Introduction: Trigger a Webcam With a Button and Raspberry Pi

This instructable will show how to trigger a webcam using Raspberry and a push button. A bash script run at startup and it launch a Python script that survey the GPIO port. When the button is pressed, a "fswebcam" command runs.

Step 1: Materials

- Raspberry Pi 2 Model B

- Webcam (Make sure your camera is UVC complain)

- Push Button

- Breadboard

- Cables

Step 2: Wiring

- Connect the push button to the GPIO pins: GPIO15 (pin 12) and GND (pin 6).

- Connect the Webcam to a USB port.

To make sure your camera was recognized, list the devices with:

$cd /dev/

$ls

Your camera should be listed as /video*

Step 3: Creating Your Program in Python

Open a window in Python 3: Menu>Programming>Python 3>File>New Window

Copy the following code and Save As /home/pi/camerascript.py

import subprocess

import RPi.GPIO as GPIO

import time

GPIO.setmode(GPIO.BOARD)

GPIO.setup(12, GPIO.IN, pull_up_down=GPIO.PUD_UP)

i=0

try:

while True:

input_state = GPIO.input(12)

if input_state == 0:

subprocess.call("fswebcam -d /dev/video0 -r 1024x768 -S0 "+str(i)+"pic.jpg",shell=True) print('PIC CAPTURED')

i=i+1

time.sleep(0.2)

except KeyboardInterrupt:

GPIO.cleanup()

Step 4: Bash Script

Open the terminal and run:

$nano bashscript.sh

Add the following lines to /home/pi/bashscript.sh

#!/bin/bash

echo Launching camera

sudo python camerascript.py

Step 5: Make Your Script Executable and Run at Startup

First, give make your bash script executable:

$chmod ugo +x /home/pi/bashcript.sh

Second, type $nano ~/.bashrc ,and add the following lines at the end of the file to make your script run at startup:

#run startup script

echo .bash running

bash bashscript.sh

Third, autologin as pi user:

$sudo nano /etc/inittab

Comment this line: 1:2345:respawn:/sbin/getty --noclear 38400 tty1

Add this line: 1:2345:respawn:/bin/login -f pi tty1 /dev/tty1 2>&1

Finally, reboot your Pi

$sudo reboot

Step 6: Results

Push the button, wait for the trigger and check if a new jpeg file was created in /home/pi/

Have fun.
Thanks for reading.

Comments

author
shiyazt (author)2016-01-11

The above python code shows an error for me the error is

syntaxError excepted an intended block

How to resolve it ?

IMG_20160112_003008.jpgIMG_20160112_003025.jpg