Raspberry PI and capacitive sensor example

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In this example we will connect a capacitive sensor to a GPIO pin on our Raspberry PI, when we touch the sensor we will display a message to the user. A practical use may be a touch activated lamp.

This is the sensor we used which is low cost and available from multiple places

Capacitive Touch sensor
Capacitive Touch sensor

 

Here is a schematic representation, fairly straightforward

pi and cap sensor
pi and cap sensor

Lets look at the code, this is written in python and requires the RPi library to be installed, I recently downloaded NOOBs, installed RAspbian and python and this library were available by default.

Open the terminal and type in the following

sudo idle

Wait for IDLE to open,  then click File > New to open a new window. Or you can use CTRL + N.

Now enter the following code

import time
    import RPi.GPIO as GPIO
 
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(23, GPIO.IN)
 
 
    while True:
		pressed = GPIO.input(23)
		if padPressed:
			print "cap pressed"
 
    time.sleep(0.5)

Click File > Save when you are finished (Ctrl + S).

To run your program, click Run > Run (Ctrl + F5), your should output like the following

cap output
cap output

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