FAQs
cancel
Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for 
Search instead for 
Did you mean: 

STM32 discovery board SPI receive

gmali9
Associate

‎2015-05-26 11:50 AM

Posted on May 26, 2015 at 20:50

Intro

I am using the STM32 Discovery board to talk with sensor that receives and sends data packet on SPI1. I have unpopulated U5 on the discovery board so that it lets me use the SPI1 port. I can send the data packet (3 bytes of data accompanied by 2 bytes of modbusCRC16 checksum. The sensor receives the packet ok and sends data back in a similar packet.

On implementing the checksum I found that none of the packets that i received were matching. On probing(literally) with a scope I found that the data on the scope did not match the memory (using KeilMDK debugger)

Issue

Last bit on certain bytes is carried or borrowed i.e. in a packet where the scope shows 04h, 00h,00h,30h,01h the memory shows 05h, 00h,00h,30h, 00h and is fairly consistent, another example is Scope : F0h,00h,00h,71h,F3h Memory: F1h,00h,00h,70h,F3h

I know that there is a dummy byte that comes as zero when first read, however, i do not understand this. Kindly advise.

spi.c

void MX_SPI1_Init(void)

{

  hspi1.Instance = SPI1;

  hspi1.Init.Mode = SPI_MODE_MASTER;

  hspi1.Init.Direction = SPI_DIRECTION_2LINES;

  hspi1.Init.DataSize = SPI_DATASIZE_8BIT;

  hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;

  hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;

  hspi1.Init.NSS = SPI_NSS_HARD_OUTPUT;

//  hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256;

    hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_64;

  hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;

  hspi1.Init.TIMode = SPI_TIMODE_DISABLED;

  hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLED;

  HAL_SPI_Init(&hspi1);

}

void HAL_SPI_MspInit(SPI_HandleTypeDef* hspi)

{

  GPIO_InitTypeDef GPIO_InitStruct;

  if(hspi->Instance==SPI1)

  {

  /* USER CODE BEGIN SPI1_MspInit 0 */

  /* USER CODE END SPI1_MspInit 0 */

    /* Peripheral clock enable */

    __SPI1_CLK_ENABLE();

 

    /**SPI1 GPIO Configuration    

    PA5     ------> SPI1_SCK

    PA6     ------> SPI1_MISO

    PA7     ------> SPI1_MOSI

    PA15     ------> SPI1_NSS

    */

    GPIO_InitStruct.Pin = GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_15;

    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

    GPIO_InitStruct.Pull = GPIO_NOPULL;

    GPIO_InitStruct.Speed = GPIO_SPEED_LOW;

    GPIO_InitStruct.Alternate = GPIO_AF5_SPI1;

    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /* USER CODE BEGIN SPI1_MspInit 1 */

  /* USER CODE END SPI1_MspInit 1 */

  }

}

void HAL_SPI_MspDeInit(SPI_HandleTypeDef* hspi)

{

  if(hspi->Instance==SPI1)

  {

  /* USER CODE BEGIN SPI1_MspDeInit 0 */

  /* USER CODE END SPI1_MspDeInit 0 */

    /* Peripheral clock disable */

    __SPI1_CLK_DISABLE();

 

    /**SPI1 GPIO Configuration    

    PA5     ------> SPI1_SCK

    PA6     ------> SPI1_MISO

    PA7     ------> SPI1_MOSI

    PA15     ------> SPI1_NSS

    */

    HAL_GPIO_DeInit(GPIOA, GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_15);

  /* USER CODE BEGIN SPI1_MspDeInit 1 */

  /* USER CODE END SPI1_MspDeInit 1 */

  }

}

/* USER CODE BEGIN 1 */

void HAL_SPI_enable(SPI_HandleTypeDef *hspi)

{

        if((hspi->Instance->CR1 &SPI_CR1_SPE) != SPI_CR1_SPE)

        {

      /* Enable SPI peripheral */

      __HAL_SPI_ENABLE(hspi);

        }

}

uint8_t HAL_SPI_TxRx1Byte(SPI_HandleTypeDef *hspi, uint8_t TxData)

{

        uint8_t RxData;

        static uint8_t firstEntryFlag = 0;

    /* Process Locked */

    __HAL_LOCK(hspi);

    /* Check if the SPI is not enabled */

    if((hspi->Instance->CR1 &SPI_CR1_SPE) != SPI_CR1_SPE)

    {

      /* Enable SPI peripheral */

      __HAL_SPI_ENABLE(hspi);

    }

        hspi->Instance->DR = TxData;

        while (!SPI_FLAG_RXNE);

        RxData = hspi->Instance->DR;

        __HAL_UNLOCK(hspi);

        

        return RxData;

}

Preview file
11 KB
0 Kudos
1 REPLY 1
Top