watz

• Status: ✅ Active
• Contributors: @scottsweb
• Description: A WiFi smart meter / pulse counter built upon a Spark / Particle Core.
• Author: Scott Evans
• Author URI: http://scott.ee
• License: GNU General Public License v2.0
• License URI: http://www.gnu.org/licenses/gpl-2.0.html

About

watz is a WiFi smart meter / pulse counter. It mounts to the LED on your electricity meter and measures the number of pulses in a given time period. This is used to generate real time power information. This data is periodically pushed to the Particle cloud and can be subscribed to via server-sent events.

The events are:

• watz - pushed every 10 minutes, contains a kW reading and a pulse count
• watzup - pushed every time 1000 pulses are detected to allow tracking of the meter total
• watzbatt - pushed every 10 minutes and uses the official power shield to grab batter information

To log the data I am using the hosted emoncms service. I relay the data via Node-RED on a Raspberry Pi using the Particle and emoncms nodes:

When the kW data arrives with emoncms you will need to multiply it by 1000 to get the current watts value. After a bit of tweaking your electricity dashboard should looks something like this:

Issues/Problems/Questions? Open a GitHub issue. You can also contact me via scott.ee or twitter (@scottsweb).

Hardware

• Particle Photon
• Particle Power Shield
• TSL251R-LF 3.3v Photodiode
• A power source (I went for battery + solar as my meter is outside the house)

Circuit

The included watz.fzz file can be opened in Fritzing. Replace the transistor with the TSL251R-LF. Version 2.0 of the code the board requires the Photon and the TSL251R-LF to be attached to the WKP pin to bring the board out of deep sleep.

Installation

Copy the contents of watz.ino into the Particle Build IDE and flash your Photon.

Further Reading

• http://openenergymonitor.org/emon/buildingblocks/introduction-to-pulse-counting
• http://www.reuk.co.uk/Flashing-LED-on-Electricity-Meter.ht
• http://jeelabs.net/projects/cafe/wiki/Electricity_consumption_meter
• http://www.airsensor.co.uk/component/zoo/item/energy-monitor-mk2.html

Changelog

2.0

• Upgraded to Photon board
• Added support for Power Shield
• Battery life monitoring
• Deep sleeping to improve battery performance
• SEMI_AUTOMATTIC to have better control over cloud connection

1.0

• Initial release