We are going to create a simple application that gradually changes the brightness of an LED connected to a general-purpose pin on a Raspberry Pi board:

1. In your ~/test working directory, create a subdirectory called pwm.
2. Use your favorite text editor to create a pwm.cpp file in the pwm subdirectory.
3. Let's put in the required include functions and define a function called Blink:

#include <chrono>
#include <thread>

#include <wiringPi.h>

using namespace std::literals::chrono_literals;

const int kLedPin = 0;

void Blink(std::chrono::microseconds duration, int percent_on) {
    digitalWrite (kLedPin, HIGH);
    std::this_thread::sleep_for(
            duration * percent_on / 100) ;
    digitalWrite (kLedPin, LOW);
    std::this_thread::sleep_for(
            duration * (100 - percent_on) / 100) ;
}

4. This is followed by a main function:

int main (void)
{
  if (wiringPiSetup () <0) {
    throw std::runtime_error("Failed to initialize wiringPi");
  }

  pinMode (kLedPin, OUTPUT);

  int count = 0;
  int delta = 1;
  while (true) {
    Blink(10ms, count);
    count = count + delta;
    if (count == 101) {
      delta = -1;
    } else if (count == 0) {
      delta = 1;
    }
  }
  return 0 ;
}

5. Create a CMakeLists.txt file containing the build rules for our program:

cmake_minimum_required(VERSION 3.5.1)
project(pwm)
add_executable(pwm pwm.cpp)
target_link_libraries(pwm wiringPi)

6. Connect an LED to your Raspberry Pi board using the instructions from the WiringPI example section at http://wiringpi.com/examples/blink/.
7. Set up an SSH connection to your Raspberry Pi board. Follow instructions from the Raspberry PI documentation section at https://www.raspberrypi.org/documentation/remote-access/ssh/.
8. Copy the contents of the pwm folder to the Raspberry Pi board over SSH.
9. Log in to the board over SSH, then build and run the application:

$ cd pwm && cmake . && make && sudo ./pwm

Your application should now run and you can observe the LED blinking.