【求助】STM32F103 SPI1的NSS管脚影响DAC通道1的输出

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361119128 提问时间：2014-11-4 16:25 /

不启用SPI1时，DAC通道1输出声音信号正常，没有噪音。启用 SPI1读写外部器件的时候，DAC输出声音有很大的噪音。
CPU型号:STM32F103CBT6

赞收藏评论5 发布时间：2014-11-4 16:25

5个回答

361119128 回答时间：2014-11-4 16:26:26

SPI1配置如下：
  SPI_InitTypeDef  SPI_InitStructure;
  GPIO_InitTypeDef  GPIO_InitStructure;
  RCC_APB2PeriphClockCmd(  RCC_APB2Periph_AFIO |RCC_APB2Periph_SPI1|RCC_APB2Periph_GPIOB , ENABLE);    //时钟允许

/* Configure SPI1 pins: NSS, SCK, MISO and MOSI */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //Flash 管脚
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_12 ;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //Flash 管脚
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

  SPI_FLASH_CS_HIGH();
  /* SPI1 configuration */
  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 = SPI_CPOL_High;
  SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(SPI1, &SPI_InitStructure);

  SPI_Cmd(SPI1, ENABLE);

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