We will create an application that will define the Watchdog class and provide an example of its usage. Follow these steps:

1. In your working directory, that is, ~/test, create a subdirectory called watchdog.
2. Use your favorite text editor to create a file called watchdog.cpp in the watchdog subdirectory.
3. Put the required includes in the watchdog.cpp file:

#include <chrono>
#include <iostream>
#include <thread>

#include <unistd.h>

using namespace std::chrono_literals;

4. Next, we define the Watchdog class itself:

class Watchdog {
  std::chrono::seconds seconds;

  public:
    Watchdog(std::chrono::seconds seconds):
      seconds(seconds) {
        feed();
    }

    ~Watchdog() {
      alarm(0);
    }

    void feed() {
      alarm(seconds.count());
    }
};

5. Add the main function, which serves as a usage example for our watchdog:

int main() {
  Watchdog watchdog(2s);
  std::chrono::milliseconds delay = 700ms;
  for (int i = 0; i < 10; i++) {
    watchdog.feed();
    std::cout << delay.count() << "ms delay" << std::endl;
    std::this_thread::sleep_for(delay);
    delay += 300ms;
  }
}

6. Add a CMakeLists.txt file containing the build rules for our program:

cmake_minimum_required(VERSION 3.5.1)
project(watchdog)
add_executable(watchdog watchdog.cpp)

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

SET(CMAKE_CXX_FLAGS "--std=c++14")

set(CMAKE_CXX_COMPILER /usr/bin/arm-linux-gnueabi-g++)

7. You can now build and run the application.