Various Updates

December, 2010

I’ve made several minor updates to Watchdog functionality since my last blog post:

  • Internet Connection Status – I’ve been vexed by intermittent internet connection issues with my cable provider.  I thought it would be good to have Watchdog automatically monitor the ability to communicate out to the network.  I added a feature to NetChecker to attempt to ping an external IP address once an hour.  That, alone, proved unreliable, so as a fallback, I also had it attempt to make an HTTP connection with some well known web sites (like  If I could connect, that means the link is up.  If all attempts to ping and connect fail, then Watchdog assumes the connection has dropped and makes a log entry in the main event log.  It also makes a log entry when the connection is restored so I can have an understanding of the duration of the outage (+/- one hour).
  • National Weather Service Warning – I occasionally get severe weather in my area and it’s good to know in advance when it’s coming.  I bought a weather radio to loudly broadcast alerts, but it freaks everyone out when it goes off.  So, I added a feature into NetChecker to monitor the National Weather Service RSS feed for our county and surrounding counties for severe weather hourly.  In the event a severe weather warning is issues, Watchdog broadcasts to the house “The weather is not looking too good right now.  You may want to head down to the basement.”  This has awaken me a few times in the middle of the night, and I was glad for the gentle warning.
  • Doorbell and Telephone sensor:  I purchased and installed the “ELK Doorbell & Telephone Ring Detector ELK-930”.  These modules are inexpensive, easy to install, and work well.  I wired them into Digital IO ports for Watchdog to monitor.  When the doorbell rings or telephone rings, they close the relay and Watchdog knows what’s happening.  Unfortunately, doorbell rings are very fast, so I had to double the monitoring rate of Watchdog to twice per second to make sure I’m not missing the momentary press of the doorbell.
  • House Occupation Status – In order to automate some functions, it became necessary to determine if the house was currently occupied or unoccupied.  I accomplished this by watching for a car to depart.  Once a car departs, the house waits for 5 minutes and monitors the motion sensors throughout the house.  If no motion is detected, it goes into an Unoppupied state and takes the following actions:  Turns off all the X10 lights and adjust the thermostat 2 degrees (up or down depends on the season).  If motion is detected or a door is opened before the car returns, the house automatically moves back to an occupied state and returns the thermostat to its original setting.  If the car returns to an unoccupied house, Watchdog automatically turns on X10 lights (after dark), returns the thermostat to the original setting, and greets us upon entry:  “Welcome home, while you were gone, you missed 3 phone calls, 2 visitors and the mail was delivered”.  Or, “Welcome home, while you were gone nothing interesting happened.”


ELK-930  The ELK-930 module


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