我在使用SPI时，总是出现OVR标志。有谁碰到过这种情况吧，下面是部分代码：
//------------------SPI 初始化部分----------------
/* 1st phase: SPI1 Master and SPI2 Slave */
/* SPI1 Config -------------------------------------------------------------*/
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_LSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_Init(SPI1, &SPI_InitStructure);
/* Enable SPI1 */
SPI_Cmd(SPI1, ENABLE);
//实际工作部分，我直接连接了SPI1的MISO和MOSI引脚，实现SPI1的自环测试
GPIO_ResetBits(GPIOB,GPIO_Pin_15); //对外的cs选择，暂时无效了
/* Wait for SPI1 Tx buffer empty */
while(SPI_GetFlagStatus(SPI1, SPI_FLAG_TXE)==RESET);
//发送数据
SPI_SendData(SPI1,0x81);
//接收并丢弃收到的数据
if(SPI_GetFlagStatus(SPI1,SPI_FLAG_RXNE) == SET)
SPI_ReceiveData(SPI1);
while(SPI_GetFlagStatus(SPI1, SPI_FLAG_TXE)==RESET);
SPI_SendData(SPI1,0x00); //一旦发送完毕，就出现SPI_FLAG_OVR标志，
if(SPI_GetFlagStatus(SPI1,SPI_FLAG_RXNE) == SET)
SPI_ReceiveData(SPI1);
while(SPI_GetFlagStatus(SPI1, SPI_FLAG_TXE)==RESET);
SPI_SendData(SPI1,0x3C);
GPIO_SetBits(GPIOB,GPIO_Pin_15);
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