Adding a push-button and connecting it up the a GPIO port is as simple as writing a tiny pyhon script to initialize the IO port for input and utilizing a built-in pull-Up button. The Raspberry PI button is then capable to act as a Doorbell button.
After I connected the loudspeaker to the USB soundcard and soldered the USB connection from the Raspberry PI to the sound card I was then able to use alsaconfig to select it and then use:
1 | speaker-test -c2 -twav |
to actually hear some audio through the soundcard.
Now the next step was to connect GPIO port 17 to GND and use the built in bull-down-resistors to detect a button-press event.
Here is the push_button.py – python script which I use.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 | #!/usr/bin/python2.7import timeimport RPi.GPIO as GPIOimport subprocessGPIO.setmode(GPIO.BCM)GPIO.setup(17, GPIO.IN, pull_up_down=GPIO.PUD_UP)def my_callback(channel): subprocess.call ( "/root/bin/ding_dong.sh" )# add falling edge detection on a channel, ignoring further edges for 400ms for switch bounce handlingGPIO.add_event_detect(17, GPIO.FALLING, callback=my_callback, bouncetime=400)while True: # Loop once a day time.sleep(24*60*60)GPIO.cleanup() |
This script is straightforward and is simply waiting for a button press on GPIO pin 17 ( to GND ). The final loop is a forever loop with a one-day delay which will help keep the responsiveness of the Raspberry PI button at a good level. If during this time a button press was detected, then the ding_don.sh – script, which in turn plays a sound on the speaker.
I plugged it into /root/bin/push_button.py and made sure it is executable
1 2 3 | sudo mkdir /root/binsudo vi /root/bin/push_button.pysudo chmod +x /root/bin/push_button.py |
Below is the pin-out of the Raspberry PI Zero W.
GPIO ports
In this case I connected GPIO17 ( orange wire ) and GND ( blue wire ) ( PIN 11, and PIN 14 ) to the doorbell button.
Instead of packing all the functionality into one python script I decided to have python call a simple bash – script to do the actual work. Here is the ding_dong.sh script, which is called by the python script and also resides in /root/bin/
01 02 03 04 05 06 07 08 09 10 | #!/bin/bashmpg=`pidof mpg123`if [ "x${mpg}" == "x" ];then mpg123 /root/SoundHelix-Song-14.mp3 &else killall -9 mpg123fiecho "Ding Dong" |
1 2 | sudo vi /root/bin/ding_dong.shsudo chmod +x /root/bin/ding_dong.sh |
As the last step I wanted to have this script run all the time and to make sure it is started at startup of the PI :
01 02 03 04 05 06 07 08 09 10 | [Unit]Description=Push Button Service[Service]ExecStart=/root/bin/push_button.pyStandardOutput=null[Install]WantedBy=multi-user.targetAlias=ipush_button.service |
1 2 | sudo vi /lib/systemd/system/push_button.servicesudo systemctl enable push_button |
The Raspberry PI button is now all set to act as the Doorbell button for my Video-Doorbell project.