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3. Button control (EXTI)

Button control

Button control1. Software-Hardware2. Brief principle1. Hardware schematic diagram2. Physical connection diagram3. Control principle3. Project configuration1. Description2. Pin configuration4. Main functions1. User function2. HAL library function analysis5. Experimental phenomena

This tutorial demonstrates: triggering an external interrupt through GPIO input, and controlling the LED and buzzer according to the key that triggers the interrupt.

1. Software-Hardware

STM32F103CubeIDE
STM32 Robot Development Board
GPIO: chip internal peripherals
Buttons, LEDs and active buzzer: onboard
Type-C data cable or ST-Link
Download programs or simulate the development board

2. Brief principle

1. Hardware schematic diagram

2. Physical connection diagram

3. Control principle

Trigger an external interrupt by pressing a button, and control the LED to turn on and off and the buzzer to sound according to the triggered button.

LED: High level lights up, low level turns off

LED(schematic name)	control pin	Function
LED1	PG14	Control LED1 to turn on and off
LED2	PG15	Control LED2 to turn on and off

KEY: High level by default, low level when the button is pressed

KEY(schematic name)	control pin	Function
KEY1	PG3	Change the KEY1 pin level state
KEY2	PG4	Change the KEY2 pin level state
KEY3	PG5	Change the KEY3 pin level state

Buzzer: High level sounds, low level does not sound

Buzzer(schematic name)	control pin	Function
Buzzer	PG12	Control the buzzer sound

NVIC (Nested Vectored Interrupt Controller)

NVIC controls the interrupt-related functions of the entire chip and provides a reliable interrupt handling mechanism for the system.

Interrupt Priority

Preemption priority: The preemption priority is used to determine the relative priority between interrupts. When an interrupt with a high preemption priority occurs, it can interrupt the executing interrupt with a low preemption priority;

Response priority: When multiple interrupt sources have the same preemption priority, the interrupt with high response priority will be processed first and will not be interrupted by interrupts with the same preemption priority but low response priority.

EXTI (External Interrupt)

The external interrupt/event controller consists of 19 edge detectors that generate event/interrupt requests.

Each input line can be independently configured with input type (pulse or suspend) and corresponding trigger event (rising edge, falling edge, or both edges), and each input line can be independently shielded.

External Interrupt/Event Line Image


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EXTI0~EXIT4 each have independent interrupt channels
EXTI5~EXIT9 share the same interrupt channel: EXTI9_5_IRQ
EXTI10~EXIT15 share the same interrupt channel: EXTI15_10_IRQ

KEY(schematic name)	control pin	External interrupt service function
KEY1	PG3	EXTI3_IRQHandler function
KEY2	PG4	EXTI4_IRQHandler function
KEY3	PG5	EXTI9_5_IRQHandler function

This section tutorial external interrupt trigger mode: rising edge trigger.

3. Project configuration

Project configuration: Prompt configuration options during STM32CubeIDE project configuration

1. Description

Omitted project configuration part: New project, chip selection, project configuration, SYS of pin configuration, RCC configuration, clock configuration and project configuration content

The project configuration part that is not omitted is the key point that needs to be configured in this tutorial.


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Please refer to [2. Development environment construction and use: STM32CubeIDE installation and use] to understand how to configure the omitted parts of the project.

2. Pin configuration

Configure specified pin function

You can directly select the corresponding pin number in the pin view, and the corresponding options will appear when you left-click the mouse.

GPIO

NVIC

Later, when it comes to modifying the interrupt priority, you need to enter the NVIC interface settings. The default priority is used here.

Advanced Settings

Generate code

4. Main functions

It mainly introduces the functional code written by the user. For detailed code, you can open the project file provided by us yourself and enter the Bsp folder to view the source code. **

1. User function

function ：Set_led

function prototype	void Set_led(uint8_t id, uint8_t i)
Function description	Set the LED to turn on and off
Input parameter 1	id：LED id（1：LED1，2：LED2）
Input parameter 2	i：Switch (0: off, 1: on)
return value	none

2. HAL library function analysis

The HAL library functions that have been introduced in the previous tutorial will not be introduced again in the tutorial!


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If you want to find the HAL library and LL library function analysis involved in the entire tutorial, you can view the documents in the folder [8. STM32 Manual: STM32F1_HAL Library and LL Library_User Manual]

function ：HAL_NVIC_SetPriority

function prototype	void HAL_NVIC_SetPriority(IRQn_Type IRQn, uint32_t PreemptPriority, uint32_t SubPriority)
Function description	Configure interrupt priority
Input parameter 1	IRQn：Interrupt source
Input parameter 2	PreemptPriority
Input parameter 3	SubPriority
return value	none

function ：HAL_NVIC_EnableIRQ

function prototype	void HAL_NVIC_EnableIRQ(IRQn_Type IRQn)
Function description	Enable interrupt source
Input parameter	IRQn: interrupt source
return value	none

function ：HAL_GPIO_EXTI_IRQHandler

function prototype	void HAL_GPIO_EXTI_IRQHandler(uint16_t GPIO_Pin)
Function description	General processing function after all external interrupts occur
Input parameter	GPIO_Pin: pin of external interrupt source
return value	none

function ：HAL_GPIO_EXTI_Callback

function prototype	void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
Function description	External interrupt callback function
Input parameter	GPIO_Pin: pin of external interrupt source
return value	none
Precautions	1. This function is called by the external interrupt general processing function HAL_GPIO_EXTI_IRQHandler 2. This function is used to handle specific interrupt tasks

5. Experimental phenomena

After downloading the program successfully, press the RESET button of the development board and observe the development board phenomenon!


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For program download, please refer to [2. Development environment construction and use: program download and simulation]

Phenomenon:

Press the KEY1 button and release it: the buzzer will not sound, LED1 and LED2 will turn off

Press the KEY2 button and release: LED1 lights up

Press the KEY3 button and release: the buzzer sounds and LED2 lights up


For experimental phenomena, please see [Button Control_Experimental Phenomenon.mp4]

Buzzer control (GPIO)

Serial communication (UASRT)