AnsweredAssumed Answered

SPI Rx data reading error

Question asked by kim.andy on May 15, 2013
Latest reply on May 16, 2013 by kim.andy
Hello,

I code the SPI IF to read/write a data to a slave device.
But the master(STM32) does not have a valid data in DR of SPI.

The code for receiving a data is like following.

uint8_t SPI_rx_data(void)
{
 uint8_t data;

 /* Tx a dummy data */
 while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
 SPI_I2S_SendData(SPI1, data);

 /* Wait for SPI1 data reception */
 while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
 data = SPI_I2S_ReceiveData(SPI1);
 
 return data;
}

I could find a data(0xff or 0x80) from the slave according to SCK  when tranmit a dummy data.
But the master(STM32) does not have a valid data(0xff or 0x80) in the DR of SPI.
It has always 0x00 data.

So I have checked the following code, example code of SPI.
Also the DR of SPI has always 0x00 data.

int main(void)
{
  /*!< At this stage the microcontroller clock setting is already configured,
       this is done through SystemInit() function which is called from startup
       file (startup_stm32f10x_xx.s) before to branch to application main.
       To reconfigure the default setting of SystemInit() function, refer to
       system_stm32f10x.c file
     */    
      
  /* System clocks configuration ---------------------------------------------*/
  RCC_Configuration();

  /* GPIO configuration ------------------------------------------------------*/
  GPIO_Configuration();

  /* SPI1 configuration ------------------------------------------------------*/
  SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
  SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
  SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b;
  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;
  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(SPI1, &SPI_InitStructure);

  /* SPI2 configuration ------------------------------------------------------*/
  SPI_InitStructure.SPI_Mode = SPI_Mode_Slave;
  SPI_Init(SPI2, &SPI_InitStructure);

  /* Enable SPI1 CRC calculation */
  SPI_CalculateCRC(SPI1, ENABLE);
  /* Enable SPI2 CRC calculation */
  SPI_CalculateCRC(SPI2, ENABLE);

  /* Enable SPI1 */
  SPI_Cmd(SPI1, ENABLE);
  /* Enable SPI2 */
  SPI_Cmd(SPI2, ENABLE);

  /* Transfer procedure */
  while (TxIdx < BufferSize - 1)
  {
    /* Wait for SPI1 Tx buffer empty */
    while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
    /* Send SPI2 data */
    SPI_I2S_SendData(SPI2, SPI2_Buffer_Tx[TxIdx]);
    /* Send SPI1 data */
    SPI_I2S_SendData(SPI1, SPI1_Buffer_Tx[TxIdx++]);
    /* Wait for SPI2 data reception */
    while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
    /* Read SPI2 received data */
    SPI2_Buffer_Rx[RxIdx] = SPI_I2S_ReceiveData(SPI2);
    /* Wait for SPI1 data reception */
    while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
    /* Read SPI1 received data */
    SPI1_Buffer_Rx[RxIdx++] = SPI_I2S_ReceiveData(SPI1);
  }

  /* Wait for SPI1 Tx buffer empty */
  while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
  /* Wait for SPI2 Tx buffer empty */
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);

  /* Send last SPI2_Buffer_Tx data */
  SPI_I2S_SendData(SPI2, SPI2_Buffer_Tx[TxIdx]);
  /* Enable SPI2 CRC transmission */
  SPI_TransmitCRC(SPI2);
  /* Send last SPI1_Buffer_Tx data */
  SPI_I2S_SendData(SPI1, SPI1_Buffer_Tx[TxIdx]);
  /* Enable SPI1 CRC transmission */
  SPI_TransmitCRC(SPI1);

  /* Wait for SPI1 last data reception */
  while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
  /* Read SPI1 last received data */
  SPI1_Buffer_Rx[RxIdx] = SPI_I2S_ReceiveData(SPI1);

  /* Wait for SPI2 last data reception */
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
  /* Read SPI2 last received data */
  SPI2_Buffer_Rx[RxIdx] = SPI_I2S_ReceiveData(SPI2);

  /* Wait for SPI1 data reception: CRC transmitted by SPI2 */
  while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
  /* Wait for SPI2 data reception: CRC transmitted by SPI1 */
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);

  /* Check the received data with the send ones */
  TransferStatus1 = Buffercmp(SPI2_Buffer_Rx, SPI1_Buffer_Tx, BufferSize);
  TransferStatus2 = Buffercmp(SPI1_Buffer_Rx, SPI2_Buffer_Tx, BufferSize);
  /* TransferStatus1, TransferStatus2 = PASSED, if the data transmitted and received
     are correct */
  /* TransferStatus1, TransferStatus2 = FAILED, if the data transmitted and received
     are different */

  /* Test on the SPI1 CRC Error flag */
  if ((SPI_I2S_GetFlagStatus(SPI1, SPI_FLAG_CRCERR)) == SET)
  {
    TransferStatus2 = FAILED;
  }

  /* Test on the SPI2 CRC Error flag */
  if ((SPI_I2S_GetFlagStatus(SPI2, SPI_FLAG_CRCERR)) == SET)
  {
    TransferStatus1 = FAILED;
  }

  /* Read SPI1 received CRC value */
  CRC1Value = SPI_I2S_ReceiveData(SPI1);
  /* Read SPI2 received CRC value */
  CRC2Value = SPI_I2S_ReceiveData(SPI2);

  while (1)
  {}
}

/**
  * @brief  Configures the different system clocks.
  * @param  None
  * @retval None
  */
void RCC_Configuration(void)
{
  /* PCLK2 = HCLK/2 */
  RCC_PCLK2Config(RCC_HCLK_Div2);

  /* Enable peripheral clocks --------------------------------------------------*/
  /* GPIOA, GPIOB and SPI1 clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB |
                         RCC_APB2Periph_SPI1, ENABLE);

  /* SPI2 Periph clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
}

/**
  * @brief  Configures the different GPIO ports.
  * @param  None
  * @retval None
  */
void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  /* Configure SPI1 pins: SCK, MISO and MOSI ---------------------------------*/
  /* Confugure SCK and MOSI pins as Alternate Function Push Pull */
  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;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  /* Confugure MISO pin as Input Floating  */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
 
  /* Configure SPI2 pins: SCK, MISO and MOSI ---------------------------------*/
  /* Confugure SCK and MOSI pins as Input Floating */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOB, &GPIO_InitStructure);
  /* Confugure MISO pin as Alternate Function Push Pull */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOB, &GPIO_InitStructure);
 
}

Why the DR of SPI has always 0x00 data ?
Are there any problem in these codes ?

Thanks 

Outcomes