Difference between revisions of "Getting started with GPIO"

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This article explains what is GPIO and how to use it through examples

1 GPIO definition[edit]

GPIO stands for general purpose input/output. It is a type of pin found on an integrated circuit that does not have a specific function. While most pins have a dedicated purpose, such as sending a signal to a certain component, the function of a GPIO pin is customizable and can be controlled by the software.

2 Configure GPIO for LED toggling[edit]

2.1 Objective[edit]

  • Learn how to setup the pin and GPIO port in STM32CubeMX
  • Modify the code generated by STM32CubeMX and use the HAL functions

2.2 How[edit]

  • Configure the GPIO pin in STM32CubeMX and generate the code
  • Add into the project the HAL_Delay function and HAL_GPIO_Toggle function
  • Verify the correct functionality on toggling LED

2.3 Create the project in STM32CubeMX[edit]

  • New project > Access to board selector on main panel or Menu > File > New Project
  • Select NUCLEO-L476RG

SelectL476.png

  • If you want to start the project with a board, the LED pin is already selected (PA5 on NucleoL476RG. For other boards refer to the user manual)

LedPinGPIO.png LED UM GPIO.png

Note: During the download of a firmware package with STM32CubeMX, existing examples can be find at the following path for example: c:\Users\YourUserName\STM32Cube\Repository\STM32Cube_FW_G0_V1.3.0\Projects\NUCLEO-G071RB\Examples\GPIO\GPIO_IOToggle\GPIO_IOToggle.ioc and open them with STM32CubeMX.

2.3.1 GPIO configuration[edit]
  • Select the push-pull mode
  • No pull-up and pull-down
  • Output speed set to very high is important for faster peripherals such as SPI or USART.

GPIO config.png

2.3.2 GPIO (pin) output-speed configuration[edit]
  • Change the rising and falling edge when the pin state changes from high to low or low to high.
  • A higher GPIO speed increases the EMI noise from STM32 and increases the STM32 consumption.
  • It is good to adapt the GPIO speed with the peripheral speed. For example toggling GPIO on 1 Hz is low optimal settings, but with SPI on 45 MHz the very high must be set..

GPIO Speed.png

2.3.3 Set the project details for generation[edit]

Manage GPIO Project.png

2.3.4 Open the main.c in our IDE[edit]
  • We do the LED toggling in a function inside main.c
Info white.png Information
Between /* USER CODE BEGIN 3 */ and /* USER CODE END 3 */ tags
 /* USER CODE BEGIN 3 */
  /* Infinite loop */
  while (1)
  {
    HAL_GPIO_WritePin(GPIOG, GPIO_PIN_14, GPIO_PIN_SET);
    HAL_Delay(500);
    
    HAL_GPIO_WritePin(GPIOG, GPIO_PIN_14, GPIO_PIN_RESET);
    HAL_Delay(500);
  }
  /* USER CODE END 3 */

2.4 Compile and flash[edit]

  • Every 500 ms the green LED state changes.
Warning white.png Warning
All GPIOs are able to drive 5 V and 3 V in input mode, but they are only able to generate 3 V in output push-pull mode




This article explains what is GPIO and how to use it through examples
==GPIO definition==
'''''GPIO''''' stands for '''''general purpose input/output'''''. It is a type of pin found on an integrated circuit that does not have a specific function. While most pins have a dedicated purpose, such as sending a signal to a certain component, the function of a GPIO pin is customizable and can be controlled by the software.
==Configure GPIO for LED toggling==
====Objective====
* Learn how to setup the pin and GPIO port in STM32CubeMX
* Modify the code generated by STM32CubeMX and use the HAL functions

====How====
* Configure the GPIO pin in STM32CubeMX and generate the code
* Add into the project the HAL_Delay function and HAL_GPIO_Toggle function
* Verify the correct functionality on toggling LED

====Create the project in STM32CubeMX====
* '''''New project''''' > '''''Access to board selector''''' on main panel or '''''Menu''''' > '''''File''''' > '''''New Project'''''
* Select  NUCLEO-L476RG
[[File:SelectL476.png|600px]]
* If you want to start the project with a board, the LED pin is already selected (PA5 on NucleoL476RG. For other boards  refer to the user manual)
[[File:LedPinGPIO.png|300px]]
[[File:LED_UM_GPIO.png|300px]]

Note: During the download  of a firmware package with STM32CubeMX, existing examples can be find at the following path for example: 
'''''c:\Users\YourUserName\STM32Cube\Repository\STM32Cube_FW_G0_V1.3.0\Projects\NUCLEO-G071RB\Examples\GPIO\GPIO_IOToggle\GPIO_IOToggle.ioc'''''
and open them with STM32CubeMX.

=====GPIO configuration=====
* Select the push-pull mode
* No pull-up and pull-down
* Output speed set to very high is important for faster peripherals such as SPI or USART.
[[File:GPIO_config.png|600px]]

=====GPIO (pin) output-speed configuration=====
* Change the rising and falling edge when the pin state changes from high to low or low to high.
* A higher GPIO speed increases the EMI noise from STM32 and increases the STM32 consumption.
* It is good to adapt the GPIO speed with the peripheral speed. For example toggling GPIO on 1 Hz is '''''low''''' optimal settings, but with SPI on 45 MHz the '''''very high''''' must be set..
[[File:GPIO_Speed.png|600px]]

=====Set the project details for generation=====
[[File:Manage_GPIO_Project.png|600px]]
=====Open the main.c in our IDE=====
* We do the LED toggling in a function inside '''''main.c'''''
{{Info|Between '''/* USER CODE BEGIN 3 */''' and '''/* USER CODE END 3 */''' tags}}<syntaxhighlight lang="c">

 /* USER CODE BEGIN 3 */
  /* Infinite loop */
  while (1)
  {
    HAL_GPIO_WritePin(GPIOG, GPIO_PIN_14, GPIO_PIN_SET);
    HAL_Delay(500);

    HAL_GPIO_WritePin(GPIOG, GPIO_PIN_14, GPIO_PIN_RESET);
    HAL_Delay(500);
  }
  /* USER CODE END 3 */</syntaxhighlight>


====Compile and flash====
*Every 500 ms the green LED state changes.
{{Warning |  All GPIOs are able to drive 5 V and 3 V in input mode, but they are only able to generate 3 V in output push-pull mode}}
<noinclude>

{{ArticleBasedOnModel | Example STM32 features/examples article}}
{{PublicationRequestId | 23751 | 2022-06-13 | }}
{{PublicationRequestId | 17185 | 2020-08-26 | Alain FONTBONNE}}
[[category:Getting_started_with_STM32_system_peripherals | 15]]</noinclude>
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This article explains what is GPIO and how to use through examples
+
This article explains what is GPIO and how to use it through examples
 
==GPIO definition==
 
==GPIO definition==
 
'''''GPIO''''' stands for '''''general purpose input/output'''''. It is a type of pin found on an integrated circuit that does not have a specific function. While most pins have a dedicated purpose, such as sending a signal to a certain component, the function of a GPIO pin is customizable and can be controlled by the software.
 
'''''GPIO''''' stands for '''''general purpose input/output'''''. It is a type of pin found on an integrated circuit that does not have a specific function. While most pins have a dedicated purpose, such as sending a signal to a certain component, the function of a GPIO pin is customizable and can be controlled by the software.