Getting started with GPIO

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This article explain what is and how to use GPIO through examplesl

1. GPIO definition

Stands for General Purpose Input/Output. GPIO 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 software.

1.1. Configure GPIO for LED toggling

1.1.1. Objective

Learn how to setup pin and GPIO port in STM32CubeMX
How to Generate Code in STM32CubeMX and use HAL functions

1.1.2. Goal

Configure GPIO pin in CubeMX and Generate Code
Add in to project HAL_Delay function and HAL_GPIO_Toggle function
Verify the correct functionality on toggling LED

1.1.3. Create project in CubeMX

Menu > File > New Project
Select STM32F4 > STM32F429/439 > LQFP144 > STM32F439ZITx
Configure LED pin as GPIO_Output

File:1 GPIO LAB.png

1.1.4. For debug purpose is recommended to select debug pins SWD or JTAG

Select can be done in TAB>Pinout>SYS
On discovery is available only SWD option
If SWD/JTAG is not selected and the Set all free pins as analog (MENU>Project>Settings>TAB>Code Generator) is selected, debug is not possible

File:2 GPIO LAB.png

1.1.4.1. Clock Configuration overview 10

External clock enabling
- TAB>Pinout
- Select HSE and LSE clocks
- Bypass or crystal

File:3 GPIO LAB.png

1.1.4.2. In order to run on maximum frequency, setup clock system

File:4 GPIO LAB.png

1.1.4.3. GPIO Configuration

TAB>Configuration>System>GPIO

File:5 GPIO LAB.png

1.1.4.4. GPIO(Pin) Configuration

Select Push Pull mode
No pull-up and pull-down
Output speed to HIGH is important for faster peripheries like SPI, USART
Button OK

File:6 GPIO LAB.png

1.1.4.5. GPIO(Pin) output speed configuration

Change the rising and falling edge when pin change state from high to low or low to high
Higher GPIO speed increase EMI noise from STM32 and increase STM32 consumption
It is good to adapt GPIO speed with periphery speed. Ex.: Toggling GPIO on 1Hz is LOW optimal settings, but SPI on 45MHz the HIGH must be set

File:7 GPIO LAB.png

1.1.4.6. Now we set the project details for generation

Menu > Project > Project Settings
Set the project name
Project location
Type of toolchain

File:8 GPIO LAB.png

1.1.4.7. Now we can Generate Code

Menu > Project > Generate Code

1.1.4.8. Now we open the project in our IDE

The functions we want to put into main.c

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 */