Configuration register SYSCFG_PMCR set wrong value when config pins like PC3_C as GPIO

[xiaosiyu0603]

Describe the set-up

• Board: Custom board
• Chip: STM32H735IGK6 (UFBGA176+25)
• IDE: CubeMX 6.92 + MPU Package for H7 Series 1.11.1 + Keil MDK-ARM 5.36 + ArmClang 6.16

Describe the bug

Due to the board layout constraints, I have to utilize PC3_C as PC3 for GPIO function (since PC3 is not in use). This design is supported by the chip.

Therefore, I configured PC3_C as a GPIO pin using CubeMX --

Subsequently, I generated the code using CubeMX --

void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOG_CLK_ENABLE();
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();
  __HAL_RCC_GPIOF_CLK_ENABLE();
  __HAL_RCC_GPIOH_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
// config other pins ...

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_3, GPIO_PIN_RESET);

// config other pins ...

  /*Configure GPIO pin : PC3 */
  GPIO_InitStruct.Pin = GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
}

However, when running the code, I found that the PC3_C pin provides no output. Then I executed the code with a debugger and inspected the configuration registers. I discovered that SYSCFG_PMCR was set to 0x0F000000 (PC3SO=1), indicating that PC3_C was not connected to PC3. The problem as addressed by modifying the PC3SO bit to 0, as depicted in the figure below. Additionally, similar pins such as PA0_C, PA1_C encountered the same problem.

To ensure a permanent solution, I appended code at the end of the function --

void MX_GPIO_Init(void)
{
// other code ...

  /*Configure GPIO pin : PC3 */
  GPIO_InitStruct.Pin = GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

  HAL_SYSCFG_AnalogSwitchConfig(SYSCFG_SWITCH_PC3, SYSCFG_SWITCH_PC3_CLOSE);
}

Testing has proven that the PC3_C output correctly as the behavior of PC3.

Upon careful examination of CubeMX's graphical user interface, I was unable to locate any information regarding the configuration of SYSCFG_PMCR or its equivalent. Therefore, I suspect that may be a bug within the MPU Package code.

[TOUNSTM]

ST Internal Reference: 172713

[TOUNSTM]

Hello @xiaosiyu0603,

I hope you are fine. The issue you reported has been logged into an internal bug tracker it will be managed by the development team.

As the issue is not related to the software published within this repository, rather to the STM32 ecosystem, no fix is expected to be published here. Hence, please allow me to close it. Thank you for your comprehension.

With regards,