STM32F10XX中SPI的DMA发送数据

参考资料：

http://blog.csdn.net/jdh99/article/details/7603029

http://www.openedv.com/posts/list/3159.htm

    上面提到的两篇博文比较详细深刻的说明了DMA的工作方式以及SPI的DMA传输方式的特点。结合对Stm32F103VET6中SPI的DMA传输方式的配置和学习谈谈感受，在看下面的内容之前请先看上面的两篇参考博文，这里就不在说明。

    要使用SPI的DMA功能，首先配置好SPI外设，这里以SPI1为例子。下面的代码初始化了SPI1对应的GPIO以及SPI1工作的模式。

void SpiCC3000Init(void)

{

     SPI_InitTypeDef   SPI_InitStructure;

    GPIO_InitTypeDef  GPIO_InitStructure;

  /*!< Disable SPI */

  SPI_Cmd(SPI_USED, DISABLE);

  /*!< DeInitializes the SPI */

  SPI_I2S_DeInit(SPI_USED);

  /*!< SPI Periph clock disable */

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2 , DISABLE); 

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1 , DISABLE);   

/*Enable SPI2 Clock */

RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2,ENABLE);

  RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOB, ENABLE);

/*Enable SPI1 Clock */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1 |RCC_APB2Periph_GPIOA,ENABLE);

/*Config  SCLK and MOSI */

GPIO_InitStructure.GPIO_Pin = SPI_CLK_PIN| SPI_MOSI_PIN;// 

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//AF_PP

GPIO_Init(SPI_PORT, &GPIO_InitStructure);

  /*!< Configure SPI pins: MISO */

  GPIO_InitStructure.GPIO_Pin = SPI_MISO_PIN;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;

  GPIO_Init(SPI_PORT, &GPIO_InitStructure);

/*!< Configure SPI pins: CS output high */

GPIO_InitStructure.GPIO_Pin = SPI_CS_PIN;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;

GPIO_Init(SPI_PORT, &GPIO_InitStructure);

GPIO_SetBits(SPI_PORT,SPI_CS_PIN);

  /*!< CC3000 SPI Init */

  SPI_StructInit(&SPI_InitStructure);

  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_Low;  

  SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;

  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;

  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;/* The buadrate is a fraction of the 72MHz clock*/

  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;

SPI_InitStructure.SPI_CRCPolynomial = 7;

  SPI_Init(SPI_USED, &SPI_InitStructure);

  SPI_SSOutputCmd(SPI_USED,ENABLE);//NSS(CS) 

  SPI_Cmd(SPI_USED, ENABLE);

  /*Configure SPI for DMA Operation*/

#if defined(ENABLE_SPI_DMA)

  SpiCC3000DMAInit(); 

#else

  SpiRxInterruptClkInit();

#endif

}

    在配置好SPI1以后，配置DMA1功能（选择SPI1的Tx连接到DMA上），因为SPI1对应的DMA功能由DMA1来实现。  下面函数中的DMA时钟将在调用它的函数中开启。

void C3000_DMA_Config(SPI_DMADirection_TypeDef Direction, uint8_t* buffer, uint16_t NumData)

{

#if defined(ENABLE_SPI_DMA)

  DMA_InitTypeDef DMA_InitStructure;

  /* Initialize the DMA_PeripheralBaseAddr member */

  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t )&SPI1->DR; //SPI_DR_BASE; // 

//DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t )&SPI2->DR; //SPI_DR_BASE; // 

  /* Initialize the DMA_MemoryBaseAddr member */

  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)buffer;

   /* Initialize the DMA_PeripheralInc member */

  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

  /* Initialize the DMA_MemoryInc member */

  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

  /* Initialize the DMA_PeripheralDataSize member */

  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;

  /* Initialize the DMA_MemoryDataSize member */

  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;

  /* Initialize the DMA_Mode member */

//yichuan

  DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;

//DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

  /* Initialize the DMA_Priority member */

  DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;

  /* Initialize the DMA_M2M member */

  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

  /* If using DMA for Reception */

  if (Direction == SPI_DMA_RX)

  {

    /* Initialize the DMA_DIR member */

    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

    /* Initialize the DMA_BufferSize member */

    DMA_InitStructure.DMA_BufferSize = NumData;

