Are you feeling Red, Green or Blue? Just orient this convex hexahedral cage to illumunate the color of your choice. The lights flicker when you bang the table it is on (presumably the ball in the tilt switch bounces).

This controller demonstrates how most resistive touch screen systems can be modified to provide independent sensing of two positions on the surface. A single pressure measurement is also provided with a third sensing layer. A pair of SlideWide sensors (http://infusionsystems.com) are stuck to each other at right angles.

Illuminated button array music controllers have a long history. I was fortunate to meet the late great, Salvatore Martirano who pioneered the construction of large button array music synthesizers.

This controller with no direct antecedents is made by draping conductive stretchable fabric over a cereal bowl creating a curve similar to the famous one called the witch [sic] of Agnesi. Resistive strips around the bowl are shorted out by the fabric and the varying resistances are measured and sent as OSC messages via USB control software on a host computer - typically resonance model sounds in Max/MSP.

The fabric is stretched in an embroidery hoop and draped over an inverted circular bowl. A piece of conductive plastic cut in a special shape forms a corolla on the surface of the bowl. The tips of each petal are folded inside the bowl and taped with conducting-adhesive copper tape or fabric tape. The microcontroller board measures the electrical resistances of these petals from their tip to a common center established with a gold-plated fabric ring at the flat of the bowl. As the conductive stretchable fabric (the “calyx” to complete the flower analogy) is displaced towards the bowl it shorts out different lengths of each conductive plastic petal.

The result is a circular array of nearly mass-less displacement sensors. The gesture-to-displacement relationship changes according to distance from the center of the bowl (variable “gearing)”. This allows for several different playing styles.

One style, similar to hand drum technique, involves tapping the fabric surface directly onto the bowl with the fingers of one hand and leaning towards the other side of the bowl with the palm. Another style involves both hands interacting from the outer hoop towards and around the base of the bowl.

You may also put it on the ground and use it as multiple foot “pedals”.

A second version increases the number of fabric pressure sensors on the base board from 2 to 16.

An important point about the Tablo is that the drape sensing allows both very delicate light touch to be sensed along with very muscular or fast gestures when the fabric touches the piezoresistive strips. It is very hard with stacked position and pressure sensors to achieve this dynamic range so essential for compelling hand drum gestures.

It has been designed so that all the important sensing nodes are surrounded by grounded fabric to keep the noise down.

The hoop is easily removed so that the only moving part (the stretch fabric) can be replaced or washed.

A single pressure sensor is snuck into the top of the bowl.

There is lots of interesting potential math behind the shape of the bowl: spherical doesn’t work well, a catenary may yield a nice linear relationship between the finger position and sensed value, the “found object” bowl used is very good and almost linear.

You can scale this design up to support multiple people playing it if you can afford the fabric.

You can also build it in a linear/keyboard style instead of "in the round".

This example uses the recommended OSC SLIP wrapping for OSC serial messages. Attached is an example Max/MSP patch to display the OSC messages which represent the pin states, temperature and power supply voltages. You may need slipOSC from the CNMAT downloads page to unwrap the USB serial OSC. This is a simple introduction to building OSC messages. Yotam Mann built a complete library for Arduino that does the full OSC encoding available on github CNMAT.

Experimental surface sensing for fingerstyle players

I don't use the stock "official" Arduino boards for my work. The $18 teensy 2.0 is smaller than any of the stock Arduinos, has more A/D pins than any of them except the Mega, has more memory, more PWM pins, full speed USB serial support and has a more accurate crystal cock instead of a resonator. You can buy them from the designer ($18$16) or from Lady Ada ($20). Sketch loading and restart is much faster because of the high speed USB port.

The FTDI drivers aren't necessary with the Teensy and you can add the Teensyduino overlay to run your Arduino sketches.

This is not a vanity web site. I am tuning the design and content of the site to serve you, the visitor, with the fruits of my creative output which are tools and recipes for the most part.

I am in the middle of the first phase of site development, implementing best practices in web interaction using ajax, css, javascript and various drupal modules. During the second phase, to start in earnest next year, I will upload more content drawing equally froom my past work and ongoing projects.

I built this from a MusicMaker's kit. THe wood is mostly cherry with a spruce plywood soundboard.

A collection of power sources for e-textile and wearables projects.