About the Capacitive Sensing Touch Pad of the Tickle

The surface of the Tickle is a continuous capacitive sensing touch pad with 8 bit resolution in both axis. It has a hexagon tile print on it. To determine in which hexagon a touch occurred is calculated from the absolute x and y positions. Capacitive touch only works with objects which can induce capacitance like things that contain a lot of water such as fingers (or sausages). That means that fingernails, drumsticks or a bow will not be registered as a touch event.
You can use this fact to your advantage by incorporating it into your playing-technique. Try applying a bow to the edge on the side of the Tickle or hitting it with an object while simultaneously holding a finger on the respective pad to select a pitch or sound.

Single touch

The touch pad does not handle multi-touch, so gestures with multiple fingers are not possible. If you touch the tickle with multiple fingers it may jump back and forth between the two points and may even generate a third or fourth “ghost” touch point

Speed before sensitivity

To allow for fast playing of complex rhythmical patters with high precision in the timing, little jitter and low latency are necessary. The capacitance of the surface is measured in under 5 ms polling rate (~ 250 Hz). In order to achieve this fast scanning we had to compromise on the touch sensitivity, so fingernail touches or touches with very small contact area aren’t registered. If you experience problems with not detected touches, try increasing the touch surface. This might mean to change from an ideal piano finger posture to a more sloppy stretched-out finger posture.

Sync with audio signal

The touch data should never lag behind the audio data. We buffer the audio (add extra latency) to make sure it always comes after the touch data. That said, with the Class Compliant setup this is a bit out of our control, meaning it is possible that on some systems the users still might experience it that way if their MIDI transmission somehow lags in an exceptional manner.

Grounding

There are some known issues with grounding. If your body is statically charged and discharge happens into the Tickle when touching it (this may happen when you wear a wool jumper over a polyester shirt) it is possible that the spike of electricity will make the Tickle reboot and go to CV mode.
If the ground level changes in your local power supply, the sensitivity of the Tickle capacitive sensing surface can vary, either becoming so sensitive that even if it isn’t touched there are touches detected (and thus there are no more note-off events, just erratic gestures), or it doesn’t detect touches any more at all. In our office this happens if another computer in the same room is going into sleep mode. To resolve the issue unplug and plug in again.

Also please read the general advice.

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