main.cpp

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

#define LED0_PATH "/sys/class/leds/beaglebone:green:usr0"

void removeTrigger(){
   // remove the trigger from the LED
   std::fstream fs;
   fs.open( LED0_PATH "/trigger", std::fstream::out);
   fs << "none";
   fs.close();
}

int main(int argc, char* argv[]){
   if(argc!=2){
    cout << "Usage is makeLED and one of: on, off, flash or status"
<< endl;
    cout << "e.g. makeLED flash" << endl;
   }

   string cmd(argv[1]);
   std::fstream fs;
   cout << "Starting the LED flash program" << endl;
   cout << "The LED Path is: " << LED0_PATH << endl;

   // select whether it is on, off or flash
   if(cmd=="on"){
    removeTrigger();
    fs.open (LED0_PATH "/brightness", std::fstream::out);
    fs << "1";
    fs.close();
   }
   else if (cmd=="off"){
    removeTrigger();
    fs.open (LED0_PATH "/brightness", std::fstream::out);
    fs << "0";
    fs.close();
   }
   else if (cmd=="flash"){
    fs.open (LED0_PATH "/trigger", std::fstream::out);
    fs << "timer";
    fs.close();
    fs.open (LED0_PATH "/delay_on", std::fstream::out);
    fs << "50";
    fs.close();
    fs.open (LED0_PATH "/delay_off", std::fstream::out);
    fs << "50";
    fs.close();
   }
   else if (cmd=="status"){
    // display the current trigger details
    fs.open( LED0_PATH "/trigger", std::fstream::in);
    string line;
    while(getline(fs,line)) cout << line;
    fs.close();
   }
   else{
    cout << "Invalid command" << endl;
   }
   cout << "Finished the LED flash program" << endl;
   return 0;
}