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I'm trying to enable or disable two DAC outputs of STM32F407 board. STM32CubeMX tools shows the following options:

enter image description here

Above I choose both output buffers as Enable.

And the auto generated code is as follows:

static void MX_DAC_Init(void)
{

  /* USER CODE BEGIN DAC_Init 0 */

  /* USER CODE END DAC_Init 0 */

  DAC_ChannelConfTypeDef sConfig = {0};

  /* USER CODE BEGIN DAC_Init 1 */

  /* USER CODE END DAC_Init 1 */
  /** DAC Initialization
  */
  hdac.Instance = DAC;
  if (HAL_DAC_Init(&hdac) != HAL_OK)
  {
    Error_Handler();
  }
  /** DAC channel OUT1 config
  */
  sConfig.DAC_Trigger = DAC_TRIGGER_NONE;
  sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
  if (HAL_DAC_ConfigChannel(&hdac, &sConfig, DAC_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  /** DAC channel OUT2 config
  */
  if (HAL_DAC_ConfigChannel(&hdac, &sConfig, DAC_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN DAC_Init 2 */

  /* USER CODE END DAC_Init 2 */

}

And in this HAL document, it says:

enter image description here

My question is in the generated code there is no separate codes for DAC1 and DAC2. There is only:

sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;

How come one line of code sets both DAC output buffer types?

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  • 2
    \$\begingroup\$ The line of code you're looking at is only loading values into the sConfig struct. That same struct is then used in HAL_DAC_ConfigChannel for both DAC_CHANNEL_1 and DAc_CHANNEL_2. Just look at the comments in the code which CUBE_MX generated for you... \$\endgroup\$
    – brhans
    Feb 28 at 13:00

1 Answer 1

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It's only a matter of how the code is written.

The structure sConfig is created once, and used twice when calling HAL_DAC_ConfigChannel(), once for each channel. Since both channels have the same settings, this works fine.

If the two channels had different settings, sConfig would have been modified between the two usages.

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