Getting Started Tutorial Using HAL Library, STM32CubeMX and Keil 5 Development (Part 2): GPIO

The article is reproduced from http://blog.csdn.net/charmingsun/article/details/52095563. For the use of software and other preparations, please refer to: Getting Started Tutorial Using HAL Library, STM32CubeMX and Keil 5 Development (I): Lighting up an LED (NUCLEO-F411RE)

the STM32F4xx HAL driver manual .

2. GPIO usage examples

Example function: Use the button (PC13) to flip the LED (PA5) level state. 
1. Use STM32CubeMX to configure the pin function and nested vector interrupt controller: 
Configure the LED light pin to output mode 

Connect the button pin to the external interrupt line 13 

Click the GPIO configuration button 

Select the GPIO mode as the rising edge triggered external interrupt mode 
(what is rising edge triggered, what is external interrupt, and other modes, please Baidu yourself) 

Click the Nested Vectored Interrupt Controller Configuration button 

Check to enable external interrupt lines 10~15 and generate the corresponding initialization code 
 

2. Define the external interrupt callback function at the corresponding position in the generated project:

/* USER CODE BEGIN 4 */
void HAL_GPIO_EXTI_Callback (uint16_t GPIO_Pin)
{    if(GPIO_Pin == GPIO_PIN_13)
        HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
}

/* USER CODE END 4 */

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3. Compile and download the program to the development board, and reset the development board.

3. Code Analysis

1. Register the EXTI15_10_IRQHandler function as the interrupt service function of external interrupt lines 10 to 15 in the startup file startup_stm32f411xe.s of the development board. When external interrupt lines 10 to 15 generate an external interrupt, the hardware calls the EXTI15_10_IRQHandler function to interrupt the currently running program. The CPU starts to execute the program in the interrupt service function, and after execution, continues to run the program before the interruption.

2. Because the hardware structure of STM32F4 determines that external interrupt lines 10 to 15 share an interrupt vector, only one interrupt service function can be registered. The HAL framework uses the HAL_GPIO_EXTI_IRQHandler() function and the HAL_GPIO_EXTI_Callback() function to make it appear to the user that each external interrupt line has its own interrupt service function (these two functions will be explained later);

3. The EXTI15_10_IRQHandler function is defined in the stm32f4xx_it.c file, which calls the HAL_GPIO_EXTI_IRQHandler(GPIO_PIN_13); statement;

4. HAL_GPIO_EXTI_IRQHandler() is defined in the stm32f4xx_hal_gpio.c file. This function determines which external interrupt line generates the external interrupt, clears the corresponding bit in the interrupt pending register, and then calls the external interrupt callback function HAL_GPIO_EXTI_Callback(), and passes the interrupt line that generates the external interrupt as a parameter to the external interrupt callback function HAL_GPIO_EXTI_Callback();

5. All the above work is done by STM32CubeMX for us. We only need to redefine the HAL_GPIO_EXTI_Callback() function in the main.c file;

6. Because all external interrupts will call the HAL_GPIO_EXTI_Callback() function, we need to determine which external interrupt line has generated the external interrupt based on the input GPIO_Pin parameter in the HAL_GPIO_EXTI_Callback() function, and then execute different codes according to different external interrupts;

7. Therefore, we use the statement if(GPIO_Pin == GPIO_PIN_13) to determine whether the external interrupt is generated by external interrupt line 13, and then execute the HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5); statement to flip the level state of the LED light;

Tips: We should not execute too much code in the interrupt service function or interrupt callback function to minimize interrupt nesting. For information about interrupt nesting and interrupt priority, please search Baidu. Interrupt priority (not limited to external interrupts) can be set in NVIC Configuration in STM32CubeMX.