yukiworkshop / gpioplusplus

Easy-to-use C++ library for the new Linux GPIO API

GPIO++

Easy-to-use C++ library for the new Linux GPIO API.

Features

• OOP design
• Elegant event handling: automatic or manual
• Finds your desired pin by name (need DT/ACPI support)
• Not limited to a specific hardware platform
• Thread safe
• Doesn't look like Arduino APIs :P

Requirements

• Linux kernel 4.8+ with new GPIO API (/dev/gpiochipX) & epoll
• Linux kernel 5.4+ to make pullup/pulldown actually working

And reasonably new versions of:

• C++17 compatible compiler
• CMake

Install

Use of the CPM package manager is recommended.

include(cmake/CPM.cmake)

CPMAddPackage(
        NAME GPIOPlusPlus
        GITHUB_REPOSITORY YukiWorkshop/GPIOPlusPlus
        VERSION 0.0.5
)

target_include_directories(your_project PUBLIC ${GPIOPlusPlus_SOURCE_DIR})
target_link_libraries(your_project GPIOPlusPlus pthread)

Usage

#include <GPIO++.hpp>

using namespace YukiWorkshop;

Get all available devices:

std::vector<GPIO::Device> devs = GPIO::all_devices();

All operations should be surrounded by try and catch. The exception type is std::system_error unless otherwise specified.

Open a device by number:

try {
    auto d = GPIO::Device(0);
} catch (std::system_error& e) {
    // Error handling here
    std::cerr << "Oops! " << e.what() << "\n";
}

...or by path:

auto d = GPIO::Device("/dev/gpiochip0");

...or by label:

try {
    auto d = GPIO::find_device_by_label("pinctrl-bcm2835");
} catch (std::logic_error &e) {
    // No device with this label
}

Basic line operations:

auto line0 = d.line(0, GPIO::LineMode::Input | GPIO::LineMode::PullUp);
printf("Line 0: %s\n", line0.read() ? "HIGH" : "LOW");

auto line1 = d.line(1, GPIO::LineMode::Output);
line1.write(1);

Get a line by its name (won't work if it doesn't have one in device tree):

auto line0 = d.line(d.lines_by_name["SDA1"], GPIO::LineMode::Input);

Add events:

int handle = d.add_event(2, GPIO::LineMode::Input, GPIO::EventMode::RisingEdge,
               [](GPIO::EventType evtype, uint64_t evtime){
                   std::cout << "Hey man, your pin is HIGH at " << evtime << "\n";
               }
);

And remove them:

d.remove_event(handle);

Automatic events handling:

std::thread t([&](){
    d.run_eventlistener();
});

And stop them:

d.stop_eventlistener();
t.join();

Manual events handling:

int epfd = epoll_create(42);

epoll_event ev;

for (auto &it : d.event_fds()) {
    ev.events = EPOLLIN;
    ev.data.fd = it;

    epoll_ctl(epfd, EPOLL_CTL_ADD, it, &ev);
}

int ep_rc;
epoll_event evs[16];

while ((ep_rc = epoll_wait(epfd, evs, 16, 1000)) != -1) {
    if (ep_rc > 0) {
        for (uint i=0; i<ep_rc; i++)
            d.process_event(evs[i].data.fd);
    }

    // ...
}

No more digitalWrites!! Hurray!!!!!!

License

LGPLv3