Raspberry Pi: Amazing Projects from Scratch

Logging detection data

With any system, it's useful to be able to log data when something happens. We can do this with our detectors too by writing to a log file every time a detector in a zone is triggered. This way, you can keep a log of every time someone enters a room, which you can review at a later date even if the system isn't armed. You can also keep a log of when the system is armed and disarmed.

Here's a simple script that shows you how to do this whenever an event happens on our zones connected to the GPIO inputs:

#!/bin/bash #set up the I2C expansion port sudo i2cset –y 1 0x20 0x00 0xFF #reset status CURR_STATE="0x00" LAST_STATE="0x00" #path to the log file LOG_FILE="/etc/pi-alarm/zones.log" # loop forever while true do # read the gpio ...