README

A simple library to read/write Raspberry PI GPIOs with PHP.

Forked from ronanguilloux/php-gpio and tested with Atoum.

Install

This library can be installed using Composer:

$ composer require tgeindre/php-gpio

Read/Write Raspberry Pi GPIOs

To read/write Raspberry Pi GPIOs, use the PhpGpio\Gpio class. The instanciation of this class requires an array of pins numbers you will use.

You can define a specific list of pins numbers, according to your usage and your Rasberry Pi version, or you can use the PhpGpio\Utils\Pi class to automaticly find all availables pins:

<?php
namespace myproject;

$pi = new PhpGpio\Utils\Pi;
$pi->getAvailablePins(); // int array

Accessing to the GPIOs requires root permissions, so make sure your code is running with enought permissions. Remember: you should never run your webserver as root.

Here is a simple example of Gpio class usage:

<?php
namespace MyProject;

use PhpGpio\GpioInterface;
use PhpGpio\Gpio;

// Both pins are available on all raspi versions
define('PIN_IN', 4);
define('PIN_OUT', 7);

$gpio = new Gpio([PIN_IN, PIN_OUT]);

// First, setup pins with correct directions
$gpio
     ->setup(PIN_IN, GpioInterface::DIRECTION_IN) // Makes it readable
     ->setup(PIN_OUT, GpioInterface::DIRECTION_OUT) // Writeable
;

// read PIN_IN value and display it
$value = $gpio->read(PIN_IN);
var_dump($value); // string

// write 1 on PIN_OUT
$gpio->write(PIN_OUT, GpioInterface::IO_VALUE_ON);
sleep(1);

// After 1 second, write 0 on PIN_OUT
$gpio->write(PIN_OUT, GpioInterface::IO_VALUE_OFF);

// Then free all pins
// (use the unexport() method to free pins one by one)
$gpio->unexportAll();

Check this page if you need a complete list of availables pins on your Raspberry Pi version.

Demo

Here is a simple demo using a Raspberry Pi 3 and some LED (click on the image to see the video):

Source code

Sensors

Currently, this library only supports MCP analogic to digital converter (ADC) with 4 or 8 channels:

MCP3002, MCP3004 & MCP3008

Given that the Rapsberry Pi supports only digital inputs, an ADC, such as a MCP, is required to read analogic data.

MCP3002, MCP3004 and MCP3008 work the same way but have dedicated classes for each version:

PhpGpio\Sensor\Mcp\Mcp3002
PhpGpio\Sensor\Mcp\Mcp3004
PhpGpio\Sensor\Mcp\Mcp3008

It use a SPI interface wich requires, at least, 4 pins:

MISO - Master Input Slave Ouput,
MOSI - Master Output Slave Input,
CLK - Clock,
CS - Channel Select (one dedicated pin for each component using the same SPI interface).

Provided classes use a software communication system so you can use any pins you wich.

Here is the connection schema of those 3 versions of MCP ADC:

Wiring:

VDD (power supply) on 3.3V,
VREF on 3.3v,
AGND on ground (GND),
CLK on clock pin,
DOUT (digital output) on MISO pin,
DIN (digital input) on MOSI pin,
CS (channel select) on CS pin,
DGND on ground (GND).

Now you are ready to read some data:

namespace MyProject;

use PhpGpio\Gpio;
use PhpGpio\Sensor\Mcp\Mcp3008;

// Defining pins mapping according to your setup
$pinsMapping = [
    'MISO' => 17,
    'MOSI' => 8,
    'CLK' => 23,
    'CS' => 24,
];

// Setup a Gpio class
$gpio = new Gpio(array_values($pins));

// Then we can instanciate the MCP class
$mcp = new Mcp3008(
    $gpio
    $mapping['CLK'],
    $mapping['MOSI'],
    $mapping['MISO'],
    $mapping['CS']
);

// Now let's read some data on the first channel
while (true) {
    echo $mcp->read(['channel' => 0]), "\n";
    // every second
    sleep(1);
}

tgeindre / php-gpio

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