SPI的DMA模式初始化代码

以下是SPI的DMA模式初始化代码，供参考：

// 假设SPI1的时钟已经开启
// 假设DMA1的时钟已经开启

// 初始化SPI1
SPI_InitTypeDef spi_init;
spi_init.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
spi_init.SPI_Mode = SPI_Mode_Master;
spi_init.SPI_DataSize = SPI_DataSize_8b;
spi_init.SPI_CPOL = SPI_CPOL_Low;
spi_init.SPI_CPHA = SPI_CPHA_1Edge;
spi_init.SPI_NSS = SPI_NSS_Soft;
spi_init.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
spi_init.SPI_FirstBit = SPI_FirstBit_MSB;
spi_init.SPI_CRCPolynomial = 7;
SPI_Init(SPI1, &spi_init);
SPI_Cmd(SPI1, ENABLE);

// 初始化DMA1的通道2
DMA_InitTypeDef dma_init;
dma_init.DMA_DIR = DMA_DIR_PeripheralToMemory;
dma_init.DMA_BufferSize = 32;
dma_init.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
dma_init.DMA_MemoryInc = DMA_MemoryInc_Enable;
dma_init.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
dma_init.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
dma_init.DMA_Mode = DMA_Mode_Normal;
dma_init.DMA_Priority = DMA_Priority_High;
dma_init.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel2, &dma_init);

// 配置DMA1的通道2，使其从SPI1的数据寄存器中读取数据
DMA_Cmd(DMA1_Channel2, DISABLE);
DMA_DeInit(DMA1_Channel2);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(SPI1->DR);
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)rx_buffer;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = 32;
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_Channel2, &DMA_InitStructure);

// 配置SPI1的DMA接收模式
SPI_I2S_DMACmd(SPI1, SPI_I2S_DMAReq_Rx, ENABLE);

// 启动DMA1的通道2
DMA_Cmd(DMA1_Channel2, ENABLE);

以上代码中，使用了DMA1的通道2作为SPI1的DMA接收通道。其中，rx_buffer是一个接收数据的缓冲区，大小为32字节。在实际使用时，需要根据具体的应用场景进行修改。