Home | Projects | Notes > MCU Peripheral Drivers > GPIO Application 4: Toggling LED with External Button Interrupt (gpio_04_led_toggle_with_ext_button_interrupt.c)

GPIO Application 4: Toggling LED with External Button Interrupt (gpio_04_led_toggle_with_ext_button_interrupt.c)

Requirements

• Connect an external button to PD6 pin and toggle the LED whenever the interrupt is triggered by the button press.

• Interrupt should be triggered during the falling edge of the button press.

Code

gpio_04_led_toggle_with_ext_button_interrupt.c

Path: Project/Src/

xxxxxxxxxx
80
1
/*******************************************************************************
2
 * File     : gpio_04_led_toggle_with_ext_button_interrupt.c
3
 * Brief    : Program to toggle LED whenever an interrupt is triggered by the
4
 *            the external button press
5
 * Author   : Kyungjae Lee
6
 * Date     : May 24, 2023
7
 ******************************************************************************/
8

9
#include <string.h>
10
#include "stm32f407xx.h"
11

12
#define HIGH            1
13
#define LOW             0
14
#define BTN_PRESSED     LOW
15

16
/**
17
 * delay()
18
 * Brief    : Spinlock delays the program execution
19
 * Param    : None
20
 * Retval   : None
21
 * Note     : N/A
22
 */
23
void delay(void)
24
{
25
    /* Appoximately ~200ms delay when the system clock freq is 16 MHz */
26
    for (uint32_t i = 0; i < 500000 / 2; i++);
27
} /* End of delay */
28

29

30
int main(int argc, char *argv[])
31
{
32
    GPIO_Handle_TypeDef GPIOLed, GPIOBtn;
33

34
    /* Zero-out all the fields in the structures (Very important! GPIOLed and GPIOBtn
35
     * are local variables whose members may be filled with garbage values before
36
     * initialization. These garbage values may set (corrupt) the bit fields that
37
     * you did not touch assuming that they will be 0 by default. Do NOT make this
38
     * mistake!
39
     */
40
    memset(&GPIOLed, 0, sizeof(GPIOLed));
41
    memset(&GPIOBtn, 0, sizeof(GPIOBtn));
42

43
    /* GPIOLed configuration */
44
    GPIOLed.pGPIOx = GPIOD;
45
    GPIOLed.GPIO_PinConfig.GPIO_PinNumber = GPIO_PIN_12;
46
    GPIOLed.GPIO_PinConfig.GPIO_PinMode = GPIO_PIN_MODE_OUT;
47
    GPIOLed.GPIO_PinConfig.GPIO_PinSpeed = GPIO_PIN_OUT_SPEED_HIGH;
48
    GPIOLed.GPIO_PinConfig.GPIO_PinOutType = GPIO_PIN_OUT_TYPE_PP;
49
    GPIOLed.GPIO_PinConfig.GPIO_PinPuPdControl = GPIO_PIN_NO_PUPD;
50
    GPIO_Init(&GPIOLed);
51

52
    /* GPIOBtn configuration */
53
    GPIOBtn.pGPIOx = GPIOD;
54
    GPIOBtn.GPIO_PinConfig.GPIO_PinNumber = GPIO_PIN_6;
55
    GPIOBtn.GPIO_PinConfig.GPIO_PinMode = GPIO_PIN_MODE_IT_FT;  /* Interrupt falling-edge */
56
    GPIOBtn.GPIO_PinConfig.GPIO_PinSpeed = GPIO_PIN_OUT_SPEED_HIGH; /* Doesn't matter */
57
    //GPIOBtn.GPIO_PinConfig.GPIO_PinOutType = GPIO_PIN_OUT_TYPE_PP;    /* N/A */
58
    GPIOBtn.GPIO_PinConfig.GPIO_PinPuPdControl = GPIO_PIN_PU;
59
    GPIO_Init(&GPIOBtn);
60

61
    /* IRQ configurations */
62
    GPIO_IRQPriorityConfig(IRQ_NO_EXTI9_5, NVIC_IRQ_PRI15); /* Optional in this case */
63
    GPIO_IRQInterruptConfig(IRQ_NO_EXTI9_5, ENABLE);    /* EXTI 9 to 5 */
64

65
    while (1);
66
} /* End of main */
67

68
/**
69
 * EXTI9_5_IRQHandler()
70
 * Brief    : Handles interrupt requests coming through EXTI lines 5-9
71
 * Param    : None
72
 * Retval   : None
73
 * Note     : N/A
74
 */
75
void EXTI9_5_IRQHandler(void)
76
{
77
    delay(); /* Debounding time */
78
    GPIO_IRQHandling(GPIO_PIN_6);   /* Clear the pending event from EXTI line */
79
    GPIO_ToggleOutputPin(GPIOD, GPIO_PIN_12);
80
} /* End of EXTI9_5_IRQHandler */