sort-of-OT: DIY touchpad
I'd like to get in touch with any Maxers doing DIY Arduino-DMI stuff; I'm trying to identify suitable sensors for a force-sensing touchpad (X-Y-Z axes), circa 20x30cm. Apologies for off topic-ness of post, but I'm not getting much response via sites like Instructables and Make.
thanks all
Brendan
If you want each 'point' on your touchpad to be sensitive in all three axes, it might become rather expensive as you increase the number of sensors. Do you know the Eigenlabs Eigenharp? Each key is basically an xyz force sensor, and that makes it a costly affair (see http://www.eigenlabs.com/wiki/What_is_so_special_about_the_keys/).
Another approach would be to make a normal touchpad for example using IR light and a camera (Reactable Style), or one using one of those add-on films that can be used to add touch sensitivity to a regular screen, or an array of capacitative sensors. And then add one or more force sensitive resistors: (http://www.sparkfun.com/search/results?term=force+sensitive+resistor&what=products).
In all cases except the camera-based verion, there is some logic needed to interface everything with Max that goes beyond the capabilities of an Arduino.
The force sensors can be directly connected to the analog inputs of an Arduino. Capacitative sensors need some field-generating-and-sensing IC, as explained here: http://www.analog.com/library/analogdialogue/archives/40-10/cap_sensors.html
Hope it helps.
Thanks EMV, this will help me make a more informed decision, but I guess the only real way to come to a decision is to build-test-build-test. I have several FSRs so I might go with those;
"those add-on films": any pointers to those for me? I was going to buy a touchscreen overlay
then hack it somehow, to get signals into the arduino, and add some FSRs at the four corners/edges.
Does this sound viable?
Thanks again
Brendan
The 4 wires on the resistive touchscreen overlays are V+, x, y, ground, usually (consult the documentation for whatever one you have). This is pretty easy to interface with a couple of Arduino analog pins. A cheap DIY FSR can also be made by sandwiching a layer of Velostat (carbon-impregnated plastic sheeting) between 2 conductive layers. Have fun!
Ok
there's two people who'll need a mention in my thesis!
thanks
Brendan
would love to see what you come up with, that sounds like an awesome interface!
...as a key element of a PhD thesis I don't want to give too much away, but the emphasis is on accessible creative interaction for physically disabled musicians. Look at the interfaces/instruments Roger Linn and Max Matthews are using in this video:
Brendan