Python: Close a loop on keypress

Question

I am building an motion detection security camera with a raspberry pi https://www.raspberrypi.org/learning/parent-detector/worksheet/.

The code works fine, but I want the device to run my python code at startup and I want it to close the program when I hit a certain key. As of now, the program runs but wont get out of the loop so I can't get to the raspberry pi desktop (my workaround to this is turning the device off, manually removing the camera, turn the device back on, to get an error because camera is not detected which exits the code to the desktop....very inefficient I know!)

Essentially, this code was written to run the program from a pi that is connected to a monitor, keyboard, etc. I want to just plug it in somewhere and have it arm the camera. Then after I return to the house (work, vacation, etc), I want to plug in a keyboard, hit a key to exit the program, shutdown safly and be able to view any security incidents when I connect it to a monitor.

script code:

from gpiozero import MotionSensor
from picamera import PiCamera
from datetime import datetime

camera = PiCamera()
pir = MotionSensor(4)
while True:
    pir.wait_for_motion()
    filename = datetime.now().strftime("%Y-%m-%d_%H.%M.%S.h264")
    camera.start_recording(filename)
    pir.wait_for_no_motion()
    camera.stop_recording()

you tried this: https://stackoverflow.com/questions/13180941/how-to-kill-a-while-loop-with-a-keystroke — syntaxError, Jun 07 '17 at 20:46
also, all I see at startup (when the code is running) is a black screen. cmd-C does not cause a keyboardinterupt or at least not exit to desktop. — n00b_pyth0n, Jun 07 '17 at 20:50

score 0 · Answer 1 · answered Jun 07 '17 at 20:46

You can stop program execution with Ctrl + C in the command line window that the script is running in.

If you'd like to still do some processing, then wrap your while loop in an try block as such:

try:
    while True:
        pir.wait_for_motion()
        filename = datetime.now().strftime("%Y-%m-%d_%H.%M.%S.h264")
        camera.start_recording(filename)
        pir.wait_for_no_motion()
        camera.stop_recording()
except KeyboardInterrupt:
    pass

# Continue your code here

If you'd like to pick the key that stops the program (other than Ctrl + C) and/or have it stop when you press your key from anywhere in the OS, then I'd recommend using the Keyboard library.

This worked! thank you. Unfortunately the Raspberry pi is just not loading the script correctly because I just get a black screen. I'll keep at it. — n00b_pyth0n, Jun 14 '17 at 16:20

Python: Close a loop on keypress

1 Answers1