PHP-GPIO
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):
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);
}