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There are 1 incomplete or pending task to finish installation of Semantic MediaWiki. An administrator or user with sufficient rights can complete it. This should be done before adding new data to avoid inconsistencies.This article explains the EXTI and its use, with examples.
1 External interrupt/event controller (EXTI)
The external interrupt/event controller consists of up to 23 edge detectors for generating event/interrupt requests. Each input line can be independently configured to select the type (interrupt or event) and the corresponding trigger event (rising, falling, or both).
2 Configure EXTI to turn on an LED when a user button is pressed
2.1 Objective
- Set up an input pin with EXTI in STM32CubeMX.
- Generate code in STM32CubeMX and use HAL functions.
2.2 How
- Configure a GPIO and EXTI pin in STM32CubeMX and generate code.
- Add into a project: a callback function, and a function to turn on an LED.
- Verify the correct functionality by pressing a button that turns on an LED.
2.3 Create project in STM32CubeMX
- Menu > File > New Project
- Select STM32F439ZITx
- Configure an LED pin as GPIO_Output (PG14 on NucleoF439ZI). For other boards check their user manual.
File:LED UM.png File:LED PIN.png
- Configure a button pin as GPIO_EXTIX (PA0 on NucleoF439ZI). For other boards check their user manual.
- GPIO configuration check
- Enable the interrupt for EXTI
- Save your project and generate the code for your IDE.
2.4 HAL Library workflow summary
2.5 Open your IDE
Create a function to handle the EXTI interrupts:
- HAL callback function for EXTI: void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
- To turn an LED on we need to use the function: HAL_GPIO_WritePin
Put the functions into main.c
/* USER CODE BEGIN 4 */
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
if(GPIO_Pin == GPIO_PIN_0) {
HAL_GPIO_WritePin(GPIOG, GPIO_PIN_14, GPIO_PIN_SET);
} else {
__NOP();
}
}
/* USER CODE END 4 */
2.6 Compile and Flash
Compile the above code, then load it to the board flash memory.
- When you press the blue button on your board the LED must switch on.