(C++) RpiExample2

 

 

Raspberry Pi example 2: turn GPIO pins on and off is a Raspberry Pi example to turn the GPIO pins on and off from command line.

 

• Download the Qt Creator project 'CppRpiExample2' (zip)

Technical facts

 

Operating system(s) or programming environment(s)

• Lubuntu 15.04 (vivid)

IDE(s):

• Qt Creator 3.1.1

Project type:

• Console application

C++ standard:

• C++11

Compiler(s):

• G++ 4.9.2

Libraries used:

• Boost: version 1.55
• STL: GNU ISO C++ Library, version 4.9.2

 

 

 

 

 

Qt project file: ./CppRpiExample2/CppRpiExample2.pro

 

---

TEMPLATE = app CONFIG += console CONFIG -= qt QMAKE_CXXFLAGS += -std=c++0x SOURCES += main.cpp DEFINES += NDEBUG LIBS += -lboost_program_options

 

 

 

 

 

./CppRpiExample2/main.cpp

 

---

#include <cassert> #include <iostream> #include <boost/program_options.hpp> //Thanks to http://www.cl.cam.ac.uk/freshers/raspberrypi/tutorials/temperature/#step-six void SetOutputHigh(const int pin) {   {     const std::string cmd = "echo \"" + boost::lexical_cast<std::string>(pin) + "\" > /sys/class/gpio/export";     std::clog << cmd << '\n';     const int error = std::system(cmd.c_str());     assert(!error);   }   {     const std::string cmd = "echo \"out\" > /sys/class/gpio/gpio" + boost::lexical_cast<std::string>(pin)+ "/direction";     std::clog << cmd << '\n';     const int error = std::system(cmd.c_str());     assert(!error);   }   {     const std::string cmd = "echo \"1\" > /sys/class/gpio/gpio" + boost::lexical_cast<std::string>(pin)+ "/value";     std::clog << cmd << '\n';     const int error = std::system(cmd.c_str());     assert(!error);   } } void SetOutputLow(const int pin) {   {     const std::string cmd = "echo \"0\" > /sys/class/gpio/gpio" + boost::lexical_cast<std::string>(pin)+ "/value";     std::clog << cmd << '\n';     const int error = std::system(cmd.c_str());     assert(!error);   }   {     const std::string cmd = "echo \"" + boost::lexical_cast<std::string>(pin) + "\" > /sys/class/gpio/unexport";     std::clog << cmd << '\n';     const int error = std::system(cmd.c_str());     assert(!error);   } } int main(int argc, char* argv[]) {   // Declare the supported options.   boost::program_options::options_description d("Allowed options for CppRpiExample2");   d.add_options()       ("help",         "produce this help message")       ("pin",          boost::program_options::value<int>(),          "the pin to be modified (must be in pin list)")       ("value",          boost::program_options::value<int>(),          "set the value of a pin (zero or one)")       ("pin_list",          "display the list of pins")       ;   boost::program_options::variables_map m;   boost::program_options::store(     boost::program_options::parse_command_line(       argc, argv, d), m);   boost::program_options::notify(m);   //If one of the options is set to 'help'...   if (m.count("help"))   {     //Display the options_description     std::cout << d << "\n";     return 0;   }   const std::vector<int> pins = { 2,3,4,7,8,9,10,11,14,15,17,18,22,23,24,25,27 };   if (m.count("pin_list"))   {     std::cout << "Pin list:\n";     for(int pin: pins)     {       std::cout << pin << " ";     }     std::cout << '\n';     return 0;   }   int pin = 2;   if (m.count("pin"))   {     pin = m["pin"].as<int>();     std::cout << "pin number: " << pin << '\n';   }   if (std::find(pins.begin(),pins.end(),pin) == pins.end())   {     std::cout << "Pin #" << pin << " is not a valid pin index\n"       << "Use --pin_list for a list of valid pins\n";     return 1;   }   int value = 1;   if (m.count("value"))   {     value = m["value"].as<int>();     std::cout << "value: " << value << '\n';   }   if (value)   {     SetOutputHigh(pin);   }   else   {     SetOutputLow(pin);   } }