STM32 serial port reception uses DMA double buffering

#define IMAGE_BUFFER_SIZE 100 //In words After testing, increasing this value did not improve the speed

u32 Image_Buffer1[IMAGE_BUFFER_SIZE]={0};
u32 Image_Buffer2[IMAGE_BUFFER_SIZE]={0};

//OV2640 JPEG mode interface configuration
void OV2640_JpegDcmiInit(void)
{
DCMI_InitTypeDef DCMI_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure; //NVIC
/*** Configures the DCMI to interface with the OV2640 camera module ***/
/* Enable DCMI clock */
RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_DCMI, ENABLE);

/* DCMI configuration */ 
DCMI_InitStructure.DCMI_CaptureMode = DCMI_CaptureMode_Continuous; // Single DCMI_CaptureMode_Continuous;
DCMI_InitStructure.DCMI_SynchroMode = DCMI_SynchroMode_Hardware;
DCMI_InitStructure.DCMI_PCKPolarity = DCMI_PCKPolarity_Rising; //
DCMI_InitStructure.DCMI_VSPolarity = DCMI _VSPolarity_Low;
DCMI_InitStructure.DCMI_HSPolarity = DCMI_HSPolarity_Low;
DCMI_InitStructure.DCMI_CaptureRate = DCMI_CaptureRate_All_Frame;
DCMI_InitStructure.DCMI_ExtendedDataMode = DCMI_ExtendedDataMode_8b;
//Initialize DCMI
DCMI_Init(&DCMI_InitStructure);
//Enable J PG
DCMI_JPEGCmd(ENABLE);

/* Configures the DMA2 to transfer Data from DCMI */
/* Enable DMA2 clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);

/* DMA2 Stream1 Configuration */  
DMA_DeInit(DMA2_Stream1);

DMA_InitStructure.DMA_Channel = DMA_Channel_1; InitStructure.DMA_PeripheralBaseAddr  
= DCMI_DR_ADDRESS; 
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&Image_Buffer1;//Transfer to internal array
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = IMAGE_BUFFER_SIZE; //以字为单位
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//使能增长模式
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;//DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
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;
/*DMA double buffer mode*///Double buffer mode
DMA_DoubleBufferModeConfig(DMA2_Stream1,(uint32_t)&Image_Buffer2,DMA_Memory_0);//DMA_Memory_0 is transferred first
DMA_DoubleBufferModeCmd(DMA2_Stream1,ENABLE);
DMA_Init(DMA2_Stream1, &DMA_InitStructure); //Initialize DMA

Dma_FreeBuf_Ok = 0;//No data is ready at this time
// DMA_Cmd(DMA2_Stream1,ENABLE);//Start DMA2_Stream1

//Interrupt enable
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
NVIC_InitStructure.NVIC_IRQChannel = DCMI_IRQn; 
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; 
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; 
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; 
NVIC_Init(&NVIC_InitStructure); 
DCMI_ITConfig(DCMI_IT_FRAME,ENABLE); //Interrupt enable

NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 4;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
DMA_ITConfig(DMA2_Stream1,DMA_IT_TC,ENABLE);
}

//DMA transfer completed interrupt
void DMA2_Stream1_IRQHandler(void)
{
DMA_InitTypeDef DMA_InitStructure;
if(DMA_GetITStatus(DMA2_Stream1,DMA_IT_TCIF1) != RESET)
{
DMA_ClearITPendingBit(DMA2_Stream1,DMA_IT_TCIF1);
Dma_FreeBuf_Ok = 1;//There is data ready
}
}


//Main loop
while(1)
{
//uip_polling();
if(Dma_FreeBuf_Ok == 1)//DMA has a free buffer
{
usart_sendJPEGdata();
Dma_FreeBuf_Ok = 0;
}


//Serial port transmission
void usart_sendJPEGdata(void)
{
u32 i;
if(DMA_GetCurrentMemoryTarget(DMA2_Stream1) == 1)
{
for(i=0;i{
USART_SendData(USART2,Image_Buffer1);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
USART_SendData(USART2,Image_Buffer1>>8);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
USART_SendData(USART2,I mage_Buffer1>>16);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
USART_SendData(USART2,Image_Buffer1>>24);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
}
}
else
{
for(i=0;i{
USART_SendData(USART2, Image_Buffer2);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
USART_SendData(USART2,Image_Buffer2>>8);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
USART_SendData(USART2,Image_Buffer2>>16);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET);
USART_SendData(USART2,Image_Buffer2>>24);
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET); 
}
}
}