adrianhesketh.com

Real terminal bell

I decided that I didn’t like the sound of the terminal bell on my computer. Wouldn’t it be nicer if it was an actual bell?

So, I got a Raspberry Pi, a servo motor and some lego and built a real terminal one.

I didn’t want to spend long on it, so I used some example Python code from https://tutorials-raspberrypi.com/raspberry-pi-servo-motor-control/ and added a Web server so that I could trigger the bell remotely.

from flask import Flask
import RPi.GPIO as GPIO
import time

# Create Flask app.
app = Flask(__name__)

# Start GPIO up.
servoPIN = 17
GPIO.setmode(GPIO.BCM)
GPIO.setup(servoPIN, GPIO.OUT)
p = GPIO.PWM(servoPIN, 50) # GPIO 17 for PWM with 50Hz
p.start(2.5) # Initialization

@app.route("/ding")
def hello():
    p.ChangeDutyCycle(7.5)
    time.sleep(0.3)
    p.ChangeDutyCycle(6.5)
    time.sleep(0.6)
    return "dong"


if __name__ == '__main__':
    try:
        app.run(host = '0.0.0.0',port=5005)
    except KeyboardInterrupt:
        p.stop()
        GPIO.cleanup()

With that in place, I could get the bell to ring using curl.

curl 192.168.0.52:5005/ding

My son and I then set to work building a lego case.

I use https://github.com/tmux/tmux to manage my terminal, so it was a simple case of using the built-in hook feature (https://devel.tech/tips/n/tMuXz2lj/the-power-of-tmux-hooks/) to run the command when the bell rings, and to disable the bell sound on my mac:

set-hook -g alert-bell 'run-shell "curl 192.168.0.52:5005/ding"'

Ah… much nicer.

You can see a video and hear it in action at https://youtu.be/luuI4S4y9-I