#include <Arduino_FreeRTOS.h>
#include "semphr.h"

SemaphoreHandle_t serial_mutex; 

void setup() {
  Serial.begin(9600);

  //how to call a mutex, just ensure to do the include and its
  //handle
  serial_mutex = xSemaphoreCreateMutex();

  xTaskCreate(task1, "print task", 128, NULL, 2, NULL);
  xTaskCreate(task2, "print task", 128, NULL, 2, NULL);
}

void loop() {
  //this code is empty
}

void task1(void *pvParameters){
  while(1){
    if(xSemaphoreTake(serial_mutex, portMAX_DELAY) == pdTRUE){
      Serial.println("Hello from task1");
      xSemaphoreGive(serial_mutex);
      vTaskDelay(1000/portTICK_PERIOD_MS);
    }
  }
}

void task2(void *pvParameters){
  while(1){
    if(xSemaphoreTake(serial_mutex, portMAX_DELAY) == pdTRUE){
      Serial.println("Hello from task2");
      xSemaphoreGive(serial_mutex);
      vTaskDelay(1000/portTICK_PERIOD_MS);
    }
  }
}