找到原因了
PA15默认不是普通IO口，要remap一下，此贴终结。。。。 没仔细看PA15定义。。。
多谢大家

两条数据线加10k上拉试试

尝试直接拉高 MISO 对应的管脚，逻辑分析仪抓到的还是低电平

/*!
    \file    main.c
    \brief   SPI fullduplex communication use polling mode

    \version 2017-02-10, V1.0.0, firmware for GD32F30x
    \version 2018-10-10, V1.1.0, firmware for GD32F30x
    \version 2018-12-25, V2.0.0, firmware for GD32F30x
    \version 2020-09-30, V2.1.0, firmware for GD32F30x
*/

/*
    Copyright (c) 2020, GigaDevice Semiconductor Inc.

    Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this
       list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.
    3. Neither the name of the copyright holder nor the names of its contributors
       may be used to endorse or promote products derived from this software without
       specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
OF SUCH DAMAGE.
*/

#include "gd32f30x.h"
#include "gd32f307c_eval.h"

#define arraysize         10
#define SET_SPI0_NSS_HIGH          gpio_bit_set(GPIOA,GPIO_PIN_4);
#define SET_SPI0_NSS_LOW           gpio_bit_reset(GPIOA,GPIO_PIN_4);

#define SET_SPI2_NSS_HIGH          gpio_bit_set(GPIOA,GPIO_PIN_15);
#define SET_SPI2_NSS_LOW           gpio_bit_reset(GPIOA,GPIO_PIN_15);

uint32_t send_n = 0, receive_n = 0;
uint8_t spi0_send_array[arraysize] = {0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA};
uint8_t spi2_send_array[arraysize] = {0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA};
uint8_t spi0_receive_array[arraysize];
uint8_t spi2_receive_array[arraysize];
ErrStatus memory_compare(uint8_t* src, uint8_t* dst, uint8_t length);

void rcu_config(void);
void gpio_config(void);
void spi_config(void);

/*!
    \brief      main function
    \param[in]  none
    \param[out] none
    \retval     none
*/
int main(void)
{
    /* init led2 and led3 */
    gd_eval_led_init(LED2);
    gd_eval_led_init(LED3);
    /* peripheral clock enable */
    rcu_config();
    /* GPIO config */
    gpio_config();
    /* SPI config */
    spi_config();

    SET_SPI0_NSS_HIGH

    /* SPI enable */
    spi_enable(SPI2);
    spi_enable(SPI0);

    SET_SPI0_NSS_LOW

    /* wait for transmit complete */
    while(send_n < arraysize){
        while(RESET == spi_i2s_flag_get(SPI2, SPI_FLAG_TBE));
        spi_i2s_data_transmit(SPI2, 'A');//spi2_send_array[send_n]);
        while(RESET == spi_i2s_flag_get(SPI0, SPI_FLAG_TBE));
        spi_i2s_data_transmit(SPI0, spi0_send_array[send_n++]);
        while(RESET == spi_i2s_flag_get(SPI2, SPI_FLAG_RBNE));
        spi2_receive_array[receive_n] = spi_i2s_data_receive(SPI2);
        while(RESET == spi_i2s_flag_get(SPI0, SPI_FLAG_RBNE));
        spi0_receive_array[receive_n++] = spi_i2s_data_receive(SPI0);
    }

    SET_SPI0_NSS_HIGH

    /* compare receive data with send data */
    if(memory_compare(spi2_receive_array, spi0_send_array, arraysize))
        gd_eval_led_on(LED2);
    else
        gd_eval_led_off(LED2);

    if(memory_compare(spi0_receive_array, spi2_send_array, arraysize))
        gd_eval_led_on(LED3);
    else
        gd_eval_led_off(LED3);

    while(1);
}

/*!
    \brief      configure different peripheral clocks
    \param[in]  none
    \param[out] none
    \retval     none
*/
void rcu_config(void)
{
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_GPIOB);
    rcu_periph_clock_enable(RCU_SPI0);
    rcu_periph_clock_enable(RCU_SPI2);
    rcu_periph_clock_enable(RCU_AF);
}

