Watt Eye has a simple purpose - monitor pulses that comes from the home electric meter, measure the interval between the pulses and compute the real-time energy being consumed, broadcast that onto the network using UDP packets so that CouchCalendar has something to do and display, and publish the data to a web server, where it can be used (graphed or placed into a db).

Dependencies:   IniManager mbed HTTPClient SWUpdate StatisticQueue mbed-rtos NTPClient Watchdog SW_HTTPServer EthernetInterface TimeInterface


  • Reads the time between pulses (which the home electric meter emits as IR for each Watt consumed).
  • Once every 5 seconds, it broadcasts this via UDP to the network, so other nodes can listen to this real-time data.
  • Once every 5 minutes, it posts statistics to a web server for logging.
  • Once a day, it checks the web server to see if there is a SW update (and if so it downloads, installs, and activates it).
  • It syncs to a configured NTP server, but doesn't actually use this information for anything.
  • It hosts a web server, but this is not being used at this time.

So, this is a rather expensive piece of hardware to monitor a single pulse, and yet it is easy to imagine enhancing this:

  • Read the water meter in a similar manner.
  • Read the gas meter in a similar manner.

And even then, there will be many left-over port pins for other uses.