GPIO_EXTI Example Description

How to configure external interrupt lines.

Then the SystemClock_Config() function is used to configure the system clock (SYSCLK) to run at 48 MHz.

In this example, one EXTI line (EXTI_Line13) is configured to generate an interrupt on each falling edge. In the interrupt routine a led connected to a specific GPIO pin is toggled.

In this example:

- EXTI_Line13 is connected to PC.13 pin
- when falling edge is detected on EXTI_Line13 by pressing User push-button, LED1 toggles once

On NUCLEO-C071RB:

- EXTI_Line13 is connected to User push-button

In this example, HCLK is configured at 48 MHz.

Notes

  1. Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds) based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower) than the peripheral interrupt. Otherwise the caller ISR process will be blocked. To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.

  2. The example needs to ensure that the SysTick time base is always set to 1 millisecond to have correct HAL operation.

Keywords

System, GPIO, EXTI, Output, Alternate function, Push-pull, Toggle

Directory contents

Hardware and Software environment

How to use it ?

In order to make the program work, you must do the following :