/*!
    \brief      configure the GPIO peripheral
    \param[in]  none
    \param[out] none
    \retval     none
*/
void gpio_config(void)
{
    /* SPI0 GPIO config:SCK/PA5, MISO/PA6, MOSI/PA7 */
    gpio_init(GPIOA, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_5 | GPIO_PIN_7);
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_6);
    /* PA3 as NSS */
    gpio_init(GPIOA, GPIO_MODE_OUT_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_4);
   
    /* SPI2 GPIO config: NSS/PA4, SCK/PC10, MISO/PC11, MOSI/PC12 */
    gpio_init(GPIOB, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_3 | GPIO_PIN_5);
    gpio_init(GPIOB, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_4);
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_15);
}

void gpio_config0(void)
{
    /* SPI0 GPIO config:SCK/PA5, MISO/PA6, MOSI/PA7 */
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_5 | GPIO_PIN_7);
    gpio_init(GPIOA, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_6);
    /* PA3 as NSS */
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_4);
   
    /* SPI2 GPIO config: NSS/PA4, SCK/PC10, MISO/PC11, MOSI/PC12 */
    gpio_init(GPIOB, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_3 | GPIO_PIN_5);
    gpio_init(GPIOB, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_50MHZ, GPIO_PIN_4);
    gpio_init(GPIOA, GPIO_MODE_OUT_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_15);
}

/*!
    \brief      configure the SPI peripheral
    \param[in]  none
    \param[out] none
    \retval     none
*/
void spi_config0(void)
{
    spi_parameter_struct spi_init_struct;

    /* SPI0 parameter config */
    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_1EDGE;
    spi_init_struct.nss                  = SPI_NSS_HARD;
    spi_init_struct.prescale             = SPI_PSC_256;
    spi_init_struct.endian               = SPI_ENDIAN_MSB;
    spi_init(SPI0, &spi_init_struct);

    /* SPI2 parameter config */
    spi_init_struct.device_mode = SPI_MASTER;
    spi_init_struct.nss         = SPI_NSS_SOFT;
    spi_init(SPI2, &spi_init_struct);
}

void spi_config(void)
{
    spi_parameter_struct spi_init_struct;

    /* SPI0 parameter config */
    spi_init_struct.trans_mode           = SPI_TRANSMODE_FULLDUPLEX;
    spi_init_struct.device_mode          = SPI_MASTER;
    spi_init_struct.frame_size           = SPI_FRAMESIZE_8BIT;
    spi_init_struct.clock_polarity_phase = SPI_CK_PL_LOW_PH_1EDGE;
    spi_init_struct.nss                  = SPI_NSS_SOFT;
    spi_init_struct.prescale             = SPI_PSC_256;
    spi_init_struct.endian               = SPI_ENDIAN_MSB;
    spi_init(SPI0, &spi_init_struct);

    /* SPI2 parameter config */
    spi_init_struct.device_mode = SPI_SLAVE;
    spi_init_struct.nss         = SPI_NSS_HARD;
    spi_init(SPI2, &spi_init_struct);
}

/*!
    \brief      memory compare function
    \param[in]  src: source data pointer
    \param[in]  dst: destination data pointer
    \param[in]  length: the compare data length
    \param[out] none
    \retval     ErrStatus: ERROR or SUCCESS
*/
ErrStatus memory_compare(uint8_t* src, uint8_t* dst, uint8_t length)
{
    while (length--){
        if (*src++ != *dst++)
            return ERROR;
    }
    return SUCCESS;
}

从机就没发出来

还有一种方法验证，用IO模拟SPI，看收发是否正常，之后再检查上面一步

这种情况还是需要抓取一下从机数据是否发送，有个SPI的使用技巧，从机的时钟也是主机给的，你在读取从机的数据的时候需要先随意发送一个数据给时钟信号，你可以检查一下只读数据是无法读到的

那检查一下从机的SPI代码是否有问题，用示波器看一下从机的数据输出IO有没有信号就知道了。