Tod Kurt's "picoslidertoy" Delivers 25 Capacitive Touch Inputs to a Raspberry Pi Pico — with Sliders
Clever board uses trios of capacitive touch points to deliver "analog" swipe sensing.
Embedded developer and self-described "multi geek" Tod Kurt has designed a capacitive touch-sensitive control surface for the Raspberry Pi Pico, offering 25 individual sensors for both simple buttons and more advanced linear and rotary slide controls: the picoslidertoy.
"I wanted a way to experiment with linear and rotary touch sliders," Kurt explains of his project's origin. "I made some touchwheels to give away for Hackaday Supercon 2023 and they were popular. I wanted a larger playground for experimenting with these controls. The picoslidertoy can be a USB MIDI control surface, a USB Macropad keyboard with 'analog' controls, or even a USB gamepad."
Designed for use with a Raspberry Pi Pico and using up 25 of the available general-purpose input/output (GPIO) pins available on the board, the picoslidertoy delivers three different types of touch-sensitive capacitive input controls. The simplest of these are nine buttons, but these are joined by a pair of rotary sliders and three linear sliders — capable of tracking the movement of a finger in a circle or a line respectively, rather than just a single point of contact.
"The 25 capacitive touch sensors are read directly by the [Raspberry Pi] Pico, either via CircuitPython's touchio library or the TouchyTouch Arduino library. No external touch chip needed," Kurt explains. "I think that's really cool! Getting an 'analog' value out of the three touch sensors that make up a linear or rotary touch slider is fairly simple but there are some tricks I'm developing to make the values stable."
The picoslidertoy is available to buy on buy on Kurt's Tindie store, starting at $11 for a kit or $16 fully-assembled but lacking a Raspberry Pi; a $36 bundle offers a fully-assembled variant with a Raspberry Pi Pico clone board and an SSD1306-based I2C OLED fitted.
The project's design files, source code, and 3D print files for an enclosure as available on GitHub under the GNU General Public License 3.