todbot/touchytouch

Capacitive sense (capsense) touch Arduino library that mimics how CircuitPython touchio work

TouchyTouch

Capacitive sense touch Arduino library that mimics how CircuitPython touchio works.

This library emulates how the CircuitPython touchio library implements capacitive touch sensing. It also includes basic button debouncing.

It is based on the CircuitPython "touchio" code at: https://github.com/adafruit/circuitpython/blob/main/shared-module/touchio/TouchIn.c The touchio code is not platform-specific, but does require a 1M pull-down resistor.

Thus the TouchyTouch Arduino library is also not platform-specific and also requires a pull-down resistor.

How it works:

From the touchio C code:

// This is a capacitive touch sensing routine using a single digital
// pin.  The pin should be connected to the sensing pad, and to ground
// via a 1Mohm or thereabout drain resistor.  When a reading is taken,
// the pin's capacitance is charged by setting it to a digital output
// 'high' for a few microseconds, and then it is changed to a high
// impedance input.  We measure how long it takes to discharge through
// the resistor (around 50us), using a busy-waiting loop, and average
// over N_SAMPLES cycles to reduce the effects of noise.