Purpose

This is a sensor monitor that I built for my wife to read the LED lights from my (very basic) washing machine and report the status back to my home-automation controller. Depending on what LED lights are on influences what the text display output on the LCD will display. Status is sent to the home controller using text via V_VAR1 and S_CUSTOM, and custom alerts can be set up from there.

Concept and Implementation

The node/sensor itself is very basic in design and using 5 photo-resistors to read the status of the LED lights. In order to do this, I wanted to isolate the light from the LED’s so that the light spread from them (or any other lights in the room) would not influence the status of the monitor. To do this, I encased the photo-resistors in plastic straws that I then covered in black electrical tape. I then used two popsicle sticks and hot-glue to mount the photo-resistor assemblies in place. For the casing around it, I used white artist/modeling clay.

A realization...

Not thinking things all the way through, I realized that if I were to cover the LED lights on the washing machine itself, I would lose the physical status that the LED’s gave me. In order to get around this I decided to use a 16x2 LCD wired via i2c to show the status from now on.

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The Code

The NODE itself is setup to report values every 15 seconds back to the gateway. It will read the status of the LED lights on the photo-resistors and depending on the combination of what ones are on/off, translates that back to a text based status on the LCD and to the home controller.