初始化代码如下

void  init_spi_slave(void)
{
    spi_parameter_struct spi_init_struct;
    //打开spi口GPIO的时钟
rcu_periph_clock_enable(RCU_GPIOA);
   
    //打开spi口外设的时钟
    rcu_periph_clock_enable(clk_spi_slave);
   
    //Configure SPI_SLAVE pins: NSS, SCK and MOSI
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_10MHZ, GPIO_Pin_5);
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_10MHZ, GPIO_Pin_7);
    //cs
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_10MHZ, GPIO_Pin_4);
    //MISO
    gpio_init(GPIOA, GPIO_MODE_AF_PP,       GPIO_OSPEED_10MHZ, GPIO_Pin_6);
    spi_i2s_deinit(spi_slave);
    spi_struct_para_init(&spi_init_struct);
    spi_init_struct.trans_mode           = SPI_TRANSMODE_FULLDUPLEX;
    spi_init_struct.device_mode          = SPI_SLAVE;
    spi_init_struct.frame_size           = SPI_FRAMESIZE_8BIT;
    spi_init_struct.clock_polarity_phase = SPI_CK_PL_LOW_PH_2EDGE;
    spi_init_struct.nss                  = SPI_NSS_SOFT;
    spi_init_struct.prescale             = SPI_PSC_8;
    spi_init_struct.endian               = SPI_ENDIAN_MSB;
    spi_init(spi_slave, &spi_init_struct);
    spi_crc_off(spi_slave);
    spi_nss_internal_low(spi_slave);
    spi_enable(spi_slave);
}
void  spi_slave_rev_start(void)
{
    memset(link_rx, 0, 48);
    dma_memory_address_config(DMA0, DMA_CH1, (uint32_t)link_rx);
    dma_transfer_number_config(DMA0, DMA_CH1, link_rxbuf_len);
    dma_channel_enable(DMA0, DMA_CH1);
}
void  spi_slave_rev_stop(void)
{
    dma_transfer_number_config(DMA0, DMA_CH1, 0);
    dma_channel_disable(DMA0, DMA_CH1);
}
void  spi_slave_send_start(uint16_t  count)
{
    dma_memory_address_config(DMA0, DMA_CH2, (uint32_t)link_tx);
    dma_transfer_number_config(DMA0, DMA_CH2, count);
    dma_channel_enable(DMA0, DMA_CH2);
}
void  spi_slave_send_stop(void)
{
    dma_transfer_number_config(DMA0, DMA_CH2, 0);
    dma_channel_disable(DMA0, DMA_CH2);
}



void  init_spi_slave_dma(void)
{
    dma_parameter_struct dma_init_struct;
    rcu_periph_clock_enable(RCU_DMA0);
   
    dma_deinit(DMA0, DMA_CH1);
    dma_struct_para_init(&dma_init_struct);
   
    dma_init_struct.direction = DMA_PERIPHERAL_TO_MEMORY;
    dma_init_struct.memory_addr = (uint32_t)link_rx;
    dma_init_struct.memory_inc = DMA_MEMORY_INCREASE_ENABLE;
    dma_init_struct.memory_width = DMA_MEMORY_WIDTH_8BIT;
    dma_init_struct.number = link_rxbuf_len;
    dma_init_struct.periph_addr = (uint32_t)&SPI_DATA(spi_slave);
    dma_init_struct.periph_inc = DMA_PERIPH_INCREASE_DISABLE;
    dma_init_struct.periph_width = DMA_PERIPHERAL_WIDTH_8BIT;
    dma_init_struct.priority = DMA_PRIORITY_ULTRA_HIGH;
    dma_init(DMA0, DMA_CH1, &dma_init_struct);
    dma_circulation_disable(DMA0, DMA_CH1);
    dma_memory_to_memory_disable(DMA0, DMA_CH1);
    nvic_irq_enable(DMA0_Channel1_IRQn, 6, 0);
   
    dma_interrupt_enable(DMA0, DMA_CH1, DMA_INT_FTF);
    dma_interrupt_enable(DMA0, DMA_CH1, DMA_INT_ERR);
   
    dma_deinit(DMA0, DMA_CH2);
    dma_struct_para_init(&dma_init_struct);
   
    dma_init_struct.direction = DMA_MEMORY_TO_PERIPHERAL;
    dma_init_struct.memory_addr = (uint32_t)link_tx;
    dma_init_struct.memory_inc = DMA_MEMORY_INCREASE_ENABLE;
    dma_init_struct.memory_width = DMA_MEMORY_WIDTH_8BIT;
    dma_init_struct.number = link_txbuf_len;
    dma_init_struct.periph_addr = (uint32_t)&SPI_DATA(spi_slave);
    dma_init_struct.periph_inc = DMA_PERIPH_INCREASE_DISABLE;
    dma_init_struct.periph_width = DMA_PERIPHERAL_WIDTH_8BIT;
    dma_init_struct.priority = DMA_PRIORITY_ULTRA_HIGH;
    dma_init(DMA0, DMA_CH2, &dma_init_struct);
    dma_circulation_disable(DMA0, DMA_CH2);
    dma_memory_to_memory_disable(DMA0, DMA_CH2);
    nvic_irq_enable(DMA0_Channel2_IRQn, 6, 0);
   
    dma_interrupt_enable(DMA0, DMA_CH2, DMA_INT_FTF);
    dma_interrupt_enable(DMA0, DMA_CH2, DMA_INT_ERR);
    spi_dma_enable(spi_slave, SPI_DMA_TRANSMIT);
    spi_dma_enable(spi_slave, SPI_DMA_RECEIVE);
    slave_dma_send_stop();
}

而且从示波器里出来的MISO引脚波形比较奇怪。