Project announcement: emonLight

Hi all,

I'd like to to share with you this project for a simple home energy meter reading pulse output with a RaspberryPi.


  • Power usage levels are read from an standard energy meter with pulse output;
  • Power usage is collected and sent to;
  • Able to drive a buzzer for signaling high-level usage with configurable soft and hard thresholds;
    • soft threshold: 1 to 3 intermittent beeps signal depending on proximity to time limit; default for soft limit is set to 3300Wh with a time limit of 3 hours;
    • hard threshold: 4 to 6 intermittent beeps signal depending on proximity to time limit; default for hard limit is set to 4000Wh with a time limit of 4 minutes;

You can find source code and detailed information here

​Please feel free to contact me for any comment you may have.

Thank you,

Sergio Moretti

goodfidelity's picture

Re: Project announcement: emonLight

Hello Sergio!

This is a nice idea for a simple energy monitoring device.

If you like to make the alarm feature more usable i suggest thinking about adding a energy / temperature feature so that different alarmlevels can be set depending on outdoor temperature.


This way alarm levels can be set in a way that will not interfere with electrical heating or cooling system.

Description of this diagram is on this URL:


I have not yet found how to create this diagram in the emoncms but sure hopes it will come soon as it is a very useful tool for energy managment of buildings.


sermore's picture

Re: Project announcement: emonLight


I've taken a look at the diagram and it seems to me that this it's a pretty different type of alarm from that currently implemented.

In my opinion what you describe could be built running a script at a time interval, maybe every 4 hours.

This script can read the log file that is currently produced by emonLight in order to collect power usage for that time interval.

With that information and the input from a temperature sensor you can trigger an alarm or whatever.

In order to produce the graph, you can add to the script a call to curl for sending calculated values to

Hope this help!


Sergio Moretti


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