The 5$ Karduinoss Pad

Intro: The 5$ Karduinoss Pad

So, looking at these Kaoss pads and alike hardware, I found that there is hardly any point in this device being so expensive, when you just want to use it as MIDI controller.

Going through my parts bin, I found a Synaptics touchpad from an old laptop and figured this should just work as a replacement.

Ok, when I say 5$, i mean really cheap. Clearly a loose arduino is already 20-25 USD (but you can replace it with just a bare ATMEGA168 chip for ~2 USD) , and this touchpad would probably cost you some money aswell, when you are not able to salvage it from an old laptop.

WARNING: the Kaoss pads and similar hardware all have built-in audio outputs, this project does not ...

STEP 1: Find the Signals

After some brief google (and going through the mostly pointless documentation) I found this website that helped me a great deal :

http://sparktronics.blogspot.com/2008/05/synaptics-t1004-based-touchpad-to-ps2.html

This website had the picture you see here. From this I figured out which of the testpoints on the board (wow, many!) where connected to these 3 pins. (see second picture).

I'm not quite sure if the T1001 controller is similar in pin-out to this controller, but the signals shouldn't be too hard to find if you know what to look for.

STEP 2: Soldering to the Touch-pad

Well, this is simple enough, bring out the points you have found :D

The main trick is to use pretinned wires and first get a small island of solder on the testpoints you have found. Be careful to not put too much heat on the touch-pad, the copper can very easily get  loose from the pad by overheating.

For ground I soldered to the big square connection (see also the pin-out image), but there are many more places where you can get ground signal.

After this step, you probably want to secure your soldering with some hot glue or similar product for strain relief.

STEP 3: Interfacing to the Arduino.

As you now have a touch-pad with wires attached to it, lets look into getting values from it.

The available ps2 libraries for arduino naturally work as a mouse and allow for mouse type input, if you're into such a thing ;)

Below you will find a karduinoss.pde sketch for the arduino based on the ps2 library available on http://www.arduino.cc/playground/ComponentLib/Ps2mouse which will initialize the touch-pad as an absolute xy controller with about ~4000 steps side to side.

The code does some auto-calibration based on the values it gets, and maps the x, y and z values to MIDI controller changes through the use of ttymidi available on http://www.varal.org/ttymidi/.

The karduinoss.pde sketch assumes an LED is connected to pin 3 ,the touch-pad clock on pin 13 and the touch-pad data on pin 12.

STEP 4: Package It Up

Well, let your imagination run wild :D

I save plastic containers from random stuff to use for projects like this.

The packaging I made clearly is not the most solid possible, but I'm sure it will hold for a couple of performances before I need to think about a new case.

STEP 5: Use It!

Now is the time to actually use your newly made karduinoss pad for some nice midi action :)

Below you see a screenshot of 'alsa modular synth' (which you can find on http://alsamodular.sourceforge.net/ )

But of course you are free to use it in any program that supports midi input :D

I hope everybody enjoyed this instructable and will find inspiration to make his/her own midi controller now!

Comments

[itstimacious]

Question for the OP. Is it possible to use a touchscreen from an old smartphone instead of a TouchPad so it can be programmed to have a particle tracer running so when you touch it bits of LED particles rush to your hand?

I ask because I have a few old smartphones with intact screens that I'd like to salvage, and I have an idea for a fantasy based guitar that I want to include a karduinoss pad into.

[lmeucchi]

Cuando quiero descargar el codigo, me descarga este archivo "FDAV83QG8XPHU9U.tmp"

[lgh1]

ineed WProgram.h plizz

[trogper]

and photo
https://dl.dropboxusercontent.com/u/4533932/IMGRES/synTP.jpg

[trogper]

I've got Synaptics touchpad prom older HP notebook
I connected it to arduino, loaded your program, but it doesn't do anything
the chip has T22, T11, T10 connected to same pins as your.
old PS/2 mouse worked with some program I found.
reply to [e-mail]

[TheLegoDJ]

Any way this could be implemented without the us of an arduino? As in a Joystick to midi connection setting up an wired xbox controller or any other joystick?

[fetchtables]

Do you think this will work with a touchscreen? I'm thinking of putting an led array under one so it looks like the Kaoss pads.

[sukoa]

I don´t fully understand it, is this a stand alone synth or does it requieres from a computer to work as a synth?
Thanks!

[xenomorph150]

i got the synaptics pad soldered successfully and can use it as ps/2 mouse (Standalone, got none arduino at the moment) - but I want to ask how I can interface the "ready" device (pad + arduino + your code on the arduino) with windows 7 as midi device? is there an windows port for ttymidi or is there another way to attach this thing as midi device in win 7? thanks

[buZztiaan]

There doesn't seem to be a ttymidi alternative for windows (that I can find ...), but hackaday.com had a link to this application that will let you use a touchpad as a MIDI controller through a normal ps2 connection : http://www.livelab.dk/touchpad2midi.php Also, I'm looking into replacing the arduino with a teensy, to get 'real' usbmidi, which should work without driver in every operating system.

[crapflinger]

isn't this more of a "possible way to hook a laptop touch pad to an arduino" kind of thing? i don't see anything about how to actually use it as a midi controllor or as a kaos pad...

there aren't really any instructions on how to do much of anything here...maybe you should do this as a forum topic to get some suggestions on what you're doing untill you've got enough done to make a full instructible

[frollard]

Agreed - it needs a little more stuffing to be a full instructable per its title.

*I do think this is really neat, never thought before how to interface with one of these...

[buZztiaan]

and it will, as soon as I have some finished programming to post ;)

[crapflinger]

well...i guess the deal is that you don't have to press publish on an ible if it's not finished....it doesn't add any benefit to publish something that's unfinished (or at least not mostly finished)...and you end up with a lot of comments like you've gotten so far (i.e. why'd you publish this if it's not finished)

[Bongmaster]

nice :)
i got a whole bunch of touchpads i wanna put to use XD