BLEMIDI-Adapter.ino

BLEMIDI-Adapter

Turns an Arduino into a Bluetooth Low Energy (BLE) to 5-pin DIN MIDI adapter.

Boards: 🛈

Nano 33 IoT, Nano 33 BLE, ESP32, ESP32-S3, Pi Pico W

Configuration

• If you're using a Pi Pico W, you'll have to enable the Bluetooth stack from the Tools > IP/Bluetooth Stack menu in the IDE.
• If you're using an ESP32, you can optionally switch to the NimBLE backend by installing the h2zero/NimBLE-Arduino library, and adding #define CS_USE_NIMBLE at the top of this sketch.
• If you're using a newer ESP32-based chip like the ESP32-S3, with arduino-esp32 version 3.3.0 or later, the NimBLE backend is enabled by default, without requiring the h2zero/NimBLE-Arduino library.
• If you're not using a Pico or an ESP32, you'll have to install the ArduinoBLE library.

Connections

• TXD: connected to a MIDI 5-pin DIN output connector (with series resistor, possibly through a buffer)
• RXD: connected to a MIDI 5-pin DIN input connector (with an optocoupler)

See https://midi.org/specifications/midi-transports-specifications/5-pin-din-electrical-specs for the schematic, optocoupler models and resistor values.

Behavior

• The Arduino will advertise itself as a Bluetooth Low Energy MIDI device with the name MIDI Adapter.
• When you connect to the Arduino using your phone or computer, the built-in LED turns on to indicate that the connection was successful.
• Any MIDI messages sent to the Arduino over BLE are sent out to the 5-pin DIN output connector.
• Any MIDI messages sent to the Arduino through the 5-pin DIN input connector are sent over BLE.

See also

MIDI over BLE

MIDI Tutorial

Written by PieterP, 2024-01-21
https://github.com/tttapa/Control-Surface

 
#include <Control_Surface.h>
#include <MIDI_Interfaces/BluetoothMIDI_Interface.hpp>
 
// Instantiate a MIDI over BLE interface
BluetoothMIDI_Interface midi_ble;
// Instantiate a 5-pin DIN MIDI interface (on the TX and RX pins of Serial1)
HardwareSerialMIDI_Interface midi_ser {Serial1};
// Instantiate the pipe to connect the two interfaces
BidirectionalMIDI_Pipe pipes;
 
void setup() {
  // Change the name of the BLE device (must be done before initializing it)
  midi_ble.setName("MIDI Adapter");
  // Do not require pairing or encryption
  midi_ble.requireEncryption(false);
  // Manually route MIDI input from the serial interface to the BLE interface,
  // and the MIDI input from the BLE interface to the serial interface
  midi_ser | pipes | midi_ble;
  // Initialize the MIDI interfaces
  MIDI_Interface::beginAll();
  // Initialize the built-in LED
  pinMode(LED_BUILTIN, OUTPUT);
}
 
void loop() {
  // Continuously poll all interfaces and route the traffic between them
  MIDI_Interface::updateAll();
  // Display the connection status using the built-in LED
  digitalWrite(LED_BUILTIN, midi_ble.isConnected() ? HIGH : LOW);
}