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2.1.3 Touch Switch Module¶
Introduction¶
In this project, you will learn about touch switch module. It can replace the traditional kinds of switch with these advantages: convenient operation, fine touch sense, precise control and least mechanical wear.
Required Components¶
In this project, we need the following components.
It’s definitely convenient to buy a whole kit, here’s the link:
Name |
ITEMS IN THIS KIT |
LINK |
---|---|---|
Raphael Kit |
337 |
You can also buy them separately from the links below.
COMPONENT INTRODUCTION |
PURCHASE LINK |
---|---|
Schematic Diagram¶
Experimental Procedures¶
Step 1:: Build the circuit.
Step 2: Change directory.
cd ~/raphael-kit/python/
Step 3: Run.
sudo python3 2.1.3_TouchSwitch.py
While the code is running, the red LED lights up; when you tap on the touch switch module, the yellow LED turns on.
Code
Note
You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like raphael-kit/python
. After modifying the code, you can run it directly to see the effect.
#!/usr/bin/env python3
import RPi.GPIO as GPIO
import time
# Set #17 as touch switch pin, #22 as led1 pin, #27 as led2 pin
touchPin = 17
led1Pin = 22
led2Pin = 27
# Define a setup function for some setup
def setup():
# Set the GPIO modes to BCM Numbering
GPIO.setmode(GPIO.BCM)
# Set touchPin input
# Set ledPin output,
# and initial level to High(3.3v)
GPIO.setup(touchPin, GPIO.IN)
GPIO.setup(led1Pin, GPIO.OUT, initial=GPIO.HIGH)
GPIO.setup(led2Pin, GPIO.OUT, initial=GPIO.HIGH)
# Define a main function for main process
def main():
while True:
# touch switch high, led1 on
if GPIO.input(touchPin) == 1:
print ('You touch it!')
GPIO.output(led1Pin, GPIO.LOW)
GPIO.output(led2Pin, GPIO.HIGH)
# touch switch low, led2 on
if GPIO.input(touchPin) == 0:
GPIO.output(led2Pin, GPIO.LOW)
GPIO.output(led1Pin, GPIO.HIGH)
time.sleep(0.5)
# Define a destroy function for clean up everything after
# the script finished
def destroy():
# Turn off LED
GPIO.output(led1Pin, GPIO.HIGH)
GPIO.output(led2Pin, GPIO.HIGH)
# Release resource
GPIO.cleanup()
# If run this script directly, do:
if __name__ == '__main__':
setup()
try:
main()
# When 'Ctrl+C' is pressed, the program
# destroy() will be executed.
except KeyboardInterrupt:
destroy()
Code Explanation
touchPin = 17
led1Pin = 22
led2Pin = 27
touchPin
, led1Pin
and led2Pin
connects to the GPIO17, GPIO22 and GPIO27,
namely BCM17, BCM22 and BCM27.
GPIO.setmode(GPIO.BCM)
GPIO.setup(touchPin, GPIO.IN)
GPIO.setup(led1Pin, GPIO.OUT, initial=GPIO.HIGH)
GPIO.setup(led2Pin, GPIO.OUT, initial=GPIO.HIGH)
Set the GPIO modes to BCM Numbering. Set led1Pin
, led2Pin
to output mode
and initial their level to High (3.3v).
# touch switch high, led1 on
if GPIO.input(touchPin) == 1:
print ('You touch it!')
GPIO.output(led1Pin, GPIO.LOW)
GPIO.output(led2Pin, GPIO.HIGH)
# touch switch low, led2 on
if GPIO.input(touchPin) == 0:
GPIO.output(led2Pin, GPIO.LOW)
GPIO.output(led1Pin, GPIO.HIGH)
When you tap on the touch switch module, touchPin
is high, led1 will light up and print "You touch it!". When touchPin is low, led2 will light up.