Toggling LED through button (ESP32 FreeRTOS) + binary semaphore

Question

I had already done several projects using simple freertos ideas: led, button. Implementing semaphores, queues or some interrupt. I can't run this simple code tough.

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"

#include "driver/gpio.h"

#define BLINK_GPIO 21 //2
#define BUTTON_GPIO 0

void task_blink(void *pvParameters);
void task_botao(void *pvParameters);
//void wd_off_task(void *pvParameters);
SemaphoreHandle_t sem_sinc;

void app_main(void)
{
    gpio_pad_select_gpio(BLINK_GPIO); // Configura o pino como IO
    gpio_set_direction(BLINK_GPIO,GPIO_MODE_OUTPUT); // Configura o IO como saida

    gpio_pad_select_gpio(BUTTON_GPIO); // Configura o pino como IO
    gpio_set_direction(BUTTON_GPIO,GPIO_MODE_INPUT); // Configura o IO como entrada

    vSemaphoreCreateBinary(sem_sinc); // Cria o Semaforo
    xSemaphoreTake(sem_sinc,0); // Garante que inicializa com 0

    xTaskCreate(task_blink,"Task Blink",1024,NULL,2,NULL);
    printf("Task Blink Criada!!!\r\n");

    xTaskCreate(task_botao,"Task Botao",1024,NULL,2,NULL);
    printf("Task Botao Criada!!!\r\n");

    //xTaskCreate(wd_off_task,"Task desliga WD",1024,NULL,1,NULL);
}

void task_botao(void *pvParameters)
{
    while(1)
    {
        if(gpio_get_level(BUTTON_GPIO) == 0)
        {
            while(gpio_get_level(BUTTON_GPIO) == 0){}
            printf("Botao Pressionado!!!\r\n");
            xSemaphoreGive(sem_sinc);
            vTaskDelay(1);
        }
    }
}

void task_blink(void *pvParameters)
{
    while(1)
    {
        if(xSemaphoreTake(sem_sinc,portMAX_DELAY)==pdTRUE)
        {
            printf("Pisca Led!!!\r\n");
            if((gpio_get_level(BUTTON_GPIO) == 0))
                gpio_set_level(BLINK_GPIO, 1);
            else
                gpio_set_level(BLINK_GPIO, 0);

        }
    }
}

The issue:

The code is built nicely, and the same for the flashing to ESP. As I press the button, it shows in the terminal the designed messages. See, the only problem here lies on I can't set the LED's level, toggling it! Because of this, all I can get is the LED turning on and turning off afterwards quickly(every time the semaphore syncronizes the 2 tasks).

I suspect it's all about some kind of config, related to this GPIO. (Although I'm using the reset port to read the button, I still think this is not the matter, because the port was properly configured on the lines above)

Answer 1

Your switch polling needs to detect transitions, but avoid erroneously detecting switch bounce as a valid transition. For example:

#define BUTTON_DN = 0 ;
#define BUTTON_UP = 1 ;
#define POLL_DELAY = 50 ;

void task_botao(void *pvParameters)
{
    int button_state = gpio_get_level( BUTTON_GPIO ) ;
    
    for(;;)
    {
        int input_state = gpio_get_level( BUTTON_GPIO ) ;
        
        // If button pressed...
        if( input_state == BUTTON_DN && 
            button_state != BUTTON_UP )
        {
            button_state = BUTTON_DN ;

            // Signal button press event.
            xSemaphoreGive(sem_sinc ) ;
        }
        // otherwise if button released...
        else if( input_state == BUTTON_UP && 
                 button_state != BUTTON_DN )  
        {
            button_state = BUTTON_UP ;
        }
        
        // Delay to yield processor and 
        // avoid switch bounce on transitions 
        vTaskDelay( POLL_DELAY );
    }
}

The blinking task need not be reading the button input at all; not is it unnecessary, it is also a bad design:

void task_blink(void *pvParameters)
{
    int led_state = 0 ;
    gpio_set_level( BLINK_GPIO, led_state ) ;

    for(;;)
    {
        if( xSemaphoreTake( sem_sinc, portMAX_DELAY ) == pdTRUE )
        {
            led_state = !led_state ; 
            gpio_set_level( BLINK_GPIO, led_state ) ;
        }
    }
}