MIDI Keyboard control

Question

I am relatively new to Arduino and I am looking to implement a simple system that uses a MIDI keyboard to

(i) detect key presses (via MIDI messages) from the keyboard

(ii) store the information of the MIDI messages (note pressed, velocity)

(iii) Light up LEDS on the keyboard based on what key was pressed

I am currently in the planning stage and I am considering using an Arduino Mega. I have two issues I am not sure about:

(i) My keyboard only has a Male USB A to Male USB B connection with the former connecting to the computer and the latter to the keyboard. So far in my search, I have seen that all Arduino-MIDI projects require a 5 pin MIDI cable to interface with the Arduino using the circuit in this webpage (https://www.instructables.com/id/Send-and-Receive-MIDI-with-Arduino/). Is there any way to detect MIDI messages that does not require the additional circuit and just uses the USB cable?

(ii) Although in theory control of the LEDs should be easy in the program, I am concerned that the delays in the serial communication and hardware interrupts would make it difficult to simultaneously receive the MIDI messages and control the LEDs.

One way I thought of avoiding these problems is to use MATLAB MIDI package (https://uk.mathworks.com/help/audio/ug/midi-device-interface.html#mw_80dc54f4-867c-43c0-a159-e56ee62ec4ab) to interface with the MIDI device and use the MATLAB Arduino package to control the Arduino. I am not sure, however, if MATLAB is suboptimal compared to the standard Arduino IDE.

This is my first question in Arduino StackExchange (or any StackExchange site), so I appreciate the answers and feedback on my question.

Answer 1

Is there any way to detect MIDI messages that does not require the additional circuit and just uses the USB cable?

You could probably do it with a "USB Host Shield", though I have no experience of them and don't know if they can handle MIDI - you'll have to research this.

Although in theory control of the LEDs should be easy in the program, I am concerned that the delays in the serial communication and hardware interrupts would make it difficult to simultaneously receive the MIDI messages and control the LEDs.

Highly unlikely. You'd have to be doing something very wrong to make it so slow to respond that you'd see any delay.

I am not sure, however, if MATLAB is suboptimal compared to the standard Arduino IDE.

I cannot comment, I have never used MATLAB. If you don't use a USB Host Shield then you will certainly require something that runs on a PC to forward the MIDI information over serial. Whether you create that in MATLAB or some other programming language is neither here nor there as far as the Arduino is concerned - you'll still need to program the Arduino itself, and that can be done in the IDE and still use MATLAB for the PC portion of your setup.

Answer 2

• I don't have experience with USB MIDI, but I'm (almost) sure it should work with a shield (as Majenko already writes).
• I have experience with the following library. I used it for normal (DIN5) MIDI, not via USB, but it seems to support USB too: https://github.com/FortySevenEffects/arduino_midi_library This library is interrupt based, try to keep the interrupts as short as possible, you can do the processing of the MIDI messages in the main function, together with driving the LEDs.
• I created a (temporary) USB merger which worked quite well, so yes, with a Mega it's easy to use 3 (or 4) MIDI channels, using DIN5. It's more than fast enough. MIDI is just 31.250 baud.
• I found it was very annoying to use the only UART of an Arduino Uno to use for both MIDI and debugging/uploading, so it's easier to use 3 UARTs from the Mega, and when your program works, use the main RX/TX for MIDI too (make it flexible).
• In case you think about use the software serial: forget about it, at least for reading MIDI.