allebb/gpio

<?php

namespace Ballen\GPIO\Adapters;

use Ballen\GPIO\Exceptions\GPIOException;
use Ballen\GPIO\Interfaces\AdapterInterface;

/**
 * GPIO
 * A RaspberryPi GPIO library written in PHP.
 *
 * @author Bobby Allen <ballen@bobbyallen.me>
 * @license http://www.gnu.org/licenses/gpl-3.0.html
 * @link https://github.com/allebb/gpio
 * @link http://www.bobbyallen.me
 * @package Ballen\GPIO\Adapters
 * @codeCoverageIgnore
 */
class RPiAdapter implements AdapterInterface
{

    const GPIO_PATH = "/sys/class/gpio";

    /**
     * Set the direction of the pin (input or output)
     *
     * @param int $pin The BCM pin number
     * @param string $direction The type/direction of the pin - Use GPIO::IN and GPIO::OUT
     * @param bool $invert Invert the logic so that high->low and low->high
     * @return bool
     */
    public function setDirection(int $pin, string $direction, bool $invert = false): bool
    {
        $this->export($pin);

        if (file_exists("/sys/class/gpio/gpio{$pin}/direction") && trim(file_get_contents("/sys/class/gpio/gpio{$pin}/direction")) != $direction) {
            system("echo {$direction} > /sys/class/gpio/gpio{$pin}/direction");
        }

        if ($invert) {
            $inverted = intval($invert);
            if (file_get_contents("/sys/class/gpio/gpio{$pin}/active_low") != $inverted) {
                system("echo {$inverted} > /sys/class/gpio/gpio{$pin}/active_low");
            }
        }

        if (file_exists("/sys/class/gpio/gpio{$pin}/direction") && (file_get_contents("/sys/class/gpio/gpio{$pin}/direction") == $direction)) {
            return true;
        }

        return false;

    }

    /**
     * Write a value to an output pin.
     *
     * @param int $pin The BCM pin number.
     * @param int $value The output value (0,1) - Use GPIO::HIGH and GPIO::LOW
     * @return bool
     */
    public function write(int $pin, int $value): bool
    {
        system("echo {$value} > /sys/class/gpio/gpio{$pin}/value");

        if (!file_exists("/sys/class/gpio/gpio{$pin}/value")) {
            return false;
        }

        if (file_get_contents("/sys/class/gpio/gpio{$pin}/value") != $value) {
            return false;
        }

        return true;
    }

    /**
     * Read the value of an input/output pin.
     *
     * @param int $pin The BCM pin number
     * @return int The current value of the pin.
     * @throws GPIOException
     */
    public function read(int $pin): int
    {
        if (!file_exists("/sys/class/gpio/gpio{$pin}/value")) {
            throw new GPIOException("The pin value does not appear to be set, did you forget to run setDirection?");
        }
        return intval(file_get_contents("/sys/class/gpio/gpio{$pin}/value"));
    }

    /**
     * Exports the Pin (enabling it's use)
     *
     * @param int $pin The pin to export/enable.
     * @return bool
     */
    private function export(int $pin): bool
    {
        if (!file_exists("/sys/class/gpio/gpio{$pin}")) {
            system("echo {$pin} > " . self::GPIO_PATH . "/export");
            if (file_exists("/sys/class/gpio/gpio{$pin}")) {
                return true;
            }
        }
        return false;
    }
}