一个关于spi驱动外设的问题。

只看该作者 · 2015-4-14 16:18

我现在要用stm32驱动一个adc(ad5310),要把cs拉低，clk发送时钟，data发生数据，数据在clk的上升沿取样（原本是下降沿，现在在adc的clk前加了一个反相器），一共要发送16位数据，现在用I/O来模拟不行，用spi模块也不行，为什么？下面是我写的驱动程序，有人能看出问题出在哪里吗？
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1,ENABLE);
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE,ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5|GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //spi_clk  spi_mosi
  GPIO_Init(GPIOA,&GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_12;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;    //spi_cs
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOE, &GPIO_InitStructure);

  SPI_InitStructure.SPI_Direction = SPI_Direction_1Line_Tx;
  SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
  SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
  SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
  SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft; //SPI_NSS_Hard
  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(SPI1,&SPI_InitStructure);

  // SPI1 enable
  SPI_Cmd(SPI1,ENABLE);

   GPIO_ResetBits  (GPIOE, GPIO_Pin_12);
  SpiDelay(10);
      while(SPI_I2S_GetFlagStatus(SPI1,SPI_I2S_FLAG_TXE)==RESET);
SPI_WriteByte(0x0f);
   while(SPI_I2S_GetFlagStatus(SPI1,SPI_I2S_FLAG_TXE)==RESET);
            SPI_WriteByte(0xff);
      SpiDelay(10);
GPIO_SetBits  (GPIOE, GPIO_Pin_12);