DMA双缓存串口发数据有乱码

ftmcu · 发表于 2016-12-22 16:24:57

我用的是原子F407开发板，我的DMA双缓存配置如下

   DMA_InitTypeDef  DMA_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
if((u32)DMA_Streamx>(u32)DMA2)
{
   RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2,ENABLE);

}else
{
   RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1,ENABLE);
}
  DMA_DeInit(DMA_Streamx);

while (DMA_GetCmdStatus(DMA_Streamx) != DISABLE){}

  DMA_InitStructure.DMA_Channel = chx;
  DMA_InitStructure.DMA_PeripheralBaseAddr = par;
  DMA_InitStructure.DMA_Memory0BaseAddr = mar0;
  DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
  DMA_InitStructure.DMA_BufferSize = ndtr;
  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_Circular;
  DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;
  DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
  DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull;
  DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
  DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
  DMA_Init(DMA_Streamx, &DMA_InitStructure);

/*DMA double buffer mode*///
DMA_DoubleBufferModeConfig(DMA_Streamx,(uint32_t)&mar1,DMA_Memory_0);
DMA_DoubleBufferModeCmd(DMA_Streamx,ENABLE);

发送的双缓存为和发送的数据数量为
#define SEND_BUF_SIZE 8

u8 SendBuff[]={0x01,0x02,0x03,0x04};
u8 SendBuff1[]={0x09,0x0a,0x0b,0x0c};

我在主函数中

                  while(1)
   {
if(DMA_GetFlagStatus(DMA2_Stream7,DMA_FLAG_TCIF7)!=RESET)
{
DMA_ClearFlag(DMA2_Stream7,DMA_FLAG_TCIF7);
break;
}

}
现象：
1：当我使能DMA传输时
      MYDMA_Enable(DMA2_Stream7,SEND_BUF_SIZE);
   串口不停的循环收到
   01 02 03 04 09 0A 0B 0C 10 00 00 00 08 00 00 00
   应该只收到01 02 03 04 09 0A 0B 0C才对呀
   为什么会有10 00 00 00 08 00 00 00这些数据呀？
2：当我在传输完成时关掉DMA也就是只传一次的时候
if(DMA_GetFlagStatus(DMA2_Stream7,DMA_FLAG_TCIF7)!=RESET)
{

                           MYDMA_Disable(DMA2_Stream7);
                           DMA_ClearFlag(DMA2_Stream7,DMA_FLAG_TCIF7);
break;
}
数据是正确的，即01 02 03 04 09 0A 0B 0C没有乱码。

求助：拜托各位大神指点下，怎么循环发送，没有乱码。谢谢啦！