Internal Pull up STM32G4 series

[STUser34]

Hello,

I am using the internal pull up for the input pins, but when read the port status using the program, it always reads 0 instead of 1. I expected it to read 1 and if make that pin grounded it shall read 0. 

[Hl_st]

Hello,

can you also share complete configuration of these pins?

Thank you

[STUser34]

This is the code

#define ON 1

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

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOF_CLK_ENABLE();
  __HAL_RCC_GPIOG_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();
  
   /* USER CODE BEGIN  */

  /*Configure GPIO pin Output Level */
 // HAL_GPIO_WritePin(GPIOB, GPIO_PIN_11, GPIO_PIN_RESET);

  /*Configure GPIO pin : PB11 */
  GPIO_InitStruct.Pin = GPIO_PIN_11;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = GPIO_PIN_12|GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  /*Configure GPIO pins : PC6 PC7 PC8 */
  GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_8;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

  /*Configure GPIO pins : PA8 PA9 PA10 */
  GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9|GPIO_PIN_10;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
  /* USER CODE END  */
}
MC_VehicleMode_Status_t SetVehicleMode(MCI_Handle_t *pHandle)
{
    uint8_t l_portb_pin11_state_u8=0;
    uint8_t l_portb_pin12_state_u8=0;
    uint8_t l_porta_pin8_state_u8=0;
    uint8_t l_portc_pin7_state_u8 = 0;
    uint8_t l_portb_pin15_state_u8 = 0;
    uint8_t l_porta_pin9_state_u8 = 0;

    l_portb_pin11_state_u8 = HAL_GPIO_ReadPin(GPIOB,GPIO_PIN_11);
    l_portb_pin12_state_u8 = HAL_GPIO_ReadPin(GPIOB,GPIO_PIN_12);
    
    if(l_portb_pin11_state_u8 == ON)
    {
        pHandle->VehicleMode = MCM_REVERSE_MODE;
    }
    else if(l_portb_pin12_state_u8 == ON)
    {
        pHandle->VehicleMode = MCM_CITY_MODE;
    }
}

But in the code when i debug it always reads as 0 instead of 1. I have added only the main section of the code. Please let me know if anything else to be shared or added.

[Ozone]

I suppose the values are consistent with the input register values of the GPIO in the debugger.

Have you tried a, say, 5k external pull-up resistor ?
And have you physically measured the voltage on the respective pins ?

[STUser34]

At present i did not give provision for external pull up resistor, i want to use the internal pull up feature of the micro. If i want to make the pin low then i provide a ground to detect switch pressed.

Switch not pressed -> micro internal pull up -> gpio reads 1

Switch pressed -> micro pin shorted to ground -> gpio shall read 0. 

The above is the idea i want to use.

[Hl_st · Accepted solution]

I couldn´t see anything wrong in your code. I tried to do some easy example and it works right and pin input value is also seen in debugger. Do you have connected anything externally to MCU pins? 

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

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

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  /* USER CODE BEGIN 2 */
  /* USER CODE END 2 */

  /* Infinite loop */
  while (1)
  {
    HAL_GPIO_WritePin(USER_LED_GPIO_Port, USER_LED_Pin, 
                      HAL_GPIO_ReadPin(INPUT_PULL_UP_GPIO_Port, INPUT_PULL_UP_Pin));
  }
}

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

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOF_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(USER_LED_GPIO_Port, USER_LED_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin : INPUT_PULL_UP_Pin */
  GPIO_InitStruct.Pin = INPUT_PULL_UP_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(INPUT_PULL_UP_GPIO_Port, &GPIO_InitStruct);

  /*Configure GPIO pin : USER_LED_Pin */
  GPIO_InitStruct.Pin = USER_LED_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(USER_LED_GPIO_Port, &GPIO_InitStruct);
}

[STUser34]

Ok i will check and update you.

[STUser34]

Yes there is some problem in the circuit i will try the below circuit, initially it was planned to give 12V as input now i feel it is not required.

[Ozone]

I know from other STM32 parts that the internal pull-up is relatively weak, usually between 40 and 50kOhm.
In connection with your external circuitry - the 4k resistor to ground - you effectively have a pull-down configuration.

[STUser34]

Yes i will remove that 4K resistor and check, should i remove the series 1k and 10K resistor as well?