I2C integration using DMA Driver

[Piyoosh]

Hi All,

I am integrating the IMU sensor Using I2C DMA in circular mode on stm32f103c8t6 using Hal Library, so facing an issue reading the address value.

In the below code "HAL_I2C_STATE_READY " this flag is not resetting after once function executes so in 2nd execution this HAL_StatusTypeDef HAL_I2C_Mem_Read_DMA(I2C_HandleTypeDef *hi2c, uint16_t DevAddress, uint16_t MemAddress, uint16_t MemAddSize, uint8_t *pData, uint16_t Size) function is not trigering to DMA Handler function. 

if (hi2c->State == HAL_I2C_STATE_READY)
  {
    /* Wait until BUSY flag is reset */
    count = I2C_TIMEOUT_BUSY_FLAG * (SystemCoreClock / 25U / 1000U);
    do
    {
      count--;
      if (count == 0U)
      {
        hi2c->PreviousState       = I2C_STATE_NONE;
        hi2c->State               = HAL_I2C_STATE_READY;
        hi2c->Mode                = HAL_I2C_MODE_NONE;
        hi2c->ErrorCode           |= HAL_I2C_ERROR_TIMEOUT;

        return HAL_BUSY;
      }
    }
    while (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_BUSY) != RESET);

    /* Process Locked */
    __HAL_LOCK(hi2c);

    /* Check if the I2C is already enabled */
    if ((hi2c->Instance->CR1 & I2C_CR1_PE) != I2C_CR1_PE)
    {
      /* Enable I2C peripheral */
      __HAL_I2C_ENABLE(hi2c);
    }

    /* Disable Pos */
    CLEAR_BIT(hi2c->Instance->CR1, I2C_CR1_POS);

    hi2c->State     = HAL_I2C_STATE_BUSY_RX;
    hi2c->Mode      = HAL_I2C_MODE_MEM;
    hi2c->ErrorCode = HAL_I2C_ERROR_NONE;

    /* Prepare transfer parameters */
    hi2c->pBuffPtr    = pData;
    hi2c->XferCount   = Size;
    hi2c->XferSize    = hi2c->XferCount;
    hi2c->XferOptions = I2C_NO_OPTION_FRAME;
    hi2c->Devaddress  = DevAddress;
    hi2c->Memaddress  = MemAddress;
    hi2c->MemaddSize  = MemAddSize;
    hi2c->EventCount  = 0U;

    /* Enable Acknowledge */
    SET_BIT(hi2c->Instance->CR1, I2C_CR1_ACK);

    /* Generate Start */
    SET_BIT(hi2c->Instance->CR1, I2C_CR1_START);

    /* Process Unlocked */
    __HAL_UNLOCK(hi2c);

    if (hi2c->XferSize > 0U)
    {
      /* Note : The I2C interrupts must be enabled after unlocking current process
      to avoid the risk of I2C interrupt handle execution before current
      process unlock */

      /* Enable EVT, BUF and ERR interrupt */
      __HAL_I2C_ENABLE_IT(hi2c, I2C_IT_EVT | I2C_IT_BUF | I2C_IT_ERR);
    }
    return HAL_OK;
  }

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[TDK]

How are you calling the HAL functions and what you're expecting to happen?

[Saket_Om]

Hello @Piyoosh 

The HAL_I2C_STATE_READY flag is not reset immediately after the execution of HAL_I2C_Mem_Read_DMA(). Instead, the state remains busy until the transfer is complete. The end of the transfer is indicated by the invocation of the HAL_I2C_MemRxCpltCallback() function. To ensure that a subsequent transfer can be initiated successfully, you can either call the next transfer within the callback function or set a flag within this function and check it in the main loop before initiating the second transfer.

Please refer to the implementation in the code snippet below:

volatile uint8_t transferCompleteFlag = 0;

void HAL_I2C_MemRxCpltCallback(I2C_HandleTypeDef *hi2c) {
    // Set the flag to indicate the transfer is complete
    transferCompleteFlag = 1;
}

void I2C_Read_DMA(uint16_t DevAddress, uint16_t MemAddress, uint8_t *pData, uint16_t Size) {
    // Start the I2C memory read using DMA
    if (HAL_I2C_Mem_Read_DMA(&hi2c1, DevAddress, MemAddress, I2C_MEMADD_SIZE_8BIT, pData, Size) != HAL_OK) {
        // Handle error
    }
}

int main(void) {
    // HAL initialization
    HAL_Init();
    // System clock configuration
    SystemClock_Config();
    // I2C initialization
    MX_I2C1_Init();

    uint8_t data[10];
    uint16_t deviceAddress = 0x50;
    uint16_t memoryAddress = 0x00;

    // First I2C read transfer
    I2C_Read_DMA(deviceAddress, memoryAddress, data, sizeof(data));

    // Wait for the first transfer to complete
    while (transferCompleteFlag == 0) {
        // Optionally, you can add a timeout mechanism here
    }

    // Reset the flag for the next transfer
    transferCompleteFlag = 0;

    // Second I2C read transfer
    I2C_Read_DMA(deviceAddress, memoryAddress + 10, data, sizeof(data));

    // Main loop
    while (1) {
        // Application code
    }
}

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