Parity = USART_Parity_No; //奇偶校验无,CR1的PCE和PS位,
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; //流控制无,
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //收发都使能,
USART_Init(USART2, &USART_InitStructure);
//使能串口1,
USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
USART_Cmd(USART2, ENABLE);
}

发表于 2015-3-20 19:46

我的串口初始化程序，仅供参考；

发表于 2015-3-21 13:34

找到原因了，在完善程序的过程中CPU初始化顺序被本人调整过，奶奶的！

发表于 2015-3-21 14:16

本帖最后由 yzzly 于 2015-3-21 14:18 编辑

真不明白，这3条语句的顺序怎么影响串口的波特率？
ADC_Configuration();
TIMx_Configuration();
DMA_Configuration();

发表于 2015-3-23 10:33

如果把DMA_Configuration()放在前面发现不但是串口波特率不对，systick的定时周期都增加了近10%，谁给解释是为什么呢？void ConfigDMA1C2(void) //
{
DMA_InitTypeDef DMA_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1,ENABLE); //Ê¹ÄÜDMA1Ê±ÖÓ
DMA_DeInit(DMA1_Channel2);
if(DMA1_TCIE_C2)
{
NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel2_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&ADC12_Buf+AdcPrNum*AdcChNum/2*4; //Ä¿µÄ»º³åÇø
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)&ADC1_Buf; //Ô´»º³åÇø
DMA_InitStructure.DMA_BufferSize = AdcPrNum*AdcChNum/2; //´«ÊäÊýÁ¿

DMA_InitStructure.DMA_M2M = DMA1_MTOM_C2; //´æ´¢Æ÷µ½´æ´¢Æ÷Ä£Ê½
DMA_InitStructure.DMA_Priority = DMA1_PL_C2; //DMA1Í¨µÀÓÅÏÈ¼¶
DMA_InitStructure.DMA_MemoryDataSize = DMA1_MSIZE_C2; //´æ´¢Æ÷Êý¾Ý¿í¶È(Byte¡¢HarfWord¡¢Word)
DMA_InitStructure.DMA_PeripheralDataSize = DMA1_PSIZE_C2; //ÍâÉèÊý¾Ý¿í¶È(Byte¡¢HarfWord¡¢Word)
DMA_InitStructure.DMA_MemoryInc = DMA1_MINC_C2; //´æ´¢Æ÷µØÖ·ÔöÁ¿Ä£Ê½
DMA_InitStructure.DMA_PeripheralInc = DMA1_PINC_C2; //ÍâÉèµØÖ·ÔöÁ¿Ä£Ê½
DMA_InitStructure.DMA_Mode = DMA1_CIRC_C2; //DMA1Ñ»·Ä£Ê½
DMA_InitStructure.DMA_DIR = DMA1_DIR_C2; //Êý¾Ý´«Êä·½Ïò

DMA_Init(DMA1_Channel2, &DMA_InitStructure);

DMA_ITConfig(DMA1_Channel2, DMA_IT_TC , ENABLE); //Ê¹ÄÜDMA1Í¨µÀ2´«ÊäÍê³ÉÖÐ¶Ï

DMA_Cmd(DMA1_Channel2, ENABLE); //Ê¹ÄÜDMA1Í¨µÀ2
}

void ConfigDMA2C1(void)
{
DMA_InitTypeDef DMA_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2,ENABLE); //Ê¹ÄÜDMA2Ê±ÖÓ
DMA_DeInit(DMA2_Channel1);
if(DMA2_TCIE_C1)
{
NVIC_InitStructure.NVIC_IRQChannel = DMA2_Channel1_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&ADC12_Buf; //Ä¿µÄ»º³åÇø
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)&ADC12_Buf+AdcPrNum*AdcChNum/2*4; //Ô´»º³åÇø
DMA_InitStructure.DMA_BufferSize = AdcPrNum*AdcChNum/2; //´«ÊäÊýÁ¿

DMA_InitStructure.DMA_M2M = DMA2_MTOM_C1; //´æ´¢Æ÷µ½´æ´¢Æ÷Ä£Ê½
DMA_InitStructure.DMA_Priority = DMA2_PL_C1; //DMA2Í¨µÀÓÅÏÈ¼¶
DMA_InitStructure.DMA_MemoryDataSize = DMA2_MSIZE_C1; //´æ´¢Æ÷Êý¾Ý¿í¶È(Byte¡¢HarfWord¡¢Word)
DMA_InitStructure.DMA_PeripheralDataSize = DMA2_PSIZE_C1; //ÍâÉèÊý¾Ý¿í¶È(Byte¡¢HarfWord¡¢Word)
DMA_InitStructure.DMA_MemoryInc = DMA2_MINC_C1; //´æ´¢Æ÷µØÖ·ÔöÁ¿Ä£Ê½
DMA_InitStructure.DMA_PeripheralInc = DMA2_PINC_C1; //ÍâÉèµØÖ·ÔöÁ¿Ä£Ê½
DMA_InitStructure.DMA_Mode = DMA2_CIRC_C1; //DMA2Ñ»·Ä£Ê½
DMA_InitStructure.DMA_DIR = DMA2_DIR_C1; //Êý¾Ý´«Êä·½Ïò

DMA_Init(DMA2_Channel1, &DMA_InitStructure);

DMA_ITConfig(DMA2_Channel1, DMA_IT_TC , ENABLE); //Ê¹ÄÜDMA2Í¨µÀ1´«ÊäÍê³ÉÖÐ¶Ï

DMA_Cmd(DMA2_Channel1, ENABLE); //Ê¹ÄÜDMA2Í¨µÀ1
}

发表于 2015-3-23 10:38

把DMA的中断优先级改低试试

发表于 2015-3-23 10:48

本系统是定时器定时启动ADC转换，ADC1及ADC2各有5个输入通道。每周期（20毫秒）每个通道转换32次，ADC1每次转换结束DMA1的C1读走，DMA1的C1与C2每10毫秒中断一次。

[STM32F1] 串口波特率的奇怪现象！（找到原因了）

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