How to Send MIDI Messages from PHP: A Step‑by‑Step Guide

As music technology evolves, many instruments support the MIDI (Musical Instrument Digital Interface) protocol, which allows devices from different manufacturers to exchange data. MIDI messages consist of three bytes: a status byte that defines the message type (e.g., 0x90 for "Note On") and two data bytes that carry parameters such as note number and velocity.

Using PHP for MIDI Communication

PHP can interact with MIDI hardware through a serial‑port extension. The following example demonstrates opening a serial port, configuring it for the standard MIDI baud rate (31250), sending a simple Note‑On message (middle C at maximum velocity), and then closing the port.

<?php
// Open serial communication
$serial = new PhpSerial();

$serial->deviceSet("/dev/ttyUSB0");
$serial->confBaudRate(31250);
$serial->confParity("none");
$serial->confCharacterLength(8);
$serial->confStopBits(1);
$serial->confFlowControl("none");

$serial->deviceOpen();

// Send MIDI message
$statusByte = 0x90; // Note On
$dataByte1  = 60;   // Middle C
$dataByte2  = 127;  // Maximum velocity

$message = pack("C*", $statusByte, $dataByte1, $dataByte2);
$serial->sendMessage($message);

// Close serial communication
$serial->deviceClose();
?>

The script creates a PhpSerial instance, sets the device path (e.g., /dev/ttyUSB0), configures the required MIDI parameters, opens the port, packs the three‑byte MIDI message with pack("C*", ...), sends it, and finally closes the connection.

Extending the Example

In real applications you may need to:

Wrap the sending logic in a function to handle different MIDI message types (e.g., Note Off, Control Change).

Implement receiving of MIDI data by reading from the serial port and parsing incoming bytes.

Add error handling and exception management to ensure reliable communication, especially when devices are disconnected or the port is unavailable.

By adapting the basic pattern shown above, developers can build more sophisticated PHP‑based tools for music production, live performance control, or automated testing of MIDI hardware.