    DMA_DeInit(SPI_DMA_RX_CHANNEL);

    DMA_Init(SPI_DMA_RX_CHANNEL, &DMA_InitStructure);

  }

   /* If using DMA for Transmission */

  else if (Direction == SPI_DMA_TX)

  { 

    /* Initialize the DMA_DIR member */

    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;

    /* Initialize the DMA_BufferSize member */

    DMA_InitStructure.DMA_BufferSize = NumData;

    DMA_DeInit(SPI_DMA_TX_CHANNEL);

    DMA_Init(SPI_DMA_TX_CHANNEL, &DMA_InitStructure);

  }

#endif

}

   配置好DMA1和SPI1后，要做的事情就是把二者联合起来，且配置DMA1的发送完成中断。

void SpiCC3000DMAInit(void)

{ 

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); 

  DMA_DeInit(SPI_DMA_RX_CHANNEL);

  DMA_DeInit(SPI_DMA_TX_CHANNEL);

  /* Configure and enable SPI DMA TX Channel interrupt */ 

 // NVIC_RxInt_InitStructure.NVIC_IRQChannel = DMA1_Channel5_IRQn; //SPI2 TX

  NVIC_RxInt_InitStructure.NVIC_IRQChannel = DMA1_Channel3_IRQn;//SPI1 TX // not config the Rx channel

  NVIC_RxInt_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

  NVIC_RxInt_InitStructure.NVIC_IRQChannelSubPriority = 0;//0

  NVIC_RxInt_InitStructure.NVIC_IRQChannelCmd = ENABLE;

  NVIC_Init(&NVIC_RxInt_InitStructure);

  /* Configure DMA Peripheral but don't send data*/

  C3000_DMA_Config(SPI_DMA_RX, (uint8_t*)wlan_rx_buffer,0); 

 //C3000_DMA_Config(SPI_DMA_TX, (uint8_t*)wlan_tx_buffer,0);

  C3000_DMA_Config(SPI_DMA_TX, (uint8_t*)wlan_tx_buffer,1700);  //buffer is 1700

    /* Enable SPI DMA request */

  SPI_I2S_DMACmd(SPI_USED,SPI_I2S_DMAReq_Tx, ENABLE);

  SPI_I2S_DMACmd(SPI_USED,SPI_I2S_DMAReq_Rx, ENABLE);

  /* Enable the DMA Channels Interrupts */

  /*It should be put after the DMA config  */

  DMA_ITConfig(SPI_DMA_TX_CHANNEL, DMA_IT_TC, ENABLE); 

  /* Enable DMA RX Channel */

  DMA_Cmd(SPI_DMA_RX_CHANNEL, ENABLE);  

/*Note: Enable the SPI_DMA Channel,it begin SPI translate*/

  /* Enable DMA TX Channel ,begin the dma translate*/  

  DMA_Cmd(SPI_DMA_TX_CHANNEL, ENABLE); 

}

  这里要强调的是：使能DMA中断标志的语句DMA_ITConfig(SPI_DMA_TX_CHANNEL, DMA_IT_TC, ENABLE); 应当放到DMA1配置完以后，不然发送数据完成以后，不会进入中断处理函数，就是相当于发送完成后产生中断的这个功能并没有配置成功，如果放到DMA1配置前面。下面的图片是参考手册中关于DMA的配置过程，其中中断的使能在第六步，所以应当在DMA初始化完成后，再使能中断功能。

    接下来就是中断处理函数了，响应传输完成中断的产生

void DMA1_Channel3_IRQHandler(void)

{

    if(DMA_GetITStatus(DMA1_IT_TC3)==SET)

    {

GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC,ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;

GPIO_Init(GPIOC, &GPIO_InitStructure);

GPIO_ResetBits(GPIOC,GPIO_Pin_6);

    }

   DMA_ClearITPendingBit(DMA1_IT_TC3);

}

最后启动DMA传输是通过DMA_Cmd(SPI_DMA_TX_CHANNEL, ENABLE) 这句话实现，当DMA通道被使能以后，它就自动开始传输数据，而不影响CPU其干其它事情，直到DMA传输完数据产生中断时，CPU才会去处理中断函数。