目前这样测试：主机发数据给从机stm32时，从机stm32总回复0xa5. 但很多时候从机发的并不是0xa5,可能是其他数据。 例如主机可能收到以下错误的数据： 
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我使用示波器确认过从机发出的的确是这样的数据

1. #include "stm32f10x_lib.h"
   
   void spi_to_arm11_clock(void)
   {
        GPIO_InitTypeDef GPIO_InitStructure;
   
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
       RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
   
       /* Configure SPI2 pins: SCK, MISO and MOSI ---------------------------------*/
       GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
       GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
       GPIO_Init(GPIOB, &GPIO_InitStructure);
   }
   
   void spi_to_arm11_cfg(void)
   {
       SPI_InitTypeDef SPI_InitStructure;
   
       SPI_Cmd(SPI2, DISABLE);//必须先禁能,才能改变MODE
   
       SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
       SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
       SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
       SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
       SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
       SPI_InitStructure.SPI_Mode = SPI_Mode_Slave;
       SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
       SPI_InitStructure.SPI_CRCPolynomial = 7;
       SPI_Init(SPI2, &SPI_InitStructure);
   
       SPI_NSSInternalSoftwareConfig(SPI2, SPI_NSSInternalSoft_Reset);//设置内部NSS为低电平
   
       SPI_Cmd(SPI2, ENABLE);
   }
   
   int spi_to_arm11_read8(u8 * value)
   {
       if (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) != RESET)
       {
            *value = SPI_I2S_ReceiveData(SPI2);
           return 0;
       }
   
       return -1;
   }
   
   int spi_to_arm11_write8(u8 value)
   {
       while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
       SPI_I2S_SendData(SPI2, value);
       return 0;
   
       return -1;
   }
   
   int main()
   {
   ...............
   ...............
   while(1)
   spi_to_arm11_write8(0xa5);
   }

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