capacitive pin touch button (No hardware button)

[GigaJunky]

Ever need to detect a button, but don't want to wire one up or solder to the board.
Well the micro controllers can detect voltage from your fingers when you touch the analog pins!

here the code on a Raspberry Pi Pico.. should work with others:

# capacitive pin touch button by BitJunky 2024-03-02
# detects touching pin GP26_A0 with counter to prevent false postives
# led will light when touch has good contact
# micro python version, tested on a r-pi pico

from machine import Pin, ADC
import time

led = Pin(25, Pin.OUT)
pot = ADC(Pin(26))
count = 0
  
while True:
    A0_value = pot.read_u16()
    pressed = A0_value > 13000
    
    if pressed:
        led.on()
        count=count+1
    else:
        led.off()
        count=0
    
    print(A0_value, pressed, count)
    
    if count > 10:
        print('You touched it!')
        
        for x in range(20): #blink led to confirm
          led.toggle()
          time.sleep(0.1)
        
        time.sleep(1)
    
    time.sleep(0.1)
    

and for circuit python here:

# capacitive pin touch button by BitJunky 2024-03-02
# detects touching pin GP26_A0 with counter to prevent false postives
# led will light when touch has good contact
# circuit python version,  tested on a r-pi pico

import time
import board
import digitalio
from analogio import AnalogIn

A0 = AnalogIn(board.A0)

led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT


while True:
    
    pressed = A0.value > 13000
    led.value = pressed
    
    count = count+1 if pressed else 0
    
    print(A0.value, pressed, count)
    
    if count > 10:
        print('You touched it!')
        
        for x in range(20): #blink led to confirm
          led.value = not led.value
          time.sleep(0.1)
        
        time.sleep(1)
    
    time.sleep(0.1)
    

[davefes]

See this for the "fun" I had with the run pin;
https://github.com/orgs/micropython/discussions/12668
pin16 seemed to be the only other pin that was as sensitive.