DAC out doesn't work properly on STM32H562ZI

[MattiaB]

Good morning everyone,
I need to drive an external pump using DAC out pheriperal.

I am working with an STM32H562ZI microcontroller and have followed the guide available at the following link: Getting started with DAC

Below is my current configuration:

/**
  * @brief DAC1 Initialization Function
  * @param None
  * @retval None
  */
static void MX_DAC1_Init(void)
{

  /* USER CODE BEGIN DAC1_Init 0 */

  /* USER CODE END DAC1_Init 0 */

  DAC_ChannelConfTypeDef sConfig = {0};

  /* USER CODE BEGIN DAC1_Init 1 */

  /* USER CODE END DAC1_Init 1 */

  /** DAC Initialization
  */
  hdac1.Instance = DAC1;
  if (HAL_DAC_Init(&hdac1) != HAL_OK)
  {
    Error_Handler();
  }

  /** DAC channel OUT1 config
  */
  sConfig.DAC_HighFrequency = DAC_HIGH_FREQUENCY_INTERFACE_MODE_ABOVE_80MHZ;
  sConfig.DAC_DMADoubleDataMode = DISABLE;
  sConfig.DAC_SignedFormat = DISABLE;
  sConfig.DAC_SampleAndHold = DAC_SAMPLEANDHOLD_DISABLE;
  sConfig.DAC_Trigger = DAC_TRIGGER_NONE;
  sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
  sConfig.DAC_ConnectOnChipPeripheral = DAC_CHIPCONNECT_EXTERNAL;
  sConfig.DAC_UserTrimming = DAC_TRIMMING_FACTORY;
  if (HAL_DAC_ConfigChannel(&hdac1, &sConfig, DAC_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN DAC1_Init 2 */

  /* USER CODE END DAC1_Init 2 */

}

After that, I implemented the following example and expected to obtain a stepped waveform. However, the result is not as expected: the DAC seems to skip some steps, producing an irregular curve as shown in the image below:

#include <stdbool.h>

bool setRaw(uint16_t value_raw)
{
    while(HAL_DAC_STATE_READY != HAL_DAC_GetState(&hdac1));
    while((hdac1.Instance->SR & DAC_SR_DAC1RDY) == 0x00);

    do {

      HAL_DAC_SetValue(&hdac1, DAC_CHANNEL_1, DAC_ALIGN_12B_R,
                                         value_raw);

    } while(HAL_DAC_GetValue(&hdac1, DAC_CHANNEL_1) != value_raw);

    return true;
}
/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DAC1_Init();

  /* USER CODE BEGIN 2 */
  HAL_DAC_Start(&hdac1, DAC_CHANNEL_1);
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  uint32_t timeBetweenVariation = 100;

  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
    HAL_Delay(timeBetweenVariation);
    setRaw(0);

    HAL_Delay(timeBetweenVariation);
    setRaw(1000);

    HAL_Delay(timeBetweenVariation);
    setRaw(2000);

    HAL_Delay(timeBetweenVariation);
    setRaw(3000);

    HAL_Delay(timeBetweenVariation);
    setRaw(4095);
  }
  /* USER CODE END 3 */
}

setRaw method performs other checks before doing HAL_DAC_SetValue. By performing the HAL_DAC_SetValue call directly doesn’t change. 

On the other hand, when I run the provided example code, the generated waveform is correct:

strange steps curve

using the example code insted seems the generated curve is correct:
 

example triangular curve

 

Could you please help me understand what I might be missing?

Thank you in advance,
Mattia

[Andrew Neil]

using the example code insted seems the generated curve is correct

So look at how your code differs from the example code … ?

[MattiaB]

Changing only the main function it works.

The only difference is that I change every 100 ms the value and the values are not contigues each other (1000, 2000, ecc..).

The example perform a step of one unit (0,1,2, ecc...) every millisecond.

HAL_DAC_SetValue(&hdac1, DAC_CHANNEL_2, DAC_ALIGN_12B_R, dac_value);
if (dac_value < 4095) {
	dac_value++;
} else {
	dac_value=0;
}
HAL_Delay(1);

 

So why my solution cannot work?

[Andrew Neil]

No, that’s not the only difference!

 

You do all this:

    while(HAL_DAC_STATE_READY != HAL_DAC_GetState(&hdac1));
    while((hdac1.Instance->SR & DAC_SR_DAC1RDY) == 0x00);

    do {
      HAL_DAC_SetValue( &hdac1, DAC_CHANNEL_1, DAC_ALIGN_12B_R, value_raw );
    } while(HAL_DAC_GetValue(&hdac1, DAC_CHANNEL_1) != value_raw);

The example simply does HAL_DAC_SetValue

 

BTW: what’s the point of the return value from setRaw - it’s always true !?

[mƎALLEm]

Hello,

Look at the DAC examples provided in the H5 Cube HAL package:

https://github.com/STMicroelectronics/STM32CubeH5/tree/main/Projects/NUCLEO-H563ZI/Examples/DAC

 

[MattiaB]

Connecting the DAC pheriperal to a TIMER trigger the DAC start to work properly:
 

sConfig.DAC_Trigger = DAC_TRIGGER_T1_TRGO;