title: stm32 DMA cannot send data to SPI1 DR (Cannot use DMA to send data to SPI)
body: <p>I am trying to use DMA to send data to SPI1. SPI1 will then control DAC for voltage update. </p>
  
  <p>The chip used is STM32F407. Therefore, the corresponding channel/stream is： channel3/stream5, as is shown in reference manual. However, when the DMA is enabled, no data is shown in SPI1->DR and there are no results shown in the oscilloscope. </p>
  
  <p>The SPI works fine when SPI1->DR is written by software. Could anyone help to check out what has happened? Here comes the code:</p>
  
  <pre><code>uint16_t DACData[1]; 
  void InitDMA(void)
  {
      DMA_InitTypeDef DMA_InitStructure;
      DMA_Cmd(DMA2_Stream2, DISABLE);
      while (DMA2_Stream2-&gt;CR &amp; DMA_SxCR_EN);
      //SPI1 Tx DMA
      DMA_DeInit(DMA2_Stream5);
      DMA_StructInit(&amp;DMA_InitStructure);
      RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE); //Init DMA clock
      DMA_InitStructure.DMA_Channel = DMA_Channel_3;//SPI1 Tx 
      DMA_InitStructure.DMA_PeripheralBaseAddr  = (uint32_t)&amp;(SPI1-&gt;DR); //Set the SPI1 Tx
      DMA_InitStructure.DMA_Memory0BaseAddr  = (uint32_t)&amp;DACData;       //Set the memory location
      DMA_InitStructure.DMA_DIR  = DMA_DIR_MemoryToPeripheral;           //
      DMA_InitStructure.DMA_BufferSize  = 1;            //Define the number of bytes to send
      DMA_InitStructure.DMA_PeripheralInc  = DMA_PeripheralInc_Disable;             
      DMA_InitStructure.DMA_MemoryInc  = DMA_MemoryInc_Disable;            
      DMA_InitStructure.DMA_PeripheralDataSize  = DMA_PeripheralDataSize_HalfWord;    
      DMA_InitStructure.DMA_MemoryDataSize  = DMA_PeripheralDataSize_HalfWord;        
      DMA_InitStructure.DMA_Mode  = DMA_Mode_Normal;               //Normal mode (not circular)
      DMA_InitStructure.DMA_Priority  = DMA_Priority_High;                
      DMA_InitStructure.DMA_FIFOMode  = DMA_FIFOMode_Disable;  //Operate in 'direct mode' 
      DMA_InitStructure.DMA_MemoryBurst =DMA_MemoryBurst_Single;
      DMA_InitStructure.DMA_PeripheralBurst =DMA_PeripheralBurst_Single;
      DMA_Init(DMA2_Stream5, &amp;DMA_InitStructure); //DMA2, Channel 3, stream 5
  
      //Enable the transfer complete interrupt for DMA2 Stream5
      DMA_ITConfig(DMA2_Stream5, DMA_IT_TC, ENABLE);                                       
  }
  </code></pre>
  
  <p>Here is how SPI1 initialized</p>
  
  <pre><code>void InitSPI1(void) 
   {
      GPIO_InitTypeDef GPIO_InitStruct;
      SPI_InitTypeDef SPI_InitStruct;
      // enable clock for used IO pins
      RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
      GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;
      GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
      GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
      GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
      GPIO_Init(GPIOA, &amp;GPIO_InitStruct);
  
      // connect SPI1 pins to SPI alternate function
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1); //SCK
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1); //MISO
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1); //MOSI
      // enable peripheral clock
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
  
      /* configure SPI1 in Mode 0 
       * CPOL = 0 --&gt; clock is low when idle
       * CPHA = 0 --&gt; data is sampled at the first edge
       */
      SPI_InitStruct.SPI_Direction = SPI_Direction_1Line_Tx; // one line transmission
      SPI_InitStruct.SPI_Mode = SPI_Mode_Master;     // transmit in master mode, NSS pin has to be always high
      SPI_InitStruct.SPI_DataSize = SPI_DataSize_16b; // one packet of data is 16 bits wide
      SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;        // clock is low when idle
      SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge
      SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set;; // set the NSS management to hardware
      SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256; // SPI frequency is APB2 frequency / 4 = 21MHz
      SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first
  
      SPI_Init(SPI1, &amp;SPI_InitStruct); 
      SPI_Cmd(SPI1, ENABLE); // enable SPI1
  }
  </code></pre>
  
  <p>I try to use these commands to start DMA:</p>
  
  <pre><code>DACData[0]=0xff00;
  DMA_Cmd(DMA2_Stream5, ENABLE);
  </code></pre>
  
  <p>In case it may help, here comes the register values for DMA2, Stream 5
  <img src="https://i.stack.imgur.com/CmfOG.jpg" alt="enter image description here">
  <img src="https://i.stack.imgur.com/RJxI8.jpg" alt="enter image description here"></p>