Arcade Button MIDI Controller

Having a hardware interface to your favourite music / DJ / VJ software can really open up doors in your creativity. The most widespread form of hardware control to your PC for such applications is a MIDI based controller.

A MIDI controller can send and receive MIDI messages to your PC, allowing direct control of your software. Not only that, but the controls can generally be mapped to anything your like. So what might be a volume fader for one person can be an effect filter for another.

This article will describe how to build and program a custom arcade button MIDI controller, while trying to keep the price below $100. It is aimed at electronics and programming novices.

Step 1 What You'll Need

Below is a list of components used to create the MIDI controller. The cost for this project is based on the components needed for the MIDI controller. Other tools such as a soldering iron or a power drill, or common components such as solder and wire aren't included in the final cost. Tools which I did have to purchase are marking with italics , and their price is shown. All prices are in AUD except where indicated.

Required Components
1 x DFRduino (cheaper Arduino clone) $28.80
1 x USB cable (A to B connector, like that on a printer) $3.95
1 x Plastic enclosure $15.75
12 x Sanwa 24mm arcade buttons $26.28 (USD)
4 x 10k linear potentiometer $4.88
4 x Pot knobs $3.80
2 x 10k linear sliding potentiometer $7.54
2 x Slider knobs $2.04
5 x 10mm M3 nylon threaded spacers $2.00 (I got a bag of 25 for $9.95)
4 x 16mm countersunk M3 screws $1.00
3 x 4mm M2 self tapping screws $0.75
1 x 4.7 kΩ resistor $0.10
4 x stick on rubber feet $2.00

Total $98.89

All of the above can be found at most online electronics stores (I use the excellent Little Bird Electronics ), except for the Sanwa arcade buttons which can be found at arcade replacement parts stores, or from DJ TechTools . It pays to purchase one or two spare buttons and perhaps a spare potentiometer in the event that the part is faulty or you accidentally make it faulty.

Required Tools
Soldering iron
Solder
Wire stripper
Small gauge stranded wire (22 AWG), preferably in three or more different colours
About 1m of 2.5mm heat shrink
Power drill or drill press
Drill bits (2mm, 3mm, 7mm, and 11mm)
Spade bit (24mm) $12.49
Countersinking bit
10mm hexagonal wrench or spanner
Needle-nose pliers
Small riffler files $15 for pack of 10
Regular file
Phillips-head screwdriver 

Comments

[chaoszerom]

I'm planning on making a midi controller such as this one, and since I'm in Aus, Little Bird is a good place for components. However, you mentioned something about the datasheet being incorrect about the lengths for the slide potentiometers. Is that still right, or? The datasheet says that the slide length is 60mm, and the total is ~88mm.

[chaoszerom]

The link on the instructable is actually dead, so here's a current one: http://littlebirdelectronics.com/products/slide-potentiometer-10k

I'd say they're the same, but I could be wrong

[fraganator]

The datasheet for the slider looks to have been updated, and the dimensions match up with the sliders I have. Also check out the datasheet on SparkFun's site for the same slider: http://www.sparkfun.com/products/9119

Note the travel length is marked as 60mm, but for the groove of the slider you'll want a 5mm gap on either side of the travel to accommodate the slide lever.

[chaoszerom]

Thanks for that! I've ordered all my parts, and should get them in a week or two

[apefive]

will it works with Atmega32u4 Breakout Board w/ Arduino Leonardo bootloader ...using the teensy configuration?

thanks!

[apefive]

here it is

[fraganator]

As far as I know you should be able to do this. I'm not sure of the exact details for doing it through the Arduino IDE, but presumably you'd need to create a new hardware profile which mimics the teensy, but has the upload protocol set to Leonardo.

Another way would be to compile the teensy code as normal, but then flash the hex file using an In-System Programmer directly to the chip, and not having a bootloader at all. That said, a bootloader makes things much easier, so use a bootloader if you can!

[apefive]

ciao!

i uploaded correctly your sketch on the Atmega32u4 Breakout Board and set it as midi device. (it seems it works).
this board is identical to the teensy, only that the pins are in different positions.

this is my project using 16 pushbutton and 9 potentiometer 1MΩ.
what you think about? will i have to change somethings on your sketch?

thanks!!

[apefive]

EDIT 16 pushbuttons and 9 potentiometers 1 mega ohm.

[fraganator]

Hi apefive,

The design looks good. You will have to tweak a few lines of the sketch to match the number of analogue and digital inputs, and the pins to which they're connected.

The code you'll need to update is on lines 129, 131, 173 and 186. Change NUM_DI to 16 and NUM_AI to 9. I'll leave the pin mapping changes to you :) Good luck!

One more thing - the ATmega32u4 datasheet (section 24.7.1) mentions the input impedance (resistance) recommended for the analogue to digital converter is no more than 10kOhms. Beyond that, the time it takes to convert the analogue signal into a digital one may take longer.

