GPIO_PinAFConfig(SPI1_SCK_PORT,  SPI1_SCK_PIN_SRC,  SPI1_SCK_AF); // SCK
        GPIO_PinAFConfig(SPI1_MISO_PORT, SPI1_MISO_PIN_SRC, SPI1_MISO_AF); // MOSI
        GPIO_PinAFConfig(SPI1_MOSI_PORT, SPI1_MOSI_PIN_SRC, SPI1_MOSI_AF); // MISO

        RCC_AHB1PeriphClockCmd_safe(SPI1_CLK_GPIO_FN_PARAM, ENABLE);
        RCC_APB2PeriphClockCmd_safe(RCC_APB2Periph_SPI1, ENABLE);

        baud_prescaler = (clk.PCLK2_Frequency) / freq;

        gpio_init.GPIO_Mode  = GPIO_Mode_AF;
        gpio_init.GPIO_OType = GPIO_OType_PP;
        gpio_init.GPIO_PuPd  = GPIO_PuPd_NOPULL;

        if      (freq <=  2000000UL) gpio_init.GPIO_Speed = GPIO_Speed_2MHz;
        else if (freq <= 25000000UL) gpio_init.GPIO_Speed = GPIO_Speed_25MHz;
        else if (freq <= 50000000UL) gpio_init.GPIO_Speed = GPIO_Speed_50MHz;
        else                         gpio_init.GPIO_Speed = GPIO_Speed_100MHz;

        gpio_init.GPIO_Pin = (uint32_t)SPI1_SCK_PIN;
        GPIO_Init(SPI1_SCK_PORT, &gpio_init);
        gpio_init.GPIO_Pin = (uint32_t)SPI1_MOSI_PIN;
        GPIO_Init(SPI1_MOSI_PORT, &gpio_init);
        gpio_init.GPIO_Pin = (uint32_t)SPI1_MISO_PIN;
        GPIO_Init(SPI1_MISO_PORT, &gpio_init);

    if      (baud_prescaler <= 2)   SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
    else if (baud_prescaler <= 4)   SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;
    else if (baud_prescaler <= 8)   SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;
    else if (baud_prescaler <= 16)  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_16;
    else if (baud_prescaler <= 32)  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_32;
    else if (baud_prescaler <= 64)  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_64;
    else if (baud_prescaler <= 128) SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_128;
    else                            SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;

    SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
    SPI_InitStructure.SPI_Mode      = SPI_Mode_Master;
    SPI_InitStructure.SPI_DataSize  = SPI_DataSize_8b;
    SPI_InitStructure.SPI_CPOL      = cpol;
    SPI_InitStructure.SPI_CPHA      = cpha;

    SPI_InitStructure.SPI_NSS       = SPI_NSS_Soft;
    SPI_InitStructure.SPI_FirstBit  = SPI_FirstBit_MSB;

    SPI_Init(spi, &SPI_InitStructure);

    SPI_Cmd(spi, ENABLE);

            DMA_InitTypeDef dma_init;

            RCC_AHB1PeriphClockCmd_safe(dma_data->rx.rcc | dma_data->tx.rcc, ENABLE);

            DMA_DeInit(dma_tx_stream);
            DMA_DeInit(dma_rx_stream);

            dma_init.DMA_BufferSize         = 1;
            dma_init.DMA_PeripheralInc      = DMA_PeripheralInc_Disable;
            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_Medium;
            dma_init.DMA_FIFOMode           = DMA_FIFOMode_Disable;
            dma_init.DMA_FIFOThreshold      = DMA_FIFOThreshold_1QuarterFull;
            dma_init.DMA_MemoryBurst        = DMA_MemoryBurst_Single;
            dma_init.DMA_PeripheralBurst    = DMA_PeripheralBurst_Single;
            dma_init.DMA_PeripheralBaseAddr = (uint32_t)&spi->DR;
            dma_init.DMA_Memory0BaseAddr    = NULL;
            dma_init.DMA_MemoryInc          = DMA_MemoryInc_Disable;

            dma_init.DMA_Channel            = dma_data->tx.ch;
            dma_init.DMA_DIR                = DMA_DIR_MemoryToPeripheral;
            DMA_Init(dma_tx_stream, &dma_init);

            dma_init.DMA_Channel            = dma_data->rx.ch;
            dma_init.DMA_DIR                = DMA_DIR_PeripheralToMemory;
            DMA_Init(dma_rx_stream, &dma_init);

        if (rbuf != NULL)
        {
            dma_rx_stream->M0AR = (uint32_t)rbuf;
            dma_rx_stream->CR  |= DMA_MemoryInc_Enable;
        }
        else
        {
            dma_rx_stream->M0AR = (uint32_t)&dummy_buf;
            dma_rx_stream->CR  &= ~DMA_MemoryInc_Enable;
        }

        if (wbuf != NULL)
        {
            dma_tx_stream->M0AR = (uint32_t)wbuf;
            dma_tx_stream->CR  |= DMA_MemoryInc_Enable;
        }
        else
        {
            dma_tx_stream->M0AR = (uint32_t)&dummy_buf;
            dma_tx_stream->CR  &= ~DMA_MemoryInc_Enable;
        }

        dma_rx_stream->NDTR = cnt;
        dma_tx_stream->NDTR = cnt;

        DMA_ClearITPendingBit(dma_rx_stream, dma_data->rx.it_tcif);
        DMA_ClearITPendingBit(dma_tx_stream, dma_data->tx.it_tcif);
        DMA_ITConfig(dma_rx_stream, DMA_IT_TC, ENABLE);

        SPI_I2S_DMACmd(spi, SPI_I2S_DMAReq_Tx | SPI_I2S_DMAReq_Rx, ENABLE);
        DMA_Cmd(dma_rx_stream, ENABLE);
        DMA_Cmd(dma_tx_stream, ENABLE);