STM32 的Usart1数据发送 DMA方式的疑问：

hkys_lxh

DMA发送经过测试是好的，但是DMA接收有问题，一个字节是对的，2个以上字节就第一个是对的，其他错，请高手帮忙看一下程序：
注：
//#define BUF_SIZE 500 
//
中断优先级初始化如下：

void InterruptInit(void)

{

NVIC_InitTypeDef   NVIC_InitStructure;

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);

NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

}

串口初始化程序如下：

void UART_Init(void)

{

GPIO_InitTypeDef   GPIO_InitStructure;

USART_InitTypeDef  USART_InitStructure;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;//USART1 引脚初始化

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;//上拉输入

GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//复用推挽输出

GPIO_Init(GPIOA, &GPIO_InitStructure);

USART_InitStructure.USART_BaudRate = 9600;

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);

USART_Cmd(USART1,ENABLE);

USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);

USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE);

USART1_RX;

}
//DMA发送

void USART1_SendData(uint8_t *data,uint16_t length)

{

DMA_InitTypeDef    DMA_InitStructure;

USART1_TX;

DMA_DeInit(DMA1_Channel4);

DMA_InitStructure.DMA_PeripheralBaseAddr =(uint32_t)(&USART1->DR); //设置外设地址

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)data;    //设置存储器地址

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;    //外设作为数据传输目的地

DMA_InitStructure.DMA_BufferSize = length;    //设置DMA通道缓存大小

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;  //外设地址寄存器地址不变

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;   //内存地址寄存器地址递增

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;

DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;     //工作在正常缓存模式

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; //非内存到内存传输

DMA_Init(DMA1_Channel4, &DMA_InitStructure);

DMA_ITConfig(DMA1_Channel4,DMA_IT_TC,ENABLE);

USART_DMACmd(USART1,USART_DMAReq_Tx,ENABLE);

DMA_Cmd(DMA1_Channel4,ENABLE);

}

//串口DMA发送中断函数：

void DMA1_Channel4_IRQHandler(void)

{

if(DMA_GetITStatus(DMA1_IT_TC4)==SET)

{

DMA_ClearITPendingBit(DMA1_IT_TC4);

USART_ClearITPendingBit(USART1,USART_IT_TC);//波特率较低时需要这一句

USART_ITConfig(USART1,USART_IT_TC,ENABLE);

}

}
//串口1中断处理函数

void USART1_IRQHandler(void)

{

DMA_InitTypeDef    DMA_InitStructure;

uint32_t tmp=0;//无意义，仅用于清除IDLE标志位，由软件序列清除该位(先读USART_SR，然后读USART_DR)

if(USART_GetITStatus(USART1,USART_IT_RXNE)==SET) //收到第一个字节后开DMA，关接收中断，开空闲中断

{

USART_ClearITPendingBit(USART1,USART_IT_RXNE);

USART_ITConfig(USART1,USART_IT_RXNE,DISABLE);

USART_ITConfig(USART1,USART_IT_IDLE,ENABLE);

DMA_DeInit(DMA1_Channel5);

DMA_InitStructure.DMA_PeripheralBaseAddr =(uint32_t)(&USART1->DR);

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&ModBusData.RxBuf[0];

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

DMA_InitStructure.DMA_BufferSize =BUF_SIZE-1;//

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_Normal;

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_Init(DMA1_Channel5, &DMA_InitStructure);

DMA_Cmd(DMA1_Channel5,ENABLE);

}

else if(USART_GetITStatus(USART1,USART_IT_IDLE)==SET) //收到最后一个字节后清除空闲标志，取数据，关DMA，开接收中断，关空闲中断

{

tmp|=USART1->SR;//先读USART_SR

tmp|=USART1->DR;//然后读USART_DR

{

ModBusData.PackLen=BUF_SIZE-1-DMA_GetCurrDataCounter(DMA1_Channel5);//ModBusData.PackLen   

DMA_Cmd(DMA1_Channel5,DISABLE);

USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);

USART_ITConfig(USART1,USART_IT_IDLE,DISABLE);

if(ModBusData.PackLen>3)      //串口发送大于3，就置位接收结束标志，把ModBusData.PackLen>3改成ModBusData.PackLen>0，只能接收一个是对的，大于一个就不对了

get_a_pack=0x01;

}

}

else if(USART_GetITStatus(USART1,USART_IT_TC)==SET)//最后一个数据发送完以后，置成接收状态

{

USART_ClearITPendingBit(USART1,USART_IT_TC);

USART_ITConfig(USART1,USART_IT_TC,DISABLE);

USART1_RX;

}

}
主程序：

int main(void)

{

init_stm32();

TaskInit();

while (1)

{

    if(get_a_pack == 1)

    {

       USART1_SendData (&ModBusData.RxBuf[0],ModBusData.PackLen);//将接收到的数据再发出去，送到上位机

      get_a_pack=0;//接收接收标志清零

    }

}