This probably won't be a problem with the 1MOhm pots as they won't be moving at super high speeds. If you do see delayed or lagging behaviour of the sketch with all of the pots connected, this may be the cause.

Disclaimer: I've never used anything higher than 10kOhm pots with an ATmega, so I have no actual experience here. I'm just quoting the datasheet!

[apefive]

hi, thanks for you reply!

i changed 129 and 131 lines, and:

#elif defined(TEENSY_2)
#define DIGITAL_PIN_ORDER 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
#elif defined(TEENSY_2)
#define ANALOGUE_PIN_ORDER 0, 1, 2, 3, 4, 5, 6, 7, 8

i have i strange issue too: when i upload your code (both on Atmega32u4 Breakout Board and on teensy 2) the boards send midi message without any pin connected and any activity (only usb connected). (they send chan16 ; controller 20 / 21. this sending is intermittent.)

thanks

[fraganator]

The intermittent MIDI messages you're seeing is most likely the result of floating analogue inputs.

When nothing is connected to the analogue pin, it doesn't have a defined electrical value. In other words it's not being pulled in any particular direction, and is considered floating. This floating value can change at any time due to any number of factors.

To guarantee the input isn't floating, it needs to be tied to an electrical value, usually ground. So if a pot isn't connected to the pin, the pin should be connected to ground.

Alternatively you can remove unused analogue inputs from the sketch to ignore their floating values.

[ith3be4r]

Hey!
Thanks a lot for this instructable, I'm just having 1 issue.

I have an Arduino Uno and I've connected/wired everything correctly. I uploaded the Jan 2012 version of the code, which was fine, but whenever I run the device the TX and RX serials aren't operating. I have not altered any of the parts or changed any of the code, i'm just not getting any serial reads from my arduino. Do you have any idea why this would be? I've tried a bunch of Arduino's official troubleshooting guides and nothings working.

Thanks for any help,
Cheers.

[ith3be4r]

UPDATE:
Whenever I press a button or use the faders/knobs the TX Serial light comes on the Arduino and in the Midi Serial Converter the RX Serial light lights up. I thought this might have been a solution but when I go to map the controller to Ableton Live it doesn't respond to any of my input.

[akshay30]

Hi, I want to make electronic drum set using your technique, & it should be velocity sensitive.

http://www.youtube.com/watch?v=WJrO9VYEoGQ

I did research on the net found the pressure sensitive sensors. i.e. piezo sensor

I bought arduino and followed your instructions.

It's working now
but piezo sensor not working like pressure sensor.
Its working, only when i connect ground and any input (like button switch)
What is the solution for pressure sensitive piezo ?
Should I need to change in the programming or not?

Basically I want to make midi controller for computer
I want to use FPC VST in FL studio for my midi drums.

and other problem, there is only 12 digital inputs in arduino board
I want more. I need minimum 16 digital input.
Is there any way to convert analog input into digital?

[Snarkity]

There is an example file included with the Arduino IDE called "Knock" that gets a value from a piezo. http://arduino.cc/en/Tutorial/Knock It is attached to an analog input rather than a digital. To get the value to a usable MIDI value, you'll have to scale it down with something like "piezoValue = map(piezoValue, 0, 1023, 0, 127);"

[liteoner]

Hi, nice job. What program did you use? I'm planning to make a similiar stuff with Teensy.

[AssAulterPT]

Hi, i'm using only 12 buttons. Do I need to change the code or can i still use the same?

And, on Serial MIDI Converter, the TX doesn't flash green. What's happening
Do you have any idea?

[caducotavio]

Greetings!
I'm a newbie, so please, be patient.
I've been trying to make my midi controller work, but I've come across two question: the first is about the incoming and outcoming ports to be used when under mac os 10.7?

About the sketch, I noticed there are conditions written specifically the arduino mega and others; mine, is uno. Do I have to change anything in order for the sketch to work correctly with my equipment?

Thanks in advance!

[fraganator]

I don't have access to OSX at the moment, so I can't comment on what the exact incoming and outgoing ports should be.

In terms of the sketch, it should run fine on the Uno without any modification. The conditions only come into effect when compiling for the Mega or Teensy.

[weber473]

Hi Fraganator!

I have my controller completely built just need to wire it up and program it. before I jump to the programming portion I had one more question!

A few weeks ago I found a tutorial on how to add instant gratification (multiple buttons pressed together creates a different effect than just one button). I apparently forgot to bookmark that tutorial :/
It came from the midifighter being able to have a certain effect if 1,2,3,4...etc buttons are pressed instead of the one individual button. But I do not believe it used the midifighter section of your program.

Do you know how to add this programming? Or does anyone by chance know where that tut. is?

Thanks again for your help!

James

[FreebirdRising]

I'm fairly certain that the MIDI Fighter combos are a mapping trick done through clever use of modifiers in Traktor, rather than creating a 5th midi note that triggers when multiple buttons are pressed.

[xanxor]

I can confirm this.
Look at the instant gratification layout .tsi and you can figure it out how to map the same type of deal yo your own controller.

[m3D!C]

i want to add lights next to the button just how the midi fighter lights up.would i wire it to the button or somewhere else?

[xanxor]

Wire it after the switch.

[hgarg2]

hi there!i want to know that can i upload any kind of beat in this controller??
and i just got little bit of confused from ur programming section info. can u plz upload a video of it or explain it briefly. im electronics student but the things u said i get confused on it. plz help.

[fraganator]

The controller simply sends MIDI messages to audio software running on a computer. The audio software then plays any sounds or beats based on the MIDI message. So the controller itself doesn't produce or play any beats.

Does that clear things up?

[mickartcan]

Hi , first thank a lot for this great tutorial .
I have just one question i'm total a newbie on electronic sorry.
the resistor is a 4.7 kohm but what watt i need ?
thank you

[fraganator]

A standard 1/4 watt resistor will be fine.

[mickartcan]

thank you i almost put a 1/2 pfiuuuu ;)

[weber473]

So if I went with the teensy all i would really have to do is wire it all up, plug it in and then no programming is needed other than in the dj software to map the buttons and pots to what i want them to do?

So exactly what number of buttons and pots could be used?

I also noticed they have a Teensy ++ http://www.pjrc.com/store/teensypp.html
which would just allow for more buttons and pots?

How hard or would it even be possible to put in some sort of jog wheel/ scratch wheel into this set up? Meaning is it possible to do with the teensy?

thanks for your prompt reply!

[fraganator]

Apologies for the not so prompt reply!

If you did go with the Teensy, you'd first have to load the sketch on to it from the Arduino software. From there all you'd need to do is plug it in and configure the MIDI mapping in your DJ software.

There are up to 12 analogue inputs and 13 digital IO for the Teensy 2.0 (you can have up to 25 digital IO, but you must use the analogue input pins). The Teensy++ 2.0 has 8 analogue inputs and 38 digital IO (or up to 46 digital IO when using the analogue pins). So it has more digital IO, but fewer analogue inputs.

Adding a jog wheel (aka a rotary encoder) to the setup would require some code changes to the sketch. I'm in the process of doing a complete rewrite of the source code, and hope to include more IO options such as jog wheels. It won't be done for a while yet though.

[FreebirdRising]

I'm also interested in using the Teensy++ for the additional ports... But even that is not good enough. :P How complex is it to add shift registers/multiplexors - code wise? Would it fundamentally change the design, or is it something that could be swapped in, or plugged in without having to totally rewrite the code?

Thanks for the great instructable! :)

[fraganator]

Adding shift registers shouldn't be too hard code wise. The Arduino library includes shiftIn() and shiftOut() functions. Check out the tutorial on shiftIn here.

You'd need to setup larger arrays for the button states coming in from the shift registers, and some logic to determine when you are reading from the on board IO and when you are reading from the shift registers.

Adding an analogue multiplexer would require similar changes, with larger arrays and on board/multiplexer logic.

So in short it's not a total rewrite, but does require a number of software and hardware changes.

[FreebirdRising]

Thank you for getting back to me. :)

I just learned about the Arduino Mega and Mega 2560... Would it be easier to use one of them over the Teensy++? Does your code already support it?

[fraganator]

The code should already support the Arduino Mega boards, though it's untested as I don't have a Mega board.

The advantage of the Teensy is that it can act as a true USB-MIDI device, unlike the Arduino which requires software on the PC to convert its serial messages to MIDI. The other advantage is that it's a fair bit cheaper.

That said, if you just want more I/O then the Mega should be fine and won't require any code changes.

[FreebirdRising]

Thanks. :)

In case you haven't seen it before: http://www.instructables.com/id/A-Framework-For-Making-Affordable-Stylish-Modula/

This instructable is another interesting one; I thought maybe you might be interested in looking at the code.

I'm really interested in having encoders... 8 of them! gah - I'm trying to make this so multi-purpose, I'm not sure I'm going overboard, but I've already got encoders ($30 worth!) given to me free, so I might as well work them in, right? :P

Anyway, I didn't know if seeing that code might help you out with your rewrite.

Cheers, and thanks again!

[weber473]

Not a problem. I did a lot of research since my question and basically figured out all of what you said minus the jog wheel. I actually went ahead and ordered all the parts to make a replica of the one you built. Having a custome built case from a coworker that has access to a 3d printer :)
I went ahead with the teensy 2.0 and will be putting it all together here in the next couple of weeks. I would be very interested to see what you come up with the jog wheel though. If you do figure that out it would be very highly appreciated if you contacted me about it. just let me know the best way you would like to contact me.
Ill let you know how my custom case and final product turns out. Thanks again for the replies and great work you have done here!

[bobthebanay]

i would like to use this thing to create my own controller. programing wise, what programing language is needed fo creating the script?

[fraganator]

The board used in this project is an Arduino, which has a development environment also called Arduino. It's basically a nice wrapper around the C++ programming language, along with the necessary AVR libraries and toolchains. You can download the development environment here.