Demo analog touch value using raw_filter and filtering with CircuitPython touchio

touch_analog_code.py

# touch_analog_code.py -- demo analog touch value using raw_filter and filtering
# 21 Jul 2022 - @todbot / Tod Kurt
# A simpler version of concept in "Trinkey Theramin" (sic)
#  https://gist.github.com/todbot/50c0f388add780f9d75489e0bebad96c

import time
import board
import touchio

touch_pin = touchio.TouchIn(board.A3)  # can be almost any pin on most boards

touch_baseline = touch_pin.raw_value * 1.02  # 2% over 

def smooth(val, last_val, smoothing=0.90):
     return (smoothing * last_val) + (1-smoothing) * val

touch_val = 0
while True:
    touch_new = touch_pin.raw_value - touch_baseline
    touch_new = min(max(touch_new, 0),255) # clamp between 0-255
    touch_val = smooth(touch_new, touch_val, smoothing=0.93) # smooth it
    print("touch: %3d" % touch_val)
    time.sleep(0.01)