Linux Userspace GPIO Library
============================

 * Export and Unexport GPIO pins
 * Interrupt support (*)
 * Hardware-neutral rewrite of NoccyLabs RaspIO 
 * Compatible with psr/logs LoggerInterface for logging

## Interrupts

*NOTE: Not implemented!*

For interrupts to work, you need to first bind the interrupt handler, and then
make sure to call on `Gpio#refresh()` every cycle to poll the interrupt flag on
the selected pins. This is because the `select()` function is used.

    $gpio = new Gpio();

    // Set the handler on the Gpio object
    $gpio->setInterruptHandler($gpio[4], function() { ... });
    // Or like this on the GpioPin.
    $gpio[4]
        ->setEdge("rising")
        ->setHandler(function() { ... });
    
    while (..) {
        ..
        $gpio->refresh();
    }

You can also be risky and use php ticks and timerfuncs (although that might not
be portable/supported/efficient/a good idea):

    declare(ticks=5);
    
    $gpio = new Gpio();
    
    $gpiotick = new GpioTickHandler();
    $gpiotick->registerGpio($gpio);
    
    // The interrupts will now be polled approx every 5th php vm "tick"