[sdiy] Touchpad as CV controller

[Ullrich Peter]

Hi!


>On Tuesday 17 August 2010, Luís Marka wrote:
>> Inspired by a demo video of the Korg Electribe EMX-1, I was thinking
>> about the ribbon controller thing. I have a number of used notebook
>> touchpads lying around and was thinking about building a CV controller
>> using one of these. Idea is to give trig/gate outputs when the touchpad
>> is, well, touched, and X and Y information would translate as CV Outs,
>> with additional potentiometers for Offset and Scale.

>Notebook touchpads quite often have their controller built in and some of 
>those controllers were using a PS/2-like interface.  Newer pads might 
>directly communicate via USB.

Most notebook touchpads have a PS2 interface and a lot of them are made by Synaptics. I built a MSX mouse replacement touchpad for the use with Roland samplers with such touchpads.

Here is some information out of a PDF I made. The PDF and the ZIP files for the PS2 to MSX mouse converter (with PIC16f84 chip) can be loaded from the Files section of the Yahoo Group RolandSamplers or can be sent by me via private email:

"Notebook touchpad recycled for usage as Roland Sampler touchpad
             March 2006 by Peter Ullrich (www.ullrich.at.tt)

As I collected some notebooks over the years that were not really useful due to limited computing power or even damaged screens I wanted to have a look what parts of these notebooks could be used. The most interesting part for me was the touchpad or trackball unit built below the keyboard mechanics.
After disassembling I looked at the touchpad unit and found a sticker with a part number and a manufacturer on one chip: Synaptics.

So I startet a browser, entered www.synaptics.com found their webpage and after a short while I found the Synaptics touchpad interface guide manual as a PDF-file:
http://www.synaptics.com/decaf/utilities/ACF126.pdf 

They mention that most touchpads built into notebooks have the standard PS/2 interface. So I took a cable from an old PS/2 mouse, connected the right pins to the touchpad interface and checked it out on a PC: it is working! Fine!

So the next step was a test with the PS/2 to MSX mouse converter I built after Anikuns schematics. A nice little circuit built around a Microchip PIC16F84-10 that is working perfectly."

Ciao
Peter

http://come.to/synpro
http://go.to/datadial (synth addon)



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