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);
}