Touchpad Foolery

[cheft]

Thought I'd post some information on my work with touchpads this last week as others may find some of this information useful. My friend gave me a non-working HP Pavilion. I wanted a touchpad in an Arduino project I have in mind. You can easily wire most touchpads to a PS/2 or Serial (9-pin), and even old school AT!

Removal can be a bitch. On the HP, it was secured by screws under the bezel and glue. I shot it with a hair dryer for 10 minutes to heat the glue and managed to pry it off with out harming anything. (You could also purchase one off ebay)

After I got it out I Googled every number on the back and discovered I was the proud owner of a Synaptics TM41PUZ307. Synaptics has a great resource for helping you determine the pinouts of many of their models HERE My Synaptics TM41PUZ307 wasn't on the list, but an internet search turned up this:

• pin5/6 = GND
• pin7/8 = CLK
• pin9/10 = DATA
• pin11/12 = +5V

I chose to wire to a PS/2 cable I salvaged from a broken keyboard to test if this was even gonna work. I used a razor blade to separate the flat cable into it's different connections and soldered to the cable. TIP: Use warm solder, if it's too hot you'll just melt the flat cable. I plugged it in the PS/2 port on my desktop quickly and the standard windows mouse driver worked just fine. Without installing any drivers, I was able to navigate the mouse, left click, and use the mouse scroll wheel. I mounted it on my keyboard for now. I tried installing the touchpad driver from HP's site, and the generic driver off Synaptics website, but neither found a device. I was hoping to be able to run Touchpad2Midi at least. I'll post here if I have any success.

Applications:

• There are a host of applications that will convert a PC mouse to a Midi device. You can find a list HERE
• To use with USB you'd need to buy (or make?) a 'USB to PS/2 Keyboard and Mouse Converter'. You could also solder into a wireless mouse.
• I plan on eventually using it in an Arduino project. Details on interfacing a trackpad to an Arduino can be found HERE See a project HERE

Use a multimeter to confirm what the pinout of the PS/2 cable is.
Your wire colors may differ, mine where as follows:

• pin1 = DATA = Red
• pin3 = GND = Grey
• pin4 = +5V = Brown
• pin5 = CLK = Yellow

Or, you can wire to a 9-pin Serial port old school mouse style. This is also nice idea to use on a desktop as a secondary mouse.

• pin4 = DATA
• pin5 = GND
• pin7 = CLK
• pin8 = +5V

*You could even wire to an AT keyboard.

I'd like to learn if there are other ways of decoding the mouse data to control X/Y coordinates. Can you convert the data to control two potentiometers at once an easier way then using an Arduino?

[BentoSan]

Nice work thanks for posting up the info

[Fatlimey]

Fantastic article. Great write up filled with valuable information for anyone who's looking to recreate your work. Color me impressed.

You asked if there's a way to use the mouse X/Y to control two MIDI controllers at once? Sure, I'm sure it's possible using HID to MIDI and software like Junxion can do exactly that translation for you.

http://www.steim.org/steim/junxion_v4.html

If your question was about converting the hardware stream directly without involving a microcontroller between the pad and the outputs, I'd say the answer is no. Not because it's impossible, just because the alternative, a custom digital-to-analog conversion circuit, would most likely be more expensive and have more parts than a single 8-pin ATtiny12 controllers, and do less.

You don't need an entire Arduino to do the job. You can do it much smaller and cheaper. Programmer and breadboard here: http://tinkerlog.com/2009/01/18/atti...board-headers/

[cheft]

I know I don't "need" the Arduino. My cousin says he can program a PIC chip to convert to analog. But I plan on using the Arduino for more than just the touchpad, my ultimate controller, if you will.

I used apps like Juxion for PC, in fact we have a large list collected in another thread here on DJTT. My problem with those apps is that they remove ALL functionality of the mouse when the app is enabled usually. Touchpad2Midi is cool because when it works properly, it leaves the mouse and only disables your trackpad. If I HAD to use it with a PC all the time, I probably use Bome's Midi Translator to set a 'modifier' to enable the mouse to act as a midi device, something like Caps Lock.

[CerebralExcretion]

Wondering if you made any more progress with this project?

Im in the process of building my dream midi controller, im using a snaptics trackpad powered by an arduino. It out puts x y values which i use to output midi cc comands. I initially tried using joysticks but found them to be hopeless at controlling filters as they cant reach the extream high and low frequencies.

[cheft]

No I haven't. Lack of funds. I hope to buy a new Arduino Mega. Did you see the project I was reference. He had code and instructions you can use. Pretty straightforward.

I have been using a GlovePie script to get the touchpad to work as a Midi Controller. It's a neat app in that it can differentiate between different mice. I can us it so when I press a key (Z) the touchpad turns into an x/y pad midi controller, and I still have mouse functionality with my USB mouse. This trick may even work on most laptops, as the touchpad is found as a PS/2 device on most laptops.

[CerebralExcretion]

=(, im using that track pad script to get the x y values. But that s a nice idea to have mouse functunality too, then i should never need to touch the laptop atall.

I have coded kaoss pad and kosilator type controls (got many of the functions from the manuals ) to control synths and effects in live. I started out with 4 trackpads but found one was plenty for my needs and means i have plenty of spare pins on the standard arduino for a huge lcd display, 20 infinate rotary knobs, arround 80 buttons, and more leds than you can shake a very large stick at. I cant wait to get it finished but getting all the measurements right for the face plate takes ages!

[mpetersen3]

I would like to either use a add a laptop touchpad to somewhere on my vci to use as a mouse, or to see if I could potentially use the touchpad on my nanopad and remap it through software to act as a mouse, any ideas if I could send the nanopad shit as HID and then map the touchpad as a mouse and use a miditranslator to ensure that the rest of the pad still works as normal?

Ed. We digiJays are so self conscious to try and avoid touching the laptop at all costs aren't we?

[CerebralExcretion]

Im not aware of any software that converts midi to hid so don't think you can use your nanopad, but if you follow cheft's instructions and the video bellow its ridiculously easy to convert a trackpad to a ps2 mouse (of course your laptop must have a ps2 port for this to work).

http://www.metacafe.com/watch/990407..._pad_ps2_hack/

[cheft]

GlovePIE will convert midi to HID. And I bet Bome's can.

I personally use my laptops touchpad as a midi controller, but also have a USB Logitech MarbleMouse. Sometimes you just need a mouse dammit!