handling M5stack button interrupts in FreeRTOS

main.cpp

#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <driver/gpio.h>
#include <M5Stack.h>
#include <esp_log.h>
//#include <Arduino.h>
#include "sdkconfig.h"

#define ESP_INTR_FLAG_DEFAULT 0
#define CONFIG_LOG_DEFAULT_LEVEL 5 // set to debug, check with serial monitor

static const char* TAG = "gpio_button"; // tag for logging
static TaskHandle_t xButtonHandle = NULL; // task handle for interrupt callback

static void IRAM_ATTR vfnButtonISR(void* vpArg) {
  /***
  Interrupt routine for handling GPIO interrupts.
  vpArg is a pointer to the GPIO number.
  ***/
  uint32_t ulGPIONumber = (uint32_t) vpArg; // get the triggering GPIO

  if (gpio_get_level( (gpio_num_t) ulGPIONumber) == 0) { // only when pressed
    xTaskNotifyFromISR(xButtonHandle,     // task to notify
                       ulGPIONumber - 37, // 32 bit integer for passing a value
                       eSetBits,          // notify action (pass value in this case)
                       NULL);             // wake a higher prio task (default behavior)
  }
  portYIELD_FROM_ISR(); // if notified task has higher prio then current interrupted task, set it to the head of the task queue
}

static void vfnButtonTask(void* vpArg) {
  /***
  Task for handling interrupts generated by button presses on the M5Stack
  vpArg is a pointer to the passed arguments. Not used in this task.
  ***/
  uint32_t ulNotifiedValue = 0;
  BaseType_t xResult;

  while (1) {
    m5.Lcd.setCursor(0, 0);
    m5.Lcd.printf("running on core %d", xPortGetCoreID());
    m5.Lcd.setCursor(0, 40);
    xResult = xTaskNotifyWait(pdFALSE,           // don't clear bits on entry
                              0xFFFFFFFF,        // clear all bits on exit
                              &ulNotifiedValue,  // stores the notified value
                              portMAX_DELAY);    // wait forever
    if (xResult == pdPASS) { // if a notification is received
      m5.Lcd.printf("button %d", ulNotifiedValue);
      switch (ulNotifiedValue) { // to demonstrate the use of the switch statement
        case 0:
          ESP_LOGD(TAG, "button 0");
          break;
        case 1:
          ESP_LOGD(TAG, "button 1");
          break;
        case 2:
          ESP_LOGD(TAG, "button 2");
          break;
        default:
          ESP_LOGD(TAG, "This should not happen...");
          break;
      }
    }
  }
  vTaskDelete(NULL); // remove the task whene done
}

extern "C" void app_main() { // ESP32 FreeRTOS application entry point
    ESP_LOGD(TAG, "Starting...");

    gpio_config_t xButtonConfig;
    xButtonConfig.pin_bit_mask = GPIO_SEL_37 | GPIO_SEL_38 | GPIO_SEL_39;
    xButtonConfig.mode         = GPIO_MODE_INPUT;
    xButtonConfig.pull_up_en   = GPIO_PULLUP_DISABLE;
    xButtonConfig.pull_down_en = GPIO_PULLDOWN_ENABLE;
    xButtonConfig.intr_type    = GPIO_INTR_ANYEDGE;
    gpio_config(&xButtonConfig);

    m5.begin();
    m5.Lcd.setTextSize(3);

    xTaskCreatePinnedToCore(vfnButtonTask,  // function with task's code
                            "Button task",  // name
                            2048,           // stack size
                            (void *) NULL,  // input parameters
                            10,             // priority
                            &xButtonHandle, // task handle (for callback from ISR)
                            1);             // core to run on

    gpio_install_isr_service(ESP_INTR_FLAG_DEFAULT);
    gpio_isr_handler_add(GPIO_NUM_39,          // GPIO to attach to
                         vfnButtonISR,         // ISR to call
                         (void*) GPIO_NUM_39); // Parameters to pass
    gpio_isr_handler_add(GPIO_NUM_38, vfnButtonISR, (void*) GPIO_NUM_38);
    gpio_isr_handler_add(GPIO_NUM_37, vfnButtonISR, (void*) GPIO_NUM_37);
}

Note the different notation styles between FreeRTOS (Hungarian notation) and the M5 library (COBOL notation (kebab-case :-) ).