Idea and reason
One of my long running projects, “lights off” comes from the need to know : “Did I turned off my bathroom light?” ; “This light are on for too much time, I wonder how much I am paying for it”.
Without wanting to rewire my house, I came up with designing the WiFi switches, battery powered.
To do so, the wall switch is controlling the Mega’s inputs that is setting and resetting the relay.
For the relay I am using a latch relay as it does not consume power during a set state.
After the state is set/reset, using the WiFi transceiver NRF24l01+ information is sent to the base station.
The switch is designed to be able to be turned off remotely and therefore the watchdog is waking the device to listen for an off command.
This approach comes from the need of the project and also it is a major improvement on the battery life. The current configuration allows running on 2 AAA batteries for 2 months.
For the base station I chose the RasPi as it can act also as a server if needed to hold the DB and the webapp.
Hooked with a NRF24l01, a daemon is listening for events from the switches and inserting them in the DB ( MongoDB).
Also the daemon is responsible in sending off command to a certain switch.
Created with Meteor, the dashboard of the web interface displays the current state of all configured switches.
The “on” switches can be turned off remotely from the app.
— add power consumption calculation based on the historical data
— create a mesh of switches with NRF24Network ( current limitation is at 6 switches)
— attempt to decrease the power consumption.
Schematics — switch unit
Currently I have made 2 versions ( 5V and 3.3V) both plugable in the wall as seen from the pictures.
The 3.3 V is attached to this project
The pictures below show the finished prototypes.
For more detail: Lights off ! WiFi home lights monitoring and control