Communicating with MIDI Devices Using PHP and Serial Ports

With the advancement of music technology, many devices now support the MIDI (Musical Instrument Digital Interface) protocol, enabling communication between instruments from different manufacturers. This article introduces how to use PHP to communicate with MIDI devices and provides a code example.

The MIDI protocol is a digital communication standard that defines the data format and transmission method between musical devices. A MIDI message consists of three bytes: a status byte that specifies the message type, and two data bytes that carry the actual information, such as a Note On command (0x90) and a velocity value.

To communicate with a MIDI device in PHP, you can use a serial communication extension. The following example shows how to open a serial port, configure it for the MIDI baud rate (31250), and send a simple Note On message.

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(); ?>

In the code, a PhpSerial object is instantiated, the device path and parameters (baud rate, parity, etc.) are set, the port is opened with deviceOpen , the MIDI message is sent using sendMessage , and finally the port is closed with deviceClose .

The example is intentionally simple; in real applications you can create functions to send different types of MIDI messages, receive messages from the instrument, and add error‑handling logic to ensure stable communication.

In summary, by using PHP together with the MIDI protocol you can achieve communication with musical hardware. The provided code demonstrates how to send a MIDI Note On message, and readers are encouraged to explore further extensions and applications.

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