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SPI continuous transmfer problems

Question asked by shine on Mar 17, 2014
Latest reply on Mar 17, 2014 by francescato.diego
dear sir, 
I use the STM32F4 uP to control peripheral IC by SPI protocol.
And I composed the source code according to the the reference manual (Doc ID 018909 Rev 5). However, the data is invalid after SPI_I2S_FLAG_RXNE asserted. The data is valid after more than 1us. 
By a scope, the peripheral IC sends the data correctly. 

It seem not accordant with the the figure as the following. 

SPI_master.png

Would you help me to figure out how to access the SPI correctly? 

Best Regards 
Shine Hou 

attached information 
Device: STM32F407IG
IDE: KeilC 
source code: 
1. SPI initialization 
{
  GPIO_InitTypeDef GPIO_InitStruct;
  SPI_InitTypeDef  SPI_InitStruct;
  // NVIC_InitTypeDef NVIC_InitStruct;  


  /* Peripheral Clock Enable -------------------------------------------------*/
  /* Enable the SPI clock (Port B) */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);  
  
  /* Enable GPIO clocks (Port B) */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE); 


  /* SPI GPIO Configuration --------------------------------------------------*/
  /* GPIO Deinitialisation */
  GPIO_DeInit(GPIOB);
  
  /* Connect SPI (SCK & MISO & MOSI) pins to AF5 */  
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_SPI2); // SPI2_SCK
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource14, GPIO_AF_SPI2); // SPI2_MISO
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, GPIO_AF_SPI2); // SPI2_MOSI
  
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStruct.GPIO_PuPd  = GPIO_PuPd_DOWN;
  
  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_Init(GPIOB, &GPIO_InitStruct);
  
  /* SPI CS1 pin configuration */
  GPIO_InitStruct.GPIO_Pin = SPI_CS_PIN; 
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOB, &GPIO_InitStruct);
  
  GPIO_SetBits(GPIOB, GPIO_InitStruct.GPIO_Pin ); 


 
  /* SPI configuration -------------------------------------------------------*/
  /* SPI Deinitialisation */
  SPI_I2S_DeInit(SPI2);
  
  SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
  SPI_InitStruct.SPI_DataSize = SPI_DataSize_8b;
  SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;
  SPI_InitStruct.SPI_CPHA = SPI_CPHA_2Edge;
  SPI_InitStruct.SPI_NSS = SPI_NSS_Soft;
  SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;
  SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStruct.SPI_CRCPolynomial = 7;
  
  SPI_InitStruct.SPI_Mode = SPI_Mode_Master; // Master Mode
  SPI_Init(SPI2, &SPI_InitStruct);
  
  SPI_Cmd(SPI2, ENABLE);


}

2. SPI Read 
          GPIO_ResetBits(GPIOB, SPI_CS_PIN);             
          while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
          SPI_I2S_SendData(SPI2, reg_addr | 0x80);          
         
          for (n1=0; n1<reg_num; n1++ )
          {
            while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
            SPI_I2S_SendData(SPI2, 0x00);                        
            while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);          
            reg_rdata[n1] = SPI_I2S_ReceiveData(SPI2);
          }
          GPIO_SetBits(GPIOB, SPI_CS_PIN);             

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