LED Port configuration with STM32H573I-DK (PushPull vs. OpenDrain)

[OliverScheid]

When configuring the LEDs for the STM32H573I-DK using the STM32CubeMX it generated code which initializes the LED pins as PushPull (rather than OpenDrain).

Lookign at the schematics of the STM32H573I-DK it seems to be not "the best option".

Would you agree that OpenDrain (GPIO_MODE_OUTPUT_OD) is the better option here, rather than PushPull (GPIO_MODE_OUTPUT_PP)?

/**
  * @brief  Configures LED on GPIO.
  * @PAram  Led LED to be configured.
  *          This parameter can be one of the following values:
  *            @arg  LED1
  *            @arg  LED2
  *            @arg  LED3
  *            @arg  LED4
  * @retval BSP status
  */
int32_t BSP_LED_Init(Led_TypeDef Led)
{
  int32_t ret = BSP_ERROR_NONE;
  GPIO_InitTypeDef  gpio_init_structure;

  if ((Led != LED1) && (Led != LED2) && (Led != LED3) && (Led != LED4))
  {
    ret = BSP_ERROR_WRONG_PARAM;
  }
  else
  {
    switch (Led)
    {
      case LED2:
        /* Enable the LED2 GPIO clock */
        LED2_GPIO_CLK_ENABLE();
        break;
      case LED3:
        /* Enable the LED3 GPIO clock */
        LED3_GPIO_CLK_ENABLE();
        break;
      case LED4:
        /* Enable the LED4 GPIO clock */
        LED4_GPIO_CLK_ENABLE();
        break;
      case LED1:
      default:
        /* Enable the LED1 GPIO clock */
        LED1_GPIO_CLK_ENABLE();
        break;
    }
    /* Configure the GPIO_LED pin */
    gpio_init_structure.Mode = GPIO_MODE_OUTPUT_PP;
    gpio_init_structure.Pull = GPIO_NOPULL;
    gpio_init_structure.Speed = GPIO_SPEED_FREQ_HIGH;
    gpio_init_structure.Pin = LED_PIN [Led];
    HAL_GPIO_Init(LED_PORT[Led], &gpio_init_structure);
    HAL_GPIO_WritePin(LED_PORT [Led], (uint16_t)LED_PIN[Led], GPIO_PIN_SET);
  }

  return ret;
}

 

[Andrew Neil]

Both would work.

OD is all that's needed, but push-pull would not hurt.

[OliverScheid]

For clarification: The tool generates push-pull.

I am saying it should create open-drain, instead.

[Andrew Neil]

Moved to the CubeMX forum then.

But the generated code is perfectly fine - no problem in using push-pull.

PS:

There are cases where not all GPIOs support open-drain - so maybe it's just taking the most general case?

[OliverScheid · Accepted solution]

Well, "perfectly fine" is not what I would call it. Because I assume that the 3V3 supply of the LEDs is (slightly) higher than what the STM32H5 drives on the PF4/PF1/PI8/PI9. So, even if LEDs are OFF, you will have a small (useless) current flow.

But if you don't care about current consumption, then, of course, you are perfectly fine